LINAC2018 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOPO016	Narrow-Band Terahertz Generation from Beam Pipe with Helix Wires	electron, radiation, wakefield, impedance	65
	D. Wang TUB, Beijing, People’s Republic of China
	We studied through analysis and numerical simulations the use of a relativistic electron bunch to drive a metallic beam pipe with helix wire inside, for the purpose of gen-erating narrow-band terahertz radiation. we have shown that the frequency is related to the radius of the pipe and that of the wire, thus one can generate a narrow-band radiation pulse with frequency tunable through this scheme with different pipes and wires. The total energy of a few milli-Joules. The pulse length tends to be on the order of hundreds of picoseconds. We have also shown that, if the pipe radius is tapered along its length, the generated pulse will end up with a frequency chirp. wangdan2016@mail.tsinghua.edu.cn yanlx@mail.tsinghua.edu.cn
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO016
About •	paper received ※ 12 September 2018 paper accepted ※ 15 January 2019 issue date ※ 18 January 2019
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MOPO018	Development of an Improved Capture Section for the S-DALINAC Injector*	cavity, electron, linac, gun	68
	S. Weih, M. Arnold, J. Enders, N. Pietralla TU Darmstadt, Darmstadt, Germany D.B. Bazyl, H. De Gersem, W.F.O. Müller TEMF, TU Darmstadt, Darmstadt, Germany
	For the injector of the superconducting Darmstadt electron linear accelerator S-DALINAC, the design of a new capture cavity was recently completed. This beta-reduced structure will optimize the capture of low-energy electron bunches from the gun section and therefore improve the longitudinal beam quality of the injector beam, as simulations have shown. The existing cryomodule of the injector has to be modified for the installation of the new cavity. These modifications include adaptions of the tuner frame as well as modifications of other surrounding parts. To improve the diagnostics in the low-energy section, an energy-spread measurement setup is currently also under development. In this contribution the cryomodule modifications as well as simulation results for the longitudinal beam dynamics are presented. *Work supported by DFG through GRK 2128 "AccelencE"
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO018
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO020	Beam Dynamics Studies and Instrumentation Tests for Bunch Length Measurements at CLEAR	experiment, gun, electron, radiation	74
	L. Garolfi, M. Bergamaschi, R. Corsini, A. Curcio, S. Döbert, W. Farabolini, D. Gamba, I. Gorgisyan CERN, Geneva, Switzerland C. Bruni, P. Lepercq, H. Purwar, C. Vallerand LAL, Orsay, France W. Farabolini CEA/DSM/IRFU, France
	A new CERN Linear Electron Accelerator for Research (named CLEAR) has been installed as a general-purpose user facility to study novel accelerating techniques, high-gradient structures, instrumentation and irradiation experiments. CLEAR is a flexible accelerator that can provide high quality bunched electron beams with a wide range of beam parameters up to an energy of 220 MeV, offering several testing capabilities. Among all the potential applications, novel accelerating techniques, such as plasma acceleration and THz generation are considered. These applications require shorter bunches, down to the 100 fs level. This paper reports on beam dynamics studies and instrumentation tests to establish a bunch length of this order in CLEAR. The short bunches are generated using adiabatic bunching in the first accelerating structure. For bunch length diagnostic CLEAR is equipped with a streak camera and a transverse deflecting cavity. Alternatively a phase-scan of the last accelerating structure could be used as well to estimate the bunch length. The experimental results with respect to these different techniques are presented and compared with simulations.
	Slides MOPO020 [0.864 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO020
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO066	Simulation of the Transitional Process in Accelerating Sections by Equivalent Circuit Method	coupling, operation, MMI, interface	145
	S.V. Matsievskiy, V.I. Kaminskiy, Ya.V. Shashkov MEPhI, Moscow, Russia
	Nowadays linac accelerating RF systems design is usually done by the finite difference method. It provides high accuracy of calculations and freedom in topology choosing, but may draw considerable amounts of computer resources with long calculation times. Alternative to this method, equivalent circuit method exists. The basic idea of this method is to build a lumped element circuit, which with certain approximation acts as an original accelerating cell. It drastically reduces the number of equations to solve. This method is long known but usually only used for the particular accelerating structures when speed of calculation is a key-factor. Present paper describes a way to numerically simulate transition processes in arbitrary coupled accelerating cells using the equivalent circuit method. This approach allows simulating transitional processes in accelerating structures significantly faster and allows doing so for structures with high quality factor and many cells - a hard task for conventional transient solvers based on the finite difference method.
	Poster MOPO066 [0.519 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO066
About •	paper received ※ 23 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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MOPO070	Construction of the Side-coupled Standing-wave e-Linac	cavity, linac, coupling, electron	151
	S. Zarei Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran F. Abbasi Shahid Beheshti University, Tehran, Iran M. Bahrami, M. Lamehi IPM, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran
	Due to Iran’s growing need for accelerators in various applications, NSTRI electron linear accelerator project has been defined for medical and inspection applications. This accelerator is a 6 MeV side-coupled standing-wave that operate is π /2 mode in the frequency of 2998.5 MHz. In this paper the construction and measurement results of the tube of this accelerator are presented. The prototype tube was constructed from aluminum and was clamped with bolts. By using a network analyzer, electric and magnetic probes and a side-coupled cavity tuning method and a bead-pull measurement technique, RF measurements were carried out. The resonant frequency and quality factor have been achieved 2998.5 MHz and 7940 respectively . low-energy accelerator, construction of linac, standing-wave linac
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO070
About •	paper received ※ 12 September 2018 paper accepted ※ 09 November 2018 issue date ※ 18 January 2019
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MOPO077	Design of the High Gradient Negative Harmonic Structure for Compact Ion Therapy Linac	linac, proton, coupling, operation	160
	S.V. Kutsaev, R.B. Agustsson, A.Yu. Smirnov, A. Verma RadiaBeam, Santa Monica, California, USA A. Barcikowski, R.L. Fischer, B. Mustapha ANL, Argonne, Illinois, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE-SC0015717 and Accelerator Stewardship Grant, Proposal No. 0000219678 A novel concept for an Advanced Compact Carbon Ion Linac (ACCIL) that will deliver up to 1 pnA of carbon ions with variable energy from 45 MeV/u to 450 MeV/u in a 45 m footprint, has been developed by Argonne National Laboratory (ANL) in collaboration with RadiaBeam. The ACCIL will have a 35 MV/m real-estate accelerating gradients that became possible to achieve with the development of novel S-band high-gradient structures, capable of providing 50 MV/m accelerating gradients for particles with β>0.3. In particular, a β=0.3 structure based on the novel approach of operation at the first negative spatial harmonic with the increased distance between the accelerating gaps will be presented. This is the first attempt to reach such high gradients at such small velocities. RadiaBeam and ANL have demonstrated the feasibility of building this structure for accelerating carbon ions by means of advanced computer simulations and are currently working towards the fabrication of this structure for high power tests.
	Slides MOPO077 [1.863 MB]
	Poster MOPO077 [0.923 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO077
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO087	Cold Test of Hybrid RFQ Prototype	rfq, quadrupole, cavity, linac	184
	P.Y. Yu, Y. He, C.X. Li, F.F. Wang, Z.J. Wang, B. Zhang IMP/CAS, Lanzhou, People’s Republic of China
	Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator, which is combined by four-vane RFQ structure and CH-DTL structure. It has higher energy gain rate compared to conventional RFQ, and it is more compact than traditional DTL. In order to research on process exploration and RF parameters of this structure, an aluminium prototype is developed. The cold test of Hybrid RFQ prototype is completed. This paper will present the results and analysis of the test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO087
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO090	Measurements of the First Room Temperature CH Cavity for MYRRHA at IAP Frankfurt	cavity, resonance, status, rfq	193
	K. Kümpel, S. Lamprecht, P. Müller, N.F. Petry, H. Podlech, S. Zimmermann IAP, Frankfurt am Main, Germany
	Funding: This work has been supported by MYRTE which is funded by the European Commission under Project-ID 662186. The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project is a planned accelerator driven system (ADS) for the transmutation of long-living radioactive waste. A critical passage for the beam quality and especially for the emittance is the injector, which for the MYRRHA project consists of a 4-Rod RFQ, two Quarter Wave Rebunchers (QWR) and a total of 16 normal conducting CH-DTL cavities. The first installment of the MYRRHA injector in Louvein-La-Neuve (Belgium) will include an ion source, a RFQ, the QWRs and the first seven CH DTL cavities. This paper will report on the status of the low level tests on CHs 1 and 2 as well as on further developments on CHs 8-15.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO090
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO093	A Study of a Cooling Configuration for an OFHC Copper Rebuncher	cavity, linac, pick-up, vacuum	200
	O. Mazor, M. Bukai, D. Nusbaum, J. Rodnizki Soreq NRC, Yavne, Israel E. Dyunin Ariel University, Ariel, Israel G. Ziskind Ben-Gurion University in the Negev, Beer Sheva, Israel
	Funding: Pazy Fund (Israel Atomic Energy commission) https://pazy.org.il A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction for the MEBT of SARAF Phase II proton/ deuteron linac. The rebuncher is designed to bunch a 5 mA CW beam at 176 MHz. The required cavity voltage according to beam dynamics evaluation is 150 kV with a beam aperture diameter of 40 mm at a beam energy of 1.3 MeV/u with a Q value of 8000. Considering utilizing this cavity for enhancing the beam energy, the cooling configuration is explored for a cavity voltage of 300 kV, consuming 20 kW dissipated power, at a peak electric field of 16 MV/m, equivalent to the Kilpatrick limit. The electro magnetic study conducted with the CST RF simulation package was reproduced at ANSYS HFSS. The simulated dissipated power along the rebuncher for 20 kW forward power injected through the coupler port with the HFSS driven model were assigned to the ANSYS Fluent model to explore the resulted temperature map. Several evolved cooling configurations were studied, including cooling of the drift tubes. In this configuration the temperature rise along the cavity is in the range of 30 K. A detailed design of the four gap rebuncher is following this study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO093
About •	paper received ※ 03 September 2018 paper accepted ※ 22 September 2018 issue date ※ 18 January 2019
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MOPO096	Realistic Modeling of MEBT for the New LANSCE RFQ Injector	DTL, emittance, quadrupole, rfq	211
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	The new RFQ-based proton injector at LANSCE requires a specialized medium-energy beam transfer (MEBT) after the RFQ at 750 keV due to a following long (~3 m) existing common transfer line that also transports H⁻ beams to the DTL entrance. The horizontal space for MEBT elements is limited because two beam lines merge at 18-degree angle. The MEBT includes two compact quarter-wave RF bunchers and four short quadrupoles with steerers, all within the length of about 1 m. The beam size in the MEBT is large, comparable to the beam-pipe aperture, hence non-linear 3D fields at large radii and field-overlap effects become important. With CST Studio codes, we calculate buncher RF fields and quadrupole and steerer magnetic fields, and use them for particle-in-cell beam dynamics modeling of MEBT with realistic beam distributions from the RFQ. Our results indicate significant emittance growth in MEBT not predicted by the standard beam dynamics codes. Its origin is traced mainly to the quadrupole edge fields; the buncher RF fields also contribute noticeably. Proposed design modifications improve the MEBT performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO096
About •	paper received ※ 10 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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MOPO101	LINAC-multitool - an Open Source Java-toolkit	linac, cavity, GUI, MMI	217
	M. Schwarz, D. Bade, J. Corbet, H. Podlech IAP, Frankfurt am Main, Germany
	Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR Dedicating more precious time to advanced research instead of spending it towards timeconsuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute’s R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO101
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO116	Study on the Control Technology of Large-load Time Constant Accelerator Magnet Power Supply	controls, power-supply, collider, superconducting-magnet	239
	X. Wang, F. Long IHEP, Beijing, People’s Republic of China
	With the increasing application of power supply to industrial system, digital control system has become the mainstream of modern industrial control system. The wide application of digital control system has also led to the rapid development of digital controller. In the field of accelerator magnet power supply, the adoption of digital closed-loop control has become a trend in recent years. Due to the system’s tracking and regulation characteristics, the output current will slowly track the change of the given value in the course of the given current gradually rising. When the system reaches steady state, the disturbance of the system requires the regulator to adjust at a faster rate to correct the impact of the disturbance on the system. Today’s digital power supply control method mainly reflected in when load time constant is large, interference or load change, the power output is prone to overshoot or adjust the time is long, so the tracking and adjustment features cannot be met simultaneously. Therefore, this paper will study the power supply digital control technology for large - load time constant and the independent control method of tracking and regulating.
	Poster MOPO116 [0.307 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO116
About •	paper received ※ 21 August 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019
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MOPO119	Design of a Fully Automated Test Bench for Measuring the Field Distribution in Standing Wave Cavity	cavity, coupling, controls, network	246
	Y. Lu, G. Feng, T. Hu, J. Jiang, X.D. Tu, Y.Q. Xiong HUST, Wuhan, People’s Republic of China
	The resonant cavity plays a great role in the linear accelerator. An accurate measurement of the cavity field distribution is very important to design linear accelerators. A fully computer controlled bench for the electric field distribution has been developed in this context. Based on the perturbation theory, the acquisition of the resonant frequency shift is proportional to the square of E (electric field). In order to verify the reliability of the test bench, a standard cylindrical cavity has been tested in this measurement system. The simulation by HFSS (High Frequency Structure Simulator) and the practice will be both presented in this paper. And the result demonstrates that, because of its high concentricity, the automated test bench achieves high precision in measuring the distribution of electric field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO119
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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MOPO127	Recent Results from MICE on Multiple Coulomb Scattering and Energy Loss	scattering, emittance, detector, radiation	267
	J.Y. Tang IHEP, Beijing, People’s Republic of China J.C. Nugent University of Glasgow, Glasgow, United Kingdom
	Funding: STFC, DOE, NSF, INFN, CHIPP and more Multiple Coulomb scattering and energy loss are well known phenomena experienced by charged particles as they traverse a material. However, from recent measurements by the MuScat collaboration, available simulation codes (GEANT4, for example) are known to overestimate the scattering of muons in low Z materials. This is of particular interest to the Muon Ionization Cooling Experiment (MICE) collaboration which has the goal of measuring the reduction of the emittance of a muon beam induced by energy loss in low Z absorbers. MICE took data without magnetic field suitable for multiple scattering measurements in the fall of 2015 with the absorber vessel filled with xenon and in the spring of 2016 using a lithium hydride absorber. In the fall of 2016 MICE took data with magnetic fields on and measured the energy loss of muons in a lithium hydride absorber. These data are all compared with the Bethe-Bloch formula and with the predictions of various models, including the default GEANT4 model. Submitted by the MICE speakers Bureau. If accepted a member of the collaboration will be selected for the mission
	Poster MOPO127 [0.842 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO127
About •	paper received ※ 19 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019
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MOPO132	The 7 MeV APF DTL for Proton Therapy	DTL, proton, rfq, injection	277
	X.C. Xie, D.M. Li, X. Li, Y.H. Pu, J. Qiao, M.H. Zhao, Z.T. Zhao SINAP, Shanghai, People’s Republic of China Y.H. Pu, X.C. Xie, F. Yang Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China
	Funding: This work is fund by Ministry of Science and Technology of the People’s Repulic of China, under Grant Number 2016YFC0105408 A 7MeV alternating phase focused (APF) drift tube linear (DTL) for proton therapy has been designed, and a design code has been developed based on a sinusoidal synchronous phase formula and a linearly increasing electrode voltage assumption. The design procedure includes the radio frequency quadrupole (RFQ) to drift tube linac (DTL) matching, and end-to-end simulation that conducted by Trace Win. Moreover, a cutting method has been performed to correct the integral electric field deviation of RF gaps.
	Slides MOPO132 [4.219 MB]
	Poster MOPO132 [2.604 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO132
About •	paper received ※ 20 August 2018 paper accepted ※ 15 January 2019 issue date ※ 18 January 2019
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TUPO004	RF Design and Cold Model Measurement of an IH-DTL for HIMM Injector	DTL, cavity, linac, quadrupole	329
	H. Du, Q.Y. Kong, Z.S. Li, K.D. Wang, X. Yin IMP/CAS, Lanzhou, People’s Republic of China
	An interdigital H-mode drift tube linac (IH-DTL) will be constructed as a postinjector linac for the Heavy Ion Medical Machine (HIMM). Its resonant frequency, injec-tion and final energies are determined from beam dynamics and hardware parameters considerations of the entire machine to be 162.5MHz, 600keV/u and 4MeV/u, respectively. The beam duty cycle of the injector linac is less than 0.1% based on the injection requirements of the synchrotron. Beam dynamics and RF structure design and optimize of the IH-DTL has been finished. The maximum surface electric field is less than 2.0-times the Kilpatric limit for accelerating C⁴⁺ beam. This IH-DTL contains 42 accelerating gaps and two focusing quadrupole triplets. In order to examine the field distribution of the IH-DTL which reaches the length of 3.17m, an aluminum alloy 1:1 cold model cavity with 4 moveable tuners and 2 empty focusing magnet shell was constructed. The relative intertube-distance errors are less than ±50μm. The measurements show that the gap voltage values can match the CST-MWS simulating results within relative difference of ±3% by adjusting the 4 moveable tuners.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO004
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO010	Muon Acceleration Test with the RFQ Towards the Development of the Muon Linac	experiment, acceleration, rfq, diagnostics	342
	R. Kitamura University of Tokyo, Tokyo, Japan S. Bae, S. Choi, B. Kim SNU, Seoul, Republic of Korea Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, T. Yamazaki KEK, Tsukuba, Japan K. Hasegawa, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Iijima, Y. Sue Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan H. Iinuma, Y. Nakazawa Ibaraki University, Hitachi, Ibaraki, Japan K. Ishida RIKEN Nishina Center, Wako, Japan S. Li The University of Tokyo, Graduate School of Science, Tokyo, Japan M. Otani, N. Saito J-PARC, KEK & JAEA, Ibaraki-ken, Japan G.P. Razuvaev Budker INP & NSU, Novosibirsk, Russia
	The muon linac to accelerate muons 212 MeV is planned in order to measure the muon dipole moments precisely in the J-PARC. The muon acceleration with a RF accelerator hasn’t been demonstrated yet in the world. Therefore the muon acceleration test with the RFQ as the feasibility test of the muon linac was demonstrated at the Muon D line in the J-PARC MLF. Conventional muons are cooled with producing ultra-slow muons using the muonium production and the ionization laser for the muon linac. However these apparatuses couldn’t be used because of the limitation of the experimental area in the acceleration test. Therefore the conventional muon was converted to the negative muonium ion (Mu-) with less than 2 keV using the thin aluminum foil target as the easy cooling method. The Mu- was finally accelerated to 90 keV using the RFQ. The accelerated Mu- was selected with a diagnostic beam line and identified with the Time-Of-Flight measurement using a MCP detector. The result of the world’s first muon acceleration test with the RFQ will be reported in this presentation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO010
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO016	High Frequency RFQ Design and LEBT Matching for the CERN TwinEBIS Ion Source	rfq, emittance, gun, space-charge	358
	V. Bencini, J.-B. Lallement, A.M. Lombardi, H. Pahl, J. Pitters, F.J.C. Wenander CERN, Geneva, Switzerland M. Breitenfeldt AVO-ADAM, Meyrin, Switzerland A.I. Pikin BNL, Upton, Long Island, New York, USA
	An Electron Beam Ion Source (EBIS) is being developed at CERN for production of highly charged ions, for instance fully stripped 12C. The focus has so far been on the electron gun design, aiming for a high current compression, which results in a rapid ionisation process and thereby high repetition rate. Initial commissioning tests of such an electron gun, the so-called MEDeGUN, have already been performed and we are now in the process of designing a multi-purpose ion extraction and diagnostics line. The Low Energy Beam Transport (LEBT) line will transport the ions into the downstream Radio Frequency Quadrupole (RFQ) with a nominal energy of 15 keV/u. The 750 MHz RFQ is designed to accelerate ions from 15 keV/u up to the final energy of 2.5 MeV/u. After the RFQ design was finalized and its acceptance calculated, the beam matching to the RFQ was studied, finding a set of parameters for the LEBT that maximize the transmission through the RFQ. Details of the RFQ design, of the LEBT matching procedure and its final results are illustrated in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO016
About •	paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO023	Preserving Micron Tolerances Through the Assembly Process of an X-band Accelerating Structure	cavity, HOM, linac, software	377
	J. Sauza-Bedolla, N. Catalán Lasheras, A. Grudiev, S. Lebet, E. Rodriguez-Castro, P. Sobrino-Mompean, A. Solodko, K. T. Szypula CERN, Geneva, Switzerland H. Bursali IZTECH, Izmir, Turkey
	The CLIC structures are designed for operating at X-Band, 2π/3 traveling wave mode with a loaded 100 MV/m gradient. Mechanical tolerances, at the submicron level, are required to satisfy the RF design constraints and beam dynamics and are reachable using ultra-precision diamond machining. However, inherent to the manufacturing process, there is a deviation from the nominal specifications and as a result; incorrect cavity dimensions produce a less efficient linac. Moreover, the assembly process increase the difference from the original geometry. As part of a cost and manufacturability optimization of the structures for mass production, this study aims to identify a correlation between frequency deviations and geometrical errors of the individual discs of the accelerating structures caused by the production process. A sensitivity analysis has been carried out to determine the most critical parameters. Cell frequency deviations have been monitored by bead pull measurements before and after bonding. Several accelerating structure prototypes have been tested to determine our assumptions and to assess if the assembly process preserves the tight tolerances achieved by machining.
	Poster TUPO023 [1.443 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO023
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO039	Tests of the Balloon Single Spoke Resonator	cavity, multipactoring, linac, TRIUMF	417
	Z.Y. Yao, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, H. Liu, Y. Ma, B. Matheson, B.S. Waraich, Q. Zheng, V. Zvyagintsev TRIUMF, Vancouver, Canada
	A balloon variant of the single spoke resonator (SSR) has been designed, fabricated and tested. The cavity is the SSR1 prototype for the Rare Isotope Science Project (RISP) in Korea. It is specifically designed to reduce the likelihood of multipacting barriers near the operating point. A systematic multipacting study leads to a novel geometry, a spherical cavity with re-entrant irises and a spoke. Other than eliminating multipacting around operational gradient, the balloon shape also provides competitive RF parameters and robust mechanical structure. Cryostat cold tests demonstrated cavity performance on each design aspect. The cold tests will be reported in this paper.
	Slides TUPO039 [25.279 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO039
About •	paper received ※ 17 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO051	Design Considerations of a Balloon-shaped SSR Superconducting Cavity	cavity, electron, distributed, superconducting-cavity	448
	H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, S. H. Park, J.Y. Yoon Korea University Sejong Campus, Sejong, Republic of Korea
	A single spoke resonator (SSR, β = 0.51 and f = 325 MHz) is being developed at Korea University. It is well-known that a traditional spoke cavity having flat or round end walls has broad multipacting ranges in acceleration gradient, sometimes including operation region. In general, quite long conditioning time is consumed to overcome such multipacting barriers. In this study, we introduce a balloon-shaped SSR superconducting cavity for the multipacting mitigation due to structural simplicity. The electromagnetic modeling of the SSR was made based on the RF parameter optimization. The simulation results show much narrower multipacting bandwidth, compared to those for the traditional spoke cavity. Mechanical analyses with stiffening structure at maximum allowable working pressures indicate acceptable stresses at the SSR cavity wall. In addition, the resonant frequency shifts due to fabrication and processing for cold tests are predicted and power coupling and tuning mechanism are also investigated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO051
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO052	Design Study of a Prototype 325MHz RF Power Coupler for Superconducting Cavity	pick-up, cavity, superconducting-cavity, resonance	451
	J.Y. Yoon, J.B. Bhang, H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, C.S. Park, S. H. Park Korea University Sejong Campus, Sejong, Republic of Korea E. Kako KEK, Ibaraki, Japan D.Y. Kim, J. Lee Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea I. Shin IBS, Daejeon, Republic of Korea
	Funding: Korea University (Sejong Campus) in South KOREA We present design studies of a prototype RF input power coupler, which provides RF powers to 325MHz cavities up to 18.5 kW in CW mode. The prototype power coupler is a coaxial capacitive type with single ceramic window. In order to optimize the RF coupler design, we performed multi-physics simulations, including electromagnetic, thermal, and mechanical analyses.
	Poster TUPO052 [1.607 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO052
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO083	Beam Dynamics for the FAIR p-Linac Ladder RFQ	rfq, linac, emittance, ion-source	522
	M. Syha, U. Ratzinger, M. Schuett IAP, Frankfurt am Main, Germany
	After the successful measurements with a 0.8 m prototype a 3.3 m Ladder-RFQ is under construction at IAP, Goethe University Frankfurt. It is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the p-Linac at FAIR. Along the acceleration section modulation parameter, aperture and synchronous phase all course (quasi-)linear, which differentiates this design approach from other designs developed at IAP. The ratio of transversal vane curvature radius to mid-cell radial aperture as well as the vane radius itself are constant, which favors a flat voltage distribution along the RFQ. This was verified by implantation of the modulated vane geometry into MWS-CST RF field simulations. The development of adequate beam dynamics was done in close collaboration with the IAP resonator design team. The Los Alamos RFQGen-code was used for the RFQ design and the beam dynamics simulations.
	Poster TUPO083 [0.932 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO083
About •	paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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TUPO085	Modelling of Beam Parameters of RF Linac for GBS-ELI-NP	linac, quadrupole, gun, emittance	528
	P.S. Tracz IFIN-HH, Bucharest - Magurele, Romania
	The Gamma Beam System at the ELI-NP (Extreme Light Infrastructure - Nuclear Physics) currently being constructed in Magurele/Bucharest, Romania will be a high-brilliance advanced source of gamma rays based on laser Compton back-scattering. For a successful operation of the GBS a high brightness low emittance electron beam is of crucial importance. The warm RF linac is designed in two stages - one with the beam up to 300 MeV, and another one about 720 MeV. The S-band photo-injector is combined with a C-band linac. The beam is transported by transfer lines to the interaction points. In this paper we report the results of computer simulations of the electron beam transport in the low energy linac and transfer line up to the low energy interaction point (IP1). The simulation model makes it possible to predict the beam parameters to be recuperated in case of failure of any magnetic or accelerating elements as well as it enables to determine the optimal parameters of replaced components. It will be used for the development of the Gamma Beam System in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO085
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO092	Beam Dynamics and Collimation Following MAGIX at MESA*	target, electron, scattering, radiation	540
	B. Ledroit, K. Aulenbacher IKP, Mainz, Germany
	Funding: * Supported by the DFG through GRK 2128 The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing operation in energy-recovery linac (ERL) mode, where beam energy is recovered by decelerating the beam in linac cryomodules and transferring kinetic energy to the RF. The ERL mode provides the opportunity to operate experiments at peak energy with thin targets, combining high luminosities typical for storage rings and high beam brightness typical for linacs. The MESA Internal Gas Target Experiment (MAGIX) aims to operate jet targets at high luminosities with different gases up to Xenon. As scattering effects in the beam rise with the atomic number, investigations on the impact of the target on beam dynamics and beam losses are required for machine safety. The goal of this work is to understand target induced halo, track halo particles through downstream sections and protect the machine with a suitable collimation system and shielding from direct and indirect damage through beam losses and radiation. The present status of the investigations is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO092
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TUPO093	Excitation of Millimeter Wavelength Cavity Structure	cavity, gun, cathode, emittance	543
	M.V. Arsentyeva NSU, Novosibirsk, Russia A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia
	Excitation of millimeter wavelength cavity structure In this work excitation of W-band structure is studied. The structure consists of cylindrical cavities with the operating frequency of about 96 GHz. We plan to excite the structure by short bunches from the photocathode RF gun. In order to choose structure geometry and beam duration, we performed estimations and simulations; induced voltage was also estimated. Taking into account feasible parameters of the photocathode RF gun such as beam size and emittance, we studied exciting beam transverse dynamics to define its other characteristics (energy and charge). To lead the beam from the whole structure, focusing is needed. After estimation of required magnetic field, we considered possibility of focusing with help of permanent magnets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO093
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO095	Beam Loading with the First Rebuncher of Spiral2, First Measurements	cavity, controls, experiment, linac	546
	M. Lechartier, R. Ferdinand, J.F. Leyge GANIL, Caen, France
	In the SPI2 project the middle energy line (LME) is equiped with a radio frequency qupole and three Rebunchers. The subject of this article is to measure and characterise the effect of the beam loading on the first Rebuncher cavity.
	Poster TUPO095 [1.146 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO095
About •	paper received ※ 20 September 2018 paper accepted ※ 15 January 2019 issue date ※ 18 January 2019
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TUPO109	Electron Cloud Estimates for the Jefferson Lab EIC	electron, sextupole, proton, dipole	563
	K.E. Deitrick, V.S. Morozov, T. Satogata JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In this work, we present preliminary estimates for electron cloud build-up and saturation for the ion ring of the Jefferson Laboratory Electron-Ion Collider (JLEIC) currently under development. Using the baseline ion ring design, we study the impact of various operational parameters on the behavior of the electron cloud for a 100 GeV proton beam, including estimated tune shifts.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO109
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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TUPO113	Beam Dynamics Studies Through Dielectric THz Accelerating Structures	GUI, vacuum, accelerating-gradient, linac	569
	R. Apsimon, G. Burt, A.L. Healy, S.P. Jamison Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R.B. Appleby, E.J.H. Smith UMAN, Manchester, United Kingdom A. Latina CERN, Geneva, Switzerland
	As conventional RF accelerating schemes approach the physical limit of accelerating gradient, the accelerator community is increasingly looking at novel accelerating techniques to overcome these limitations. Moving from the RF to the THz frequency range, higher acceleration gradients of high energy beams can be achieved in compact structures. Beam dynamics studies are crucial as part of the design of novel accelerating structures to maximise the output beam current as well as the accelerating gradient. In this paper we present beam dynamics simulations through dielectric lined waveguide structures using novel techniques to simulate broadband signals for particle tracking studies in RF-Track. The beam parameters through the structure are optimised and we study the dynamics of general broadband accelerating structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO113
About •	paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TUPO120	The Study of the Length and Shape of Beam in a High Power Electron Accelerator	electron, radiation, extraction, industrial-accelerators	584
	M. Salehi, F. Abbasi Davani, B.G. Ghasemi Shahid Beheshti University, Tehran, Iran F. Ghasemi, A.P. Poursaleh NSTRI, Tehran, Iran
	The output beam of a high-power linear accelerator, used for industrial purposes, is irradiated on products and scanning them. In order to improve the dosimetry of radiation which products received and to prevent loss of the attacked- beams to the edge of products, the exact evaluation of scanning length is necessary . One of the other challenges of the scanning beam is the lack of uniformity in dosimetry of received radiation . The scanning beam does not collide in parallel to the products, which is also a challenge to accelerator efficiency. To improve dosimetry of received radiation, the use of trajectory correction magnets is suggested. These magnets correct the beams that do not scan in parallel. Also, using the Monte Carlo code, the dosing rate of received radiation to products is simulated and compared in two non-uniform and uniform modes (corrected by trajectory correction magnets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO120
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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TH1A03	High Brightness Electron Beams from Plasma-based Acceleration	plasma, electron, acceleration, FEL	637
	A. Marocchino, A. Biagioni, E. Brentegani, E. Chiadroni, M. Ferrario, F. Filippi, A. Giribono, R. Pompili, A.R. Rossi INFN/LNF, Frascati (Roma), Italy A. Bacci Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy V. Petrillo Universita’ degli Studi di Milano, Milano, Italy
	Funding: INFN-CNAF and CINECA for high performance computing resources. European Union Horizon 2020 programme N. 53782. Plasma Wakefield acceleration is a promising new acceleration techniques that profit by a charged bunch, e.g. an electron bunch, to break the neutrality of a plasma channel to produce a wake where a trailing bunch is eventually accelerated. The quest to achieve extreme gradient conserving high brightness has prompted to a variety of new approaches and techniques. Most of the proposed schemes are however limited to the only plasma channel, assuming in the vast majority of cases, ideal scenarios (e.g. ideal bi-gaussian bunches and uniform density plasma channels). Realistic start-to-end simulations, from the photo-cathode to FEL via a high gradient, emittance and energy spread preserving plasma section, are mandatory for paving the way towards plasma-based user facilities.
	Slides TH1A03 [25.814 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1A03
About •	paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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TH1A05	Jitter Study for the APS Linac Photo-injector Beam	laser, timing, linac, experiment	647
	D. Hui, M. Borland, J.M. Byrd, Y. Sun ANL, Argonne, Illinois, USA
	Funding: *Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The APS Linac photo-injector can deliver high brightness electron beams to the Linac Extension Area (LEA) for beam experiments such as TESSA (Tapering Enhanced Stimulated Superradiant Amplification). Beam jitter in the device-under-test (DUT) area of the LEA can adversely affect the quality of data for such experiments. In this paper, a start-to-end simulation of jitter is studied. Sources of jitter include photo-cathode drive-laser arrival time, laser energy, and RF phases and voltages of the photo-cathode gun and accelerating cavities. It is found that at the DUT the relative mean energy jitter is the most significant concern, and that improvements in the Linac RF voltage stability can help to reduce it. RMS energy spread are more sensitive to the laser timing and charge jitter. The laser timing jitter itself can be compressed by the magnetic chicane by a factor of 5.6.
	Slides TH1A05 [4.377 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1A05
About •	paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO003	L-band Resonant Ring for Testing RF Windows for ILC	collider, coupling, klystron, linear-collider	679
	B. Du, N. Liu Sokendai - Hayama, Hayama, Japan T. Matsumoto, S. Michizono, T. Miura, F. Qiu KEK, Ibaraki, Japan T. Matsumoto, T. Miura, F. Qiu Sokendai, Ibaraki, Japan
	A resonant ring is widely used for the breakdown test of RF components under high power. It can reach power gain of more than 10dB, which is limited by the attenua-tion of the ring. An L-band resonant ring is constructed for testing RF components of International Linear Collid-er (ILC) which is based on an RF frequency of 1.3GHz. The target of the high power test is 5 MW. We have fin-ished the test of an input power of 500 W using a solid state amplifier, and the principle of the resonant ring is verified. The resonant ring is tuned to an optimal condi-tion, which is preparation for high power operation. This paper details the principle, construction, and test of the L-band resonant ring.
	Poster THPO003 [2.301 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO003
About •	paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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THPO005	High Aspect Ratio Beam Generation with the Phase-space Rotation Technique for Linear Colliders	emittance, gun, collider, linear-collider	685
	M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan P. Piot Northern Illinois University, DeKalb, Illinois, USA J.G. Power ANL, Argonne, Illinois, USA K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio RISE, Tokyo, Japan H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	Funding: This work is partly supported by Grant-in-Aid for Scientific Research (B) and US-Japan Science and Technology Cooperation Program in High Energy Physics. Linear colliders is the only way to realize e⁺ e⁻ collision at higher energy beyond the limit of ring colliders by the huge synchrotron radiation energy loss. In the linear collider, the beam current should be much smaller comparing to the ring collider to save the required electricity. A way to realize an enough luminosity with the small beam current and less energy spread by Beamstrahlung, is collision in flat beam. This high aspect ratio beam can be made by phase-space rotation technique instead of the conventional way with DR (Damping Ring). We present a simulation of this technique and pilot experiments at KEK-STF and ANL WFA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO005
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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THPO007	MESA - Status of the Implementation of the MicroTCA.4-based LLRF Control System	cavity, controls, LLRF, experiment	691
	J.N. Bai, K. Aulenbacher, J. Diefenbach, F. Fichtner IKP, Mainz, Germany P. Echevarria HZB, Berlin, Germany R.G. Heine KPH, Mainz, Germany
	MESA at the Institut für Kernphysik (KPH) at Johannes Gutenberg-Universität Mainz is a multi-turn energy recovery linac (ERL), aiming to serve as user facility for particle physics experiments. The RF-accelerating systems of MESA consist of four 9-cell TESLA superconducting cavities, four normal conducting (NC) pre-accelerator cavities, two NC buncher cavities and two NC chopper cavities. They operate in continuous wave (CW) mode. In order to control the radio frequency (RF) amplitude and phase within the 12 cavities with the required accuracy and stability in the range of better than 0.01% and 0.01°, the MicroTCA.4 based digital low-level RF (LLRF) control system based on the development at DESY, Hamburg will be well adapted for the MESA cavities. In this paper, we describe the theoretical modelling of superconducting cavity and PID controller in SIMULINK which is useful to find the suitable control parameter for the PID controller and to predict the system performance. The progress to date of the implementation and tests of the LLRF system at MESA will also be presented.
	Poster THPO007 [1.274 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO007
About •	paper received ※ 11 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019
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THPO010	Novel Straight Merger for Energy Recovery Linacs	cavity, dipole, experiment, electron	702
	K.E. Deitrick, A. Hutton JLab, Newport News, Virginia, USA A.C. Bartnik, C.M. Gulliford Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA S.A. Overstreet ODU, Norfolk, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. One of the most critical design considerations for an energy recovery linac (ERL) is how to merge the injected bunch onto the linac axis with minimal beam degradation. All merger designs in established and upcoming machines involve significant bending of the injected beam ’ even using a so-called straight merger bends the injected beam several degrees. We propose a merger which reduces the bending of the injected beam by an order of magnitude. By passing both beams through a septum magnet followed by an rf separator cavity with a superimposed dipole magnetic field, the injected beam bends minimally within the cavity, while the recirculated beam bends to align with the linac axis. Here we describe the concept in detail and present simulation results to demonstrate the advantages of such a design, particularly for magnetized beams or minimal energy separation between the injected and recirculated beams. Measurements from an experiment at CBETA evaluating the beam dynamics of the rf separator are presented and compared with simulation results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO010
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO012	Once Recirculating Energy Recovery Linac Operation of S-DALINAC*	linac, operation, acceleration, recirculation	710
	M. Arnold, J. Birkhan, J. Pforr, N. Pietralla, F. Schließmann, M. Steinhorst TU Darmstadt, Darmstadt, Germany F. Hug KPH, Mainz, Germany
	Funding: *Work supported by DFG through GRK 2128 and INST163/383-1/FUGG Since 1991 the superconducting S-DALINAC is running in recirculating operation. It was built in a twice recirculating layout. A third recirculation beam line was added in 2015/2016 as an upgrade. The new recirculation beam line is installed in-between the two existing beam lines. It houses a path length adjustment system capable of changing the length of the orbit for recirculation by up to 10 cm corresponding to the RF wave length at the operation frequency of 3 GHz and consequently to a freedom of RF phase adjustment by 360°. The new beam line can, thus, be utilized for an accelerating operation or, if the change in phase is set to 180°, for an energy recovery linac (ERL) operation. In August 2017 the S-DALINAC was first operated in once recirculating ERL mode and became the first running ERL in Germany. Different aspects of this ERL run have been observed and were evaluated. The layout of the S-DALINAC allows a once or twice recirculating ERL mode. Beam dynamics simulations for both modes have been conducted or are currently under investigation. This contribution will discuss the once recirculating ERL operation, its results, and future plans concerning ERL measurements.
	Poster THPO012 [0.708 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO012
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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THPO026	The Multi-physics Analysis of Dual-beam Drift Tube Linac	DTL, cavity, operation, linac	735
	T. He, L. Lu, W. Ma, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang IMP/CAS, Lanzhou, People’s Republic of China
	The DB-DTL prototype is proposed to validate the fea-sibility of multi-beam accelerator in middle energy region. The main parameters are listed in Table.1. The DB-DTL will operate as pulse injector with the capacity of accelerating proton from 0.56 MeV to 2.5 MeV. The 35.83 kW normalized power dissipation of DB-DTL dis-sipated on the cavity internal surface will heat the cavity and cause cavity temperature rise and structural defor-mation, which will lead to resonant frequency shifting. The cooling water takes away the power to resolve this problem. In this paper, detailed multi-physics field simu-lation of DB-DTL is performed by using ANSYS multi-physics, which is a coupled electromagnetic, thermal and structural analysis.
	Poster THPO026 [0.759 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO026
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO029	Quality Factor and Power Loss of the CSNS DTL	cavity, DTL, operation, linac	741
	P.H. Qu, M.X. Fan, A.H. Li, B. Li, J. Peng, Y. Wang, X.L. Wu CSNS, Guangdong Province, People’s Republic of China Q. Chen, K.Y. Gong, H.C. Liu IHEP, Beijing, People’s Republic of China
	An Alvarez-type Drift tube linac (DTL) was utilized to accelerate the H⁻ ion beam of up to 15mA peak current from 3 to 80MeV of China Spallation neutron source (CSNS). For ease of manufacturing and measurement, the CSNS DTL was divided into four independent cavities. The Q factor of four cavities were given, including the measurement results of low-power[1] and high-power[2], and several reasons for the low Q factor of the cavity in the measurement process were analysed. During the op-eration of the DTL, the frequent alarm of the water flow switch causes the power of the cavity to fall to 0. Esti-mate the power loss of each component, under the cir-cumstances of ensuring adequate water flow, reduce the alarm threshold of the water flow switch of some compo-nents to improve the stability of the system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO029
About •	paper received ※ 22 August 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO035	Tuning and Low Power Test of the 325 MHz IH-DTL at Tsinghua University	DTL, proton, linac, cavity	759
	R. Tang, C.T. Du, X. Guan, Y. Lei, P.F. Ma, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, W.B. Ye, H.Y. Zhang, S.X. Zheng TUB, Beijing, People’s Republic of China J. Li NUCTECH, Beijing, People’s Republic of China
	An interdigital H-mode drift tube linac (IH-DTL), which accelerates proton beam from 3 MeV to 7 MeV has been designed and assembled at Tsinghua University. There are 8 plungers in the 1 m tank and one co-axial coupler is used to feed the power. The frequency is tuned to 325 MHz. The field distribution is measured by the bead perturbation method. Finally, the gap voltage error has been tuned to be smaller than ±3.0%, which satisfies the design requirement. The Q factor of the tank is 7000 while the power dissipation is 244 kW. Details of the low power test is presented.
	Poster THPO035 [1.268 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO035
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO042	An Optimization Method of the Nose-cone Buncher Cavity	cavity, proton, radiation, bunching	778
	W.L. Liu, P.T. Cong, Z.M. Wang NINT, Shannxi, People’s Republic of China H. Jiang, S.X. Zheng TUB, Beijing, People’s Republic of China
	The nose-cone buncher cavity is widely used on proton accelerators. It’s important to properly optimize the cavity geometry for fine RF performance. Howev-er, currently the optimization is usually carried out manually and the criteria are not objective enough. In this paper, an optimization method using the multi-objective, multi-variable optimization approach is presented. The geometry and RF parameters are con-sidered as the variables and objectives respectively. The goal function is defined as the weighted sum of multiple RF parameters. The multi-variable functions are approximately derived from the single-variable functions based on electromagnetic simulation. And an optimization code is developed accordingly which has been applied to the XiPAF debuncher optimization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO042
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO049	Field Tuning of a Radio-frequency Quadrupole Using Full 3D Modeling	rfq, cavity, insertion, linac	798
	T. Morishita, K. Hasegawa, Y. Kondo, H. Oguri JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Otani KEK, Ibaraki, Japan
	The radio-frequency quadrupole linac (RFQ) is operating in the frontend of the J-PARC linac to accelerates 50 mA negative hydrogen beams from 0.05 MeV to 3 MeV. As a backup, the spare RFQ has been fabricated in 2018. The vane-voltage ramping is adopted to improve the acceleration efficiency so that the cross-sectional shape is adjusted longitudinally to produce the designed voltage distribution. Then, the three-dimensional cavity models including modulations and cutbacks were created in CST Micro-Wave Studio. The vane-base widths and cutback depths were optimized to produce the desired vane-voltage distribution. In the final tuning, the heights of the stub turners were also determined based on the tuner responses obtained from the full 3D models. In this paper, the detailed design process of the cavity dimensions and the result of the low-power measurements are described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO049
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO050	Research on the New Cavity Structure of RFQ Accelerator With Bent Vanes at IMP	rfq, cavity, impedance, ECR	802
	L. Yang, T. He, Y. He, C.X. Li, L. Lu, L.P. Sun, C.C. Xing IMP/CAS, Lanzhou, People’s Republic of China L. Yang University of Chinese Academy of Sciences, Beijing, People’s Republic of China
	A new cavity structure of RFQ accelerator with bent vanes is proposed to meet the miniaturization requirement of low frequency heavy ion accelerators at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The new structure has a downsized cross section by bending vanes while keeping a certain vane lengths. It also possesses the advantages of simple cooling structure and high power efficient when used in low frequency. The new structure has obvious advantages in reducing manufacturing difficulty of cavity, cutting down project cost, enhancing facility reliability and stability.
	Slides THPO050 [1.407 MB]
	Poster THPO050 [0.398 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO050
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO051	The Multi-physics Analysis of LEAF RFQ	rfq, cavity, radio-frequency, quadrupole	805
	X.B. Xu, T. He, Y. He, C.X. Li, L. Lu, W. Ma, A. Shi, L.B. Shi, L.P. Sun, C.C. Xing, L. Yang, H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	The 81.25 MHz CW RFQ is designed to accelerate heavy ions with Q/A from 1/7 to 1/2 at 0.5 MeV/u for the Low Energy Accelerator Facility (LEAF) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). The four-vane RFQ consists of six mod-ules with a total length of 5.95 meters, For the CW oper-ating mode, thermal management will be a very important issue, Therefore a multi-physics analysis is necessary to ensure that the cavity can stably operate at the high RF power . The multi-physics analysis process includes RF electromagnetic analysis, thermal analysis, mechanical analysis, and the frequency shift, the cooling water system is used for frequency tunning by the temperature adjustment, and also analyze RFQ undercuts, fixed tuners, and pi-mode rods, the results show that the thermal and structural design of this RFQ is reasonable.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO051
About •	paper received ※ 17 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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THPO057	Redesign of CERN Linac3 RFQ for Lead 29+	rfq, linac, emittance, cavity	818
	S. Benedetti, G. Bellodi, J.-B. Lallement, A.M. Lombardi CERN, Geneva, Switzerland
	CERN Linac3 is at the start of the CERN Heavy Ion Facility, providing 4.2 MeV/u ion beams to the Low Energy Ion Ring (LEIR). It mostly accelerates 208Pb²⁹⁺, though in recent years runs were performed with 40Ar¹¹⁺ and 129Xe²²⁺, in view of the increasing interest of the physics community towards lighter ions experiments. In the framework of the LHC Injectors Upgrade (LIU) project, measurements and beam dynamics simulations showed that a transmission bottleneck of Linac3 is represented by the RFQ. As this accelerator was originally designed for 208Pb²⁵⁺, the lower beam rigidity of the heavy ions currently in use and planned for the future permits a redesign of the RFQ optics aimed at increasing its transverse acceptance, and thus the transmitted beam current. A study of this has been performed, and the methodology adopted and the results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO057
About •	paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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THPO058	RF Design of a High-frequency RFQ Linac for PIXE Analysis	rfq, linac, cavity, proton	822
	H.W. Pommerenke, A. Bilton, A. Grudiev, A.M. Lombardi, S.J. Mathot, E. Montesinos, M.A. Timmins, M. Vretenar CERN, Geneva, Switzerland H.W. Pommerenke, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: This work has been sponsored by the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (grant no. 05E12CHA). Protons with an energy of few MeV are commonly used for Ion Beam Analysis of materials, in particular with the Proton Induced X-ray Emission technique (PIXE). Because of its non-damaging character, PIXE is used in a variety of fields, in particular for the diagnosis of cultural heritage artwork. A compact accelerator based on a high frequency RFQ (Radio Frequency Quadrupole) linac has been designed and is being built at CERN. The length of the RFQ is only one meter and it allows the acceleration of a proton beam up to an energy of 2 MeV. The complete system is conceived to be transportable, allowing PIXE analysis almost anywhere. This paper covers the RF design of the compact RFQ operating at 750 MHz. We present general accelerator parameters and the current state of the RF design, which includes RFQ geometry and coupler design, thermal simulation and first particle tracking results.
	Slides THPO058 [2.404 MB]
	Poster THPO058 [2.192 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO058
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO060	First RF Measurements of the 325 MHz Ladder RFQ	rfq, linac, proton, coupling	826
	M. Schuett, U. Ratzinger, M. Syha IAP, Frankfurt am Main, Germany
	Funding: BMBF 05P15RFRBA Based on the positive results of the unmodulated 325 MHz Ladder-RFQ prototype from 2013 to 2016, we developed and designed a modulated 3.3 m Ladder-RFQ. The unmodulated prototype Ladder-RFQ features a very constant voltage along the axis. The RFQ was high power tested at the GSI test stand. It accepted 3 times the RF power level needed in operation. That level corresponds to a Kilpatrick factor of 3.1 with a pulse length of 200 µs. The 325 MHz RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the proton linac within the FAIR project. This particular high frequency creates difficulties for a 4-ROD type RFQ, which triggered the development of a Ladder RFQ with its higher symmetry. The results of the unmodulated prototype have shown, that the Ladder-RFQ is a suitable candidate for that frequency. For the present design duty cycles are feasible up to 5%. The basic design and tendering of the RFQ has been successfully completed in 2016. Manufacturing will be completed in August 2018. We will show the the finalization of manufacturing as well as first low level RF measurements of the Ladder RFQ. Journal of Physics: Conf. Series 874 (2017) 012048 **Proceedings of LINAC2016, East Lansing, TUPLR053
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO060
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO061	Beam Characterization of the MYRRHA-RFQ	rfq, diagnostics, proton, injection	830
	P.P. Schneider, M. Droba, O. Meusel, H. Podlech, A. Schempp IAP, Frankfurt am Main, Germany D. Noll CERN, Geneva, Switzerland
	Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) #05P15RFRBA and HORIZON 2020 for the MYRRHA project #662186 and HIC for FAIR. The Linear Accelerator for the MYRRHA project* is under construction. In a first step the linac up to 100 MeV will be realized. The LEBT section has been set into operation in Belgium and the RFQ is installed in summer 2018. A system to analyze the ion beam consisting of a slit-grid emittance scanner, a beam dump and a momentum spectrometer, called diagnostic train descripted in *, will be set on the rails to characterize the beam at the RFQ injection point. The results will be used to adjust the optimal matching for the RFQ. After the measurements downstream the LEBT, the diagnostic train begins its journey along the beam line and at the first station the RFQ is installed. The accelerated beam of the RFQ is then analyzed and optimized. In addition to optimization of transmission the artificial production of beam offsets in the LEBT is of special interest. These will be measured at the injection point to estimate the range of possible offsets. In the following measurements these offsets will be used to study the influence of the offsets on the RFQ performance. Furthermore, the RFQ parameters are varied to see their influence on the beam transport, transmission and beam quality. H.Aı̈t Abderrahim et al. "MYRRHA: A multipurpose accelerator driven system for research & development", 2001 ** 1st Experiments at the CW-Operated RFQ for Intense Proton Beams, LINAC16
	Poster THPO061 [4.610 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO061
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO062	IFMIF/EVEDA RFQ Preliminary Beam Characterization	rfq, MMI, operation, proton	834
	E. Fagotti, L. Antoniazzi, L. Bellan, M. Comunian, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo INFN/LNL, Legnaro (PD), Italy T. Akagi, K. Kondo, K. Sakamoto, T. Shinya, M. Sugimoto QST, Aomori, Japan P. Cara IFMIF/EVEDA, Rokkasho, Japan H. Dzitko, I.M. Moya F4E, Germany R. Heidinger, A. Marqueta Fusion for Energy, Garching, Germany I. Podadera CIEMAT, Madrid, Spain
	The IFMIF/EVEDA RFQ is the longest and powerful operated. Therefore, it requires a careful characterization from several aspects: beam dynamics, RF, mechanics, installation and commissioning. Due to the very large power handling, the preliminary beam operation was decided to be performed with a low proton beam current at one half of the voltage needed for deuteron accelera-tion, i.e. from 8 mA to 30 mA at 2.5 MeV in pulsed mode, with respect to the nominal 130-mA deuteron beam at 5 MeV in CW. In this framework, it will be presented the characterization of the RFQ in terms of simulation and measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO062
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO068	AN Effect of Field Emission on Low Beta Superconducting Cavities	pick-up, cavity, SRF, linac	849
	X. Liu, Z. Gao, Y. He, G. Huang IMP/CAS, Lanzhou, People’s Republic of China
	Superconducting RF (SRF) technology is widely ap-plied in particle accelerators to shorten the accelerator length and lower the construction price due to its high acceleration gradients with low rf losses. Field emission is the chief limitation associated with the surface electric field which will finally determine the cavity performance during the operation. The pickup-drop signal caused by field emission seriously affect the stable operation of the superconducting linac in the Chinese initiative Accelera-tor-Driven Sub-critical System (CiADS) demon facility. Simulations of the field emission effect and experimental measurements of the pickup-drop signal have been per-formed on the half wavelength resonator (HWR) cavity. And a modified design of the pickup antenna will be discussed to solve the pickup-drop problem.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO068
About •	paper received ※ 12 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019
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THPO076	Multiphysics Design Studies of a Superconducting Quarter-wave Resonator at Peking University	cavity, multipactoring, SRF, accelerating-gradient	863
	M. Chen, S. Chen, A.Q. Cheng, W. Cheng, J.K. Hao, S.W. Quan, F. Zhu PKU, Beijing, People’s Republic of China
	Funding: This work is supported by National Basic Research Program (2014CB845504) A 81.25MHz, geometric β=0.046 quarter-wave resonator has been designed and analysed at Peking University. This paper mainly presents the multi-physics studies of this cavity, include electromagnetic design, mechanical analysis and multipacting simulation, to predict its behaviour under practical operating process. Various transverse vibration modes of inner conductor were found under different fixed conditions and an asymmetric shorting plate was adopted to avoid high possibility of multipacting "quarter-wave resonator" "multiphysics" "multipacting" "frequency detuning" "stiffening design"
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO076
About •	paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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THPO080	Design Validation of a Chopping and Deflecting System for the High Current Injector at IUAC	experiment, vacuum, diagnostics, power-supply	869
	S. Kedia, R. Ahuja, R. Kumar, R. Mehta IUAC, New Delhi, India
	A chopping and deflecting system has been designed and developed to provide the chopped beam with various repetition rates at the IUAC experimental facilities. It consists of four pairs of deflecting plates with increasing gap from 15 mm to 21 mm to maximize the effective electric field, preserve the beam emittance and to maximize the transmission efficiency within the same voltage conditions. The design of CDS has been validated with various simulation codes like CST MWS, Solid Works, Python and TRACE 3D. The deflecting plates have been fabricated, and assembled with in the design accuracy of 100 microns. A vacuum chamber has been designed and fabricated to incorporate the deflector plate assembly. The CDS unit has been installed in the Low Energy Ion Beam Facility at the IUAC to validate the design value of ion beam deflection. A slit has been installed to cut the deflected charge particles. Since the pulse power electronics required for chopping is presently under design we have used DC voltage across the four pairs of deflecting plates and amount of deflection was measured accordingly. The design, development, and DC beam test will be discussed in the article.
	Poster THPO080 [2.037 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO080
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO082	Physical Design of a Rectangular RF Deflector for Ultrashort Bunch Length Measurement	cavity, electron, FEL, coupling	872
	J. Bai, Q.S. Chen, K. Fan HUST, Wuhan, People’s Republic of China
	Cylindrical deflectors which are now widely used for bunch length measurement suffer from the degeneration of polarization, while rectangular deflectors can separate polarization mode easily. This paper is focused on the study of a one-cell rectangular deflector, which is considerably different from cylindrical structure or multi-cell structure. A one-cell structure is free of π mode restriction and can achieve higher deflection efficiency per unit length. The proposed scheme is expected to achieve time resolution better than 200fs with the driving power less than 1MW. Cavity optimization and beam dynamic simulation are introduced in this paper.
	Poster THPO082 [0.484 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO082
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO084	BPM Time of Flight Measurements for Setting-up the RF Cavities of the CERN Linac4	linac, cavity, DTL, electron	879
	M. Bozzolan CERN, Geneva, Switzerland
	The newly constructed H⁻ LINAC4 at CERN has recently completed its first extended reliability run. It is equipped with Beam Position Monitors (BPMs) based on shorted-stripline pick-up electrodes to measure both position and Time of Flight (ToF). The ToF, in turn used to calculate the kinetic energy of the beam, is determined through signal phase shift measurements between pairs of BPMs. ToF measurements are performed by scanning of the phase of the RF injected into the cavities to find the nominal RF settings for optimal beam acceleration. This paper focuses on the technical aspects of the ToF measurement as well as on the results obtained during beam commissioning and their comparison with beam dynamics simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO084
About •	paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019
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THPO090	The Analysis of Module Failure in High Solid-state Amplifier for High Current RFQ	scattering, experiment, rfq, cavity	886
	L.P. Sun, Y. He, G. Huang, C.X. Li, L. Lu, A. Shi, L.B. Shi, X.B. Xu, H.W. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	New accelerator RF system was upgraded to the solid-state amplifier in ADS project due to its stable, sustainable and reliable. Until now, newest 80kW SSA was adopted in IMP, operating in 162.5MHz, and over 120 power modules were combined through several synthesizers for 80kW output. but since too many modules were optimized for amplitude and phase in the same time, one or some failure of circulator will lead to injure of whole RF system, when wavelength meets a specific condition, injure would turn out severe accident and heavy loss. In this paper, analyzing and simulating the multi-level synthetic matrix was the important method for ADS accident happened in June 20. 2017, the failure simulated results for RF amplify links under the specific circumstances also was presented simultaneously.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO090
About •	paper received ※ 17 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019
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THPO096	Design Study of a High Efficiency Klystron for SuperKEKB Linac	klystron, cavity, gun, linac	901
	F. Qiu, S. Fukuda, S. Matsumoto, T. Matsumoto, T. Miura, T. Natsui KEK, Ibaraki, Japan
	The injector linear accelerator (linac) for the SuperKEKB particle accelerator requires a higher efficiency klystron than the currently used 50 MW, S-band, pulsed unit (PV3050/E3730), which operates at the same voltage, to increase the power redundancy. The efficiency is expected to improve from the currently observed 45% to more than 60%. We propose a type of high efficiency klystron using novel bunching mechanisms. The 1-D disk model based code is used for preliminary optimization of the tube parameters; these parameters are further checked by 2-D codes known as field charge interaction (FCI) and MAGIC. In this paper, the design consideration of the high efficiency klystron is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO096
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO100	Development of a 1.5 GHz High-power CW Magnetron for SRF Accelerator	cavity, electron, SRF, coupling	908
	L. Wenliang College of Engineering and Applied Sciences for Nanjing University, Nanjing, People’s Republic of China S. An, Y.J. Ke, S. Lingbin, Z. Pengjiao, L. Youchun, L. Zhao, B.Z. Zhou PLAI, Nanjing, People’s Republic of China J.Z. Li, L.P. Zhang, Hou, R. Rui ADS, Jiangsu Province, People’s Republic of China
	An 1.5 GHz, 13.5 kW CW high-power magnetron for a superconducting RF accelerator has been developed by Andesun Technology Group Co., Ltd. with Nanjing Sanle Electronic Information Industry Group Co., Ltd., in order to replace the klystron, that could reduce the power source cost to about one-third. The cavity, output power antenna and coupling door-nob have been optimized by using CST Studio. Testing results have shown that the resonance frequency and output power have met the requirements, and the efficiency of the magnetron is higher that 78.45%.
	Poster THPO100 [0.574 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO100
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO102	Design Studies of Output Window for CEPC Klystron	klystron, multipactoring, electron, operation	911
	Z.J. Lu, Y.L. Chi, S. Fukuda, G. Pei, S. Pei, S.C. Wang, O. Xiao, U. N. Zaib, Z.S. Zhou IHEP, Beijing, People’s Republic of China S. Fukuda KEK, Ibaraki, Japan
	A high power and high efficiency klystron of the 650MHz, 800kW CW klystron for the Circular Electron Positron Collider (CEPC) is designed and developed at IHEP. This paper presents the design and simulation for the high power coaxial window for it. Plan of the hot test (high power testing before installing to the klystron) are also described. Simulation software of CST, ANSYS and Multipac 2.1 are used for design of window microwave structure, thermal analysis and multipacting effects. We obtained the good simulation results successively; the coaxial window S-parameter analysis, has revealed a low reflection at the operating frequency of 650 MHz. The thermal simulation shows a good temperature distribution under the cw 800kW propagation; maximum temperature has been found to be 33 °C at ceramic with water cooling in the inner and outer conductor. The multipacting at the window is possible source of the failure and it is shown that multipacting has less chance to be happened on the surface of ceramic.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO102
About •	paper received ※ 12 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019
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THPO107	High Power Coupler R&D for Superconducting CH-cavities	cavity, linac, Windows, heavy-ion	920
	J. List, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany W.A. Barth, M. Heilmann, J. Salvatore, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	The upcoming demands of the future research programs at GSI exceed the technical opportunities of the existing UNIversal Linear ACcelerator (UNILAC). Besides, the machine will be exclusively used as an injector for FAIR (Facility for Antiproton and Ion Research) providing high power heavy ion beams at a low repetition rate for injection into the synchrotron. A new dedicated superconducting (sc) continuous wave (cw) Linac is crucial to keep the research program competitive. The first part of the cw-linac, comprising a 217 MHz multi gap Crossbar-H-mode (CH) cavity surrounded by two sc solenoids inside a cryostat, already served as a prototype demonstrating reliable operability in a realistic accelerator environment. A sufficient high power RF-coupling concept is needed to feed this newly developed cw-RF cavity with up to 5 kW of RF-power. A high power coupler test stand was recently built to provide for a testing environment; further upgrade measures of this test area are foreseen. This contribution deals with the recent coupler R&D for the demonstrator set up. Besides simulations of thermal losses at the coupler (inside the RF-cavity) will be shown as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO107
About •	paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019
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THPO109	A New Spherical Pulse Compressor Working with Degenerated "Whispering Gallery" Mode	cavity, coupling, GUI, collider	928
	Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People’s Republic of China A. Grudiev CERN, Geneva, Switzerland
	CLIC is focusing on the Compact Linear Collider. To obtain a relatively high accelerating gradient, CLIC utilizes Pulse Compressors to increase the input power of accelerators. This work is to make an alternative design for CLIC pulse compression scheme. There are several kinds of pulse compressor: SLED, BOC, SLED-Ⅱ, spherical pulse compressor and so on. Usually, a spherical cavity, including BOC, can offer a higher Q factor compared with a cylindrical cavity. This design utilizes a spherical cavity working with degenerated Whispering Gallery mode.
	Slides THPO109 [1.738 MB]
	Poster THPO109 [1.913 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO109
About •	paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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THPO111	The Test of RF Breakdowns of CPHS RFQ	rfq, pick-up, linac, proton	931
	W.B. Ye, C. Cheng, X. Guan, J. Shi, X.W. Wang, Q.Z. Xing, S.X. Zheng TUB, Beijing, People’s Republic of China M.C. Wang NINT, Shannxi, People’s Republic of China
	The high accelerating gradient is significant for a compact linear accelerator, and RF breakdowns is a limitation for the high gradient. This work aims to research RF breakdowns of a 325MHz proton Radio Frequency Quadrupole (RFQ) accelerator of the Compact Pulsed Hadron Source（CPHS）. The breakdown rate (BDR) of the RFQ has been measured. Breakdown waveforms have been recorded, which have been used for counting breakdown time distribution and analyzing the location of RF breakdowns.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO111
About •	paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO113	Design of 4 Ampere S-Band Linac Using Slotted Iris Structure for Hom Damping	linac, HOM, damping, target	934
	J. Pang, S. Chen, X. He CAEP/IFP, Mainyang, Sichuan, People’s Republic of China S. Pei, H. Shi, J.R. Zhang IHEP, Beijing, People’s Republic of China
	An S-band LINAC with the operating frequency of 2856 MHz and beam current of 4 A was designed for flash X-ray radiography for hydrodynamic test. The optimization of the parameters of the LINAC was processed to obtain the minimum beam radius and the maximum energy efficiency. For the purpose of reducing the beam orbits offset at the exit of LINAC, a slotted iris accelerating structure would be employed to suppress the transverse Higher Order Modes (HOMs) by cutting four radial slots in the iris to couple the HOMs to SiC loads. In this paper, we present the design of the LINAC and the results of beam dynamic analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO113
About •	paper received ※ 10 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019
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THPO118	Beam Transverse Coupling and 4D Emittance Measurement Simulation Studies for PITZ	emittance, quadrupole, coupling, gun	945
	Q.T. Zhao, M. Krasilnikov, H.J. Qian, F. Stephan DESY Zeuthen, Zeuthen, Germany Q.T. Zhao IMP/CAS, Lanzhou, People’s Republic of China
	The Photo Injector Test Facility at DESY, Zeuthen site (PITZ) was built to test and optimize high brightness electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. Although the beam emittance has been optimized and experimentally demonstrated to meet the requirements of FLASH and XFEL, transverse beam asymmetries were observed during operation of the RF guns. Based on previous studies [1], the beam asymmetries most probably stem from beam transverse coupling by quadrupole field errors in the gun section. A pair of normal and skew gun quadrupoles was successfully used for reducing the beam asymmetries in experiment. In this paper, we discuss the beam transverse coupling between X and Y planes due to quadrupole field errors and its impact onto horizontal and vertical rms emittance. Multi-quads scan and two quads with rotated slits scan were proposed to measure the 4D beam matrix for PITZ and tested by simulation, which will give the residual beam coupling after gun quadrupoles compensation and would be helpful for minimizing the 2D rms emittance experimentally.
	Poster THPO118 [1.521 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO118
About •	paper received ※ 08 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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THPO132	Study of the Electron Beam Transfer Line for the AWAKE RUN II Experiment at CERN	electron, plasma, experiment, emittance	962
	S.Y. Kim, M. Chung UNIST, Ulsan, Republic of Korea M. Dayyani IPM, Tehran, Iran S. Döbert CERN, Geneva, Switzerland
	Proton Beam-Driven Plasma Wakefield Accelerator (PBD-PWFA) has been actively investigated at CERN within the AWAKE experiments to study the electron beam acceleration using plasma wake fields of the order of GV/m. In the AWAKE RUN 1 experiment an electron beam with an energy of 19 MeV and a bunch length of 2.2 ps rms has been used for the first demonstration of electron beam acceleration in the plasma wake fields. It has been observed that the energy gain of the electron beam is up to 2 GeV, and electron capture efficiency is few percent. Higher capturing efficiency and emittance preservation could be achieved by making the electron beam short enough to be injected only into the acceleration and focusing phase of the plasma wake fields. The electron accelerator needs to be upgraded for AWAKE RUN 2 experiments to obtain a bunch length less than 100 fs which corresponds to a quarter of the plasma wavelength. Planned electron beam parameters for the AWAKE RUN 2 are a beam charge of 100 pC, and a beam energy larger than 50 MeV. In this paper, we show the electron beam parameters for RUN 2, and the parameters of the transfer line such as Twiss parameters, beam envelope, and emittance. UNIST, Ulsan, 44919, Korea Institute For Research in Fundamental Sciences, 19395-5531, Tehran, Iran CERN, Geneva 1211, Switzerland
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO132
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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FR1A01	Results From the 6D Diagnostics Test Bench at SNS	experiment, quadrupole, diagnostics, emittance	966
	B.L. Cathey ORNL RAD, Oak Ridge, Tennessee, USA A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov ORNL, Oak Ridge, Tennessee, USA
	Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This work has been partially supported by NSF Accelerator Science grant 1535312. This paper presents the method and results for measuring the full six-dimensional phase space of a low energy, high intensity hadron beam. This was done by combining four-dimensional emittance measurement techniques along with dispersion measurement and a beam shape monitor to provide the energy and arrival time components. The measurements were performed on the new Beam Test Facility (BTF) at the Spallation Neutron Source (SNS), a 2.5 MeV functional duplicate of the SNS accelerator front end. The results include a correlation the had not previously been observed.
	Slides FR1A01 [7.083 MB]
	Poster FR1A01 [1.742 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-FR1A01
About •	paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019
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Paper

Title

Other Keywords

Page

MOPO016

Narrow-Band Terahertz Generation from Beam Pipe with Helix Wires

electron, radiation, wakefield, impedance

65

D. Wang
TUB, Beijing, People’s Republic of China

We studied through analysis and numerical simulations the use of a relativistic electron bunch to drive a metallic beam pipe with helix wire inside, for the purpose of gen-erating narrow-band terahertz radiation. we have shown that the frequency is related to the radius of the pipe and that of the wire, thus one can generate a narrow-band radiation pulse with frequency tunable through this scheme with different pipes and wires. The total energy of a few milli-Joules. The pulse length tends to be on the order of hundreds of picoseconds. We have also shown that, if the pipe radius is tapered along its length, the generated pulse will end up with a frequency chirp.
*wangdan2016@mail.tsinghua.edu.cn
*yanlx@mail.tsinghua.edu.cn

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO016

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paper received ※ 12 September 2018 paper accepted ※ 15 January 2019 issue date ※ 18 January 2019

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MOPO018

Development of an Improved Capture Section for the S-DALINAC Injector*

cavity, electron, linac, gun

68

S. Weih, M. Arnold, J. Enders, N. Pietralla
TU Darmstadt, Darmstadt, Germany
D.B. Bazyl, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany

For the injector of the superconducting Darmstadt electron linear accelerator S-DALINAC, the design of a new capture cavity was recently completed. This beta-reduced structure will optimize the capture of low-energy electron bunches from the gun section and therefore improve the longitudinal beam quality of the injector beam, as simulations have shown. The existing cryomodule of the injector has to be modified for the installation of the new cavity. These modifications include adaptions of the tuner frame as well as modifications of other surrounding parts. To improve the diagnostics in the low-energy section, an energy-spread measurement setup is currently also under development. In this contribution the cryomodule modifications as well as simulation results for the longitudinal beam dynamics are presented.
*Work supported by DFG through GRK 2128 "AccelencE"

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO018

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO020

Beam Dynamics Studies and Instrumentation Tests for Bunch Length Measurements at CLEAR

experiment, gun, electron, radiation

74

L. Garolfi, M. Bergamaschi, R. Corsini, A. Curcio, S. Döbert, W. Farabolini, D. Gamba, I. Gorgisyan
CERN, Geneva, Switzerland
C. Bruni, P. Lepercq, H. Purwar, C. Vallerand
LAL, Orsay, France
W. Farabolini
CEA/DSM/IRFU, France

A new CERN Linear Electron Accelerator for Research (named CLEAR) has been installed as a general-purpose user facility to study novel accelerating techniques, high-gradient structures, instrumentation and irradiation experiments. CLEAR is a flexible accelerator that can provide high quality bunched electron beams with a wide range of beam parameters up to an energy of 220 MeV, offering several testing capabilities. Among all the potential applications, novel accelerating techniques, such as plasma acceleration and THz generation are considered. These applications require shorter bunches, down to the 100 fs level. This paper reports on beam dynamics studies and instrumentation tests to establish a bunch length of this order in CLEAR. The short bunches are generated using adiabatic bunching in the first accelerating structure. For bunch length diagnostic CLEAR is equipped with a streak camera and a transverse deflecting cavity. Alternatively a phase-scan of the last accelerating structure could be used as well to estimate the bunch length. The experimental results with respect to these different techniques are presented and compared with simulations.

Slides MOPO020 [0.864 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO020

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO066

Simulation of the Transitional Process in Accelerating Sections by Equivalent Circuit Method

coupling, operation, MMI, interface

145

S.V. Matsievskiy, V.I. Kaminskiy, Ya.V. Shashkov
MEPhI, Moscow, Russia

Nowadays linac accelerating RF systems design is usually done by the finite difference method. It provides high accuracy of calculations and freedom in topology choosing, but may draw considerable amounts of computer resources with long calculation times. Alternative to this method, equivalent circuit method exists. The basic idea of this method is to build a lumped element circuit, which with certain approximation acts as an original accelerating cell. It drastically reduces the number of equations to solve. This method is long known but usually only used for the particular accelerating structures when speed of calculation is a key-factor. Present paper describes a way to numerically simulate transition processes in arbitrary coupled accelerating cells using the equivalent circuit method. This approach allows simulating transitional processes in accelerating structures significantly faster and allows doing so for structures with high quality factor and many cells - a hard task for conventional transient solvers based on the finite difference method.

Poster MOPO066 [0.519 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO066

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paper received ※ 23 August 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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MOPO070

Construction of the Side-coupled Standing-wave e-Linac

cavity, linac, coupling, electron

151

S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
F. Abbasi
Shahid Beheshti University, Tehran, Iran
M. Bahrami, M. Lamehi
IPM, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran

Due to Iran’s growing need for accelerators in various applications, NSTRI electron linear accelerator project has been defined for medical and inspection applications. This accelerator is a 6 MeV side-coupled standing-wave that operate is π /2 mode in the frequency of 2998.5 MHz. In this paper the construction and measurement results of the tube of this accelerator are presented. The prototype tube was constructed from aluminum and was clamped with bolts. By using a network analyzer, electric and magnetic probes and a side-coupled cavity tuning method and a bead-pull measurement technique, RF measurements were carried out. The resonant frequency and quality factor have been achieved 2998.5 MHz and 7940 respectively .
low-energy accelerator, construction of linac, standing-wave linac

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO070

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paper received ※ 12 September 2018 paper accepted ※ 09 November 2018 issue date ※ 18 January 2019

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MOPO077

Design of the High Gradient Negative Harmonic Structure for Compact Ion Therapy Linac

linac, proton, coupling, operation

160

S.V. Kutsaev, R.B. Agustsson, A.Yu. Smirnov, A. Verma
RadiaBeam, Santa Monica, California, USA
A. Barcikowski, R.L. Fischer, B. Mustapha
ANL, Argonne, Illinois, USA

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE-SC0015717 and Accelerator Stewardship Grant, Proposal No. 0000219678
A novel concept for an Advanced Compact Carbon Ion Linac (ACCIL) that will deliver up to 1 pnA of carbon ions with variable energy from 45 MeV/u to 450 MeV/u in a 45 m footprint, has been developed by Argonne National Laboratory (ANL) in collaboration with RadiaBeam. The ACCIL will have a 35 MV/m real-estate accelerating gradients that became possible to achieve with the development of novel S-band high-gradient structures, capable of providing 50 MV/m accelerating gradients for particles with β>0.3. In particular, a β=0.3 structure based on the novel approach of operation at the first negative spatial harmonic with the increased distance between the accelerating gaps will be presented. This is the first attempt to reach such high gradients at such small velocities. RadiaBeam and ANL have demonstrated the feasibility of building this structure for accelerating carbon ions by means of advanced computer simulations and are currently working towards the fabrication of this structure for high power tests.

Slides MOPO077 [1.863 MB]

Poster MOPO077 [0.923 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO077

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO087

Cold Test of Hybrid RFQ Prototype

rfq, quadrupole, cavity, linac

184

P.Y. Yu, Y. He, C.X. Li, F.F. Wang, Z.J. Wang, B. Zhang
IMP/CAS, Lanzhou, People’s Republic of China

Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator, which is combined by four-vane RFQ structure and CH-DTL structure. It has higher energy gain rate compared to conventional RFQ, and it is more compact than traditional DTL. In order to research on process exploration and RF parameters of this structure, an aluminium prototype is developed. The cold test of Hybrid RFQ prototype is completed. This paper will present the results and analysis of the test.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO087

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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MOPO090

Measurements of the First Room Temperature CH Cavity for MYRRHA at IAP Frankfurt

cavity, resonance, status, rfq

193

K. Kümpel, S. Lamprecht, P. Müller, N.F. Petry, H. Podlech, S. Zimmermann
IAP, Frankfurt am Main, Germany

Funding: This work has been supported by MYRTE which is funded by the European Commission under Project-ID 662186.
The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project is a planned accelerator driven system (ADS) for the transmutation of long-living radioactive waste. A critical passage for the beam quality and especially for the emittance is the injector, which for the MYRRHA project consists of a 4-Rod RFQ, two Quarter Wave Rebunchers (QWR) and a total of 16 normal conducting CH-DTL cavities. The first installment of the MYRRHA injector in Louvein-La-Neuve (Belgium) will include an ion source, a RFQ, the QWRs and the first seven CH DTL cavities. This paper will report on the status of the low level tests on CHs 1 and 2 as well as on further developments on CHs 8-15.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO090

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO093

A Study of a Cooling Configuration for an OFHC Copper Rebuncher

cavity, linac, pick-up, vacuum

200

O. Mazor, M. Bukai, D. Nusbaum, J. Rodnizki
Soreq NRC, Yavne, Israel
E. Dyunin
Ariel University, Ariel, Israel
G. Ziskind
Ben-Gurion University in the Negev, Beer Sheva, Israel

Funding: Pazy Fund (Israel Atomic Energy commission) https://pazy.org.il
A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction for the MEBT of SARAF Phase II proton/ deuteron linac. The rebuncher is designed to bunch a 5 mA CW beam at 176 MHz. The required cavity voltage according to beam dynamics evaluation is 150 kV with a beam aperture diameter of 40 mm at a beam energy of 1.3 MeV/u with a Q value of 8000. Considering utilizing this cavity for enhancing the beam energy, the cooling configuration is explored for a cavity voltage of 300 kV, consuming 20 kW dissipated power, at a peak electric field of 16 MV/m, equivalent to the Kilpatrick limit. The electro magnetic study conducted with the CST RF simulation package was reproduced at ANSYS HFSS. The simulated dissipated power along the rebuncher for 20 kW forward power injected through the coupler port with the HFSS driven model were assigned to the ANSYS Fluent model to explore the resulted temperature map. Several evolved cooling configurations were studied, including cooling of the drift tubes. In this configuration the temperature rise along the cavity is in the range of 30 K. A detailed design of the four gap rebuncher is following this study.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO093

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paper received ※ 03 September 2018 paper accepted ※ 22 September 2018 issue date ※ 18 January 2019

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MOPO096

Realistic Modeling of MEBT for the New LANSCE RFQ Injector

DTL, emittance, quadrupole, rfq

211

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

The new RFQ-based proton injector at LANSCE requires a specialized medium-energy beam transfer (MEBT) after the RFQ at 750 keV due to a following long (~3 m) existing common transfer line that also transports H⁻ beams to the DTL entrance. The horizontal space for MEBT elements is limited because two beam lines merge at 18-degree angle. The MEBT includes two compact quarter-wave RF bunchers and four short quadrupoles with steerers, all within the length of about 1 m. The beam size in the MEBT is large, comparable to the beam-pipe aperture, hence non-linear 3D fields at large radii and field-overlap effects become important. With CST Studio codes, we calculate buncher RF fields and quadrupole and steerer magnetic fields, and use them for particle-in-cell beam dynamics modeling of MEBT with realistic beam distributions from the RFQ. Our results indicate significant emittance growth in MEBT not predicted by the standard beam dynamics codes. Its origin is traced mainly to the quadrupole edge fields; the buncher RF fields also contribute noticeably. Proposed design modifications improve the MEBT performance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO096

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paper received ※ 10 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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MOPO101

LINAC-multitool - an Open Source Java-toolkit

linac, cavity, GUI, MMI

217

M. Schwarz, D. Bade, J. Corbet, H. Podlech
IAP, Frankfurt am Main, Germany

Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR
Dedicating more precious time to advanced research instead of spending it towards timeconsuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute’s R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO101

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO116

Study on the Control Technology of Large-load Time Constant Accelerator Magnet Power Supply

controls, power-supply, collider, superconducting-magnet

239

X. Wang, F. Long
IHEP, Beijing, People’s Republic of China

With the increasing application of power supply to industrial system, digital control system has become the mainstream of modern industrial control system. The wide application of digital control system has also led to the rapid development of digital controller. In the field of accelerator magnet power supply, the adoption of digital closed-loop control has become a trend in recent years. Due to the system’s tracking and regulation characteristics, the output current will slowly track the change of the given value in the course of the given current gradually rising. When the system reaches steady state, the disturbance of the system requires the regulator to adjust at a faster rate to correct the impact of the disturbance on the system. Today’s digital power supply control method mainly reflected in when load time constant is large, interference or load change, the power output is prone to overshoot or adjust the time is long, so the tracking and adjustment features cannot be met simultaneously. Therefore, this paper will study the power supply digital control technology for large - load time constant and the independent control method of tracking and regulating.

Poster MOPO116 [0.307 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO116

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paper received ※ 21 August 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

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MOPO119

Design of a Fully Automated Test Bench for Measuring the Field Distribution in Standing Wave Cavity

cavity, coupling, controls, network

246

Y. Lu, G. Feng, T. Hu, J. Jiang, X.D. Tu, Y.Q. Xiong
HUST, Wuhan, People’s Republic of China

The resonant cavity plays a great role in the linear accelerator. An accurate measurement of the cavity field distribution is very important to design linear accelerators. A fully computer controlled bench for the electric field distribution has been developed in this context. Based on the perturbation theory, the acquisition of the resonant frequency shift is proportional to the square of E (electric field). In order to verify the reliability of the test bench, a standard cylindrical cavity has been tested in this measurement system. The simulation by HFSS (High Frequency Structure Simulator) and the practice will be both presented in this paper. And the result demonstrates that, because of its high concentricity, the automated test bench achieves high precision in measuring the distribution of electric field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO119

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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MOPO127

Recent Results from MICE on Multiple Coulomb Scattering and Energy Loss

scattering, emittance, detector, radiation

267

J.Y. Tang
IHEP, Beijing, People’s Republic of China
J.C. Nugent
University of Glasgow, Glasgow, United Kingdom

Funding: STFC, DOE, NSF, INFN, CHIPP and more
Multiple Coulomb scattering and energy loss are well known phenomena experienced by charged particles as they traverse a material. However, from recent measurements by the MuScat collaboration, available simulation codes (GEANT4, for example) are known to overestimate the scattering of muons in low Z materials. This is of particular interest to the Muon Ionization Cooling Experiment (MICE) collaboration which has the goal of measuring the reduction of the emittance of a muon beam induced by energy loss in low Z absorbers. MICE took data without magnetic field suitable for multiple scattering measurements in the fall of 2015 with the absorber vessel filled with xenon and in the spring of 2016 using a lithium hydride absorber. In the fall of 2016 MICE took data with magnetic fields on and measured the energy loss of muons in a lithium hydride absorber. These data are all compared with the Bethe-Bloch formula and with the predictions of various models, including the default GEANT4 model.
Submitted by the MICE speakers Bureau. If accepted a member of the collaboration will be selected for the mission

Poster MOPO127 [0.842 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO127

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paper received ※ 19 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

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MOPO132

The 7 MeV APF DTL for Proton Therapy

DTL, proton, rfq, injection

277

X.C. Xie, D.M. Li, X. Li, Y.H. Pu, J. Qiao, M.H. Zhao, Z.T. Zhao
SINAP, Shanghai, People’s Republic of China
Y.H. Pu, X.C. Xie, F. Yang
Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China

Funding: This work is fund by Ministry of Science and Technology of the People’s Repulic of China, under Grant Number 2016YFC0105408
A 7MeV alternating phase focused (APF) drift tube linear (DTL) for proton therapy has been designed, and a design code has been developed based on a sinusoidal synchronous phase formula and a linearly increasing electrode voltage assumption. The design procedure includes the radio frequency quadrupole (RFQ) to drift tube linac (DTL) matching, and end-to-end simulation that conducted by Trace Win. Moreover, a cutting method has been performed to correct the integral electric field deviation of RF gaps.

Slides MOPO132 [4.219 MB]

Poster MOPO132 [2.604 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO132

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paper received ※ 20 August 2018 paper accepted ※ 15 January 2019 issue date ※ 18 January 2019

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TUPO004

RF Design and Cold Model Measurement of an IH-DTL for HIMM Injector

DTL, cavity, linac, quadrupole

329

H. Du, Q.Y. Kong, Z.S. Li, K.D. Wang, X. Yin
IMP/CAS, Lanzhou, People’s Republic of China

An interdigital H-mode drift tube linac (IH-DTL) will be constructed as a postinjector linac for the Heavy Ion Medical Machine (HIMM). Its resonant frequency, injec-tion and final energies are determined from beam dynamics and hardware parameters considerations of the entire machine to be 162.5MHz, 600keV/u and 4MeV/u, respectively. The beam duty cycle of the injector linac is less than 0.1% based on the injection requirements of the synchrotron. Beam dynamics and RF structure design and optimize of the IH-DTL has been finished. The maximum surface electric field is less than 2.0-times the Kilpatric limit for accelerating C⁴⁺ beam. This IH-DTL contains 42 accelerating gaps and two focusing quadrupole triplets. In order to examine the field distribution of the IH-DTL which reaches the length of 3.17m, an aluminum alloy 1:1 cold model cavity with 4 moveable tuners and 2 empty focusing magnet shell was constructed. The relative intertube-distance errors are less than ±50μm. The measurements show that the gap voltage values can match the CST-MWS simulating results within relative difference of ±3% by adjusting the 4 moveable tuners.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO004

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO010

Muon Acceleration Test with the RFQ Towards the Development of the Muon Linac

experiment, acceleration, rfq, diagnostics

342

R. Kitamura
University of Tokyo, Tokyo, Japan
S. Bae, S. Choi, B. Kim
SNU, Seoul, Republic of Korea
Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, T. Yamazaki
KEK, Tsukuba, Japan
K. Hasegawa, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Iijima, Y. Sue
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
H. Iinuma, Y. Nakazawa
Ibaraki University, Hitachi, Ibaraki, Japan
K. Ishida
RIKEN Nishina Center, Wako, Japan
S. Li
The University of Tokyo, Graduate School of Science, Tokyo, Japan
M. Otani, N. Saito
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
G.P. Razuvaev
Budker INP & NSU, Novosibirsk, Russia

The muon linac to accelerate muons 212 MeV is planned in order to measure the muon dipole moments precisely in the J-PARC. The muon acceleration with a RF accelerator hasn’t been demonstrated yet in the world. Therefore the muon acceleration test with the RFQ as the feasibility test of the muon linac was demonstrated at the Muon D line in the J-PARC MLF. Conventional muons are cooled with producing ultra-slow muons using the muonium production and the ionization laser for the muon linac. However these apparatuses couldn’t be used because of the limitation of the experimental area in the acceleration test. Therefore the conventional muon was converted to the negative muonium ion (Mu-) with less than 2 keV using the thin aluminum foil target as the easy cooling method. The Mu- was finally accelerated to 90 keV using the RFQ. The accelerated Mu- was selected with a diagnostic beam line and identified with the Time-Of-Flight measurement using a MCP detector. The result of the world’s first muon acceleration test with the RFQ will be reported in this presentation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO010

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO016

High Frequency RFQ Design and LEBT Matching for the CERN TwinEBIS Ion Source

rfq, emittance, gun, space-charge

358

V. Bencini, J.-B. Lallement, A.M. Lombardi, H. Pahl, J. Pitters, F.J.C. Wenander
CERN, Geneva, Switzerland
M. Breitenfeldt
AVO-ADAM, Meyrin, Switzerland
A.I. Pikin
BNL, Upton, Long Island, New York, USA

An Electron Beam Ion Source (EBIS) is being developed at CERN for production of highly charged ions, for instance fully stripped 12C. The focus has so far been on the electron gun design, aiming for a high current compression, which results in a rapid ionisation process and thereby high repetition rate. Initial commissioning tests of such an electron gun, the so-called MEDeGUN, have already been performed and we are now in the process of designing a multi-purpose ion extraction and diagnostics line. The Low Energy Beam Transport (LEBT) line will transport the ions into the downstream Radio Frequency Quadrupole (RFQ) with a nominal energy of 15 keV/u. The 750 MHz RFQ is designed to accelerate ions from 15 keV/u up to the final energy of 2.5 MeV/u. After the RFQ design was finalized and its acceptance calculated, the beam matching to the RFQ was studied, finding a set of parameters for the LEBT that maximize the transmission through the RFQ. Details of the RFQ design, of the LEBT matching procedure and its final results are illustrated in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO016

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paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO023

Preserving Micron Tolerances Through the Assembly Process of an X-band Accelerating Structure

cavity, HOM, linac, software

377

J. Sauza-Bedolla, N. Catalán Lasheras, A. Grudiev, S. Lebet, E. Rodriguez-Castro, P. Sobrino-Mompean, A. Solodko, K. T. Szypula
CERN, Geneva, Switzerland
H. Bursali
IZTECH, Izmir, Turkey

The CLIC structures are designed for operating at X-Band, 2π/3 traveling wave mode with a loaded 100 MV/m gradient. Mechanical tolerances, at the submicron level, are required to satisfy the RF design constraints and beam dynamics and are reachable using ultra-precision diamond machining. However, inherent to the manufacturing process, there is a deviation from the nominal specifications and as a result; incorrect cavity dimensions produce a less efficient linac. Moreover, the assembly process increase the difference from the original geometry. As part of a cost and manufacturability optimization of the structures for mass production, this study aims to identify a correlation between frequency deviations and geometrical errors of the individual discs of the accelerating structures caused by the production process. A sensitivity analysis has been carried out to determine the most critical parameters. Cell frequency deviations have been monitored by bead pull measurements before and after bonding. Several accelerating structure prototypes have been tested to determine our assumptions and to assess if the assembly process preserves the tight tolerances achieved by machining.

Poster TUPO023 [1.443 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO023

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paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO039

Tests of the Balloon Single Spoke Resonator

cavity, multipactoring, linac, TRIUMF

417

Z.Y. Yao, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, H. Liu, Y. Ma, B. Matheson, B.S. Waraich, Q. Zheng, V. Zvyagintsev
TRIUMF, Vancouver, Canada

A balloon variant of the single spoke resonator (SSR) has been designed, fabricated and tested. The cavity is the SSR1 prototype for the Rare Isotope Science Project (RISP) in Korea. It is specifically designed to reduce the likelihood of multipacting barriers near the operating point. A systematic multipacting study leads to a novel geometry, a spherical cavity with re-entrant irises and a spoke. Other than eliminating multipacting around operational gradient, the balloon shape also provides competitive RF parameters and robust mechanical structure. Cryostat cold tests demonstrated cavity performance on each design aspect. The cold tests will be reported in this paper.

Slides TUPO039 [25.279 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO039

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paper received ※ 17 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO051

Design Considerations of a Balloon-shaped SSR Superconducting Cavity

cavity, electron, distributed, superconducting-cavity

448

H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, S. H. Park, J.Y. Yoon
Korea University Sejong Campus, Sejong, Republic of Korea

A single spoke resonator (SSR, β = 0.51 and f = 325 MHz) is being developed at Korea University. It is well-known that a traditional spoke cavity having flat or round end walls has broad multipacting ranges in acceleration gradient, sometimes including operation region. In general, quite long conditioning time is consumed to overcome such multipacting barriers. In this study, we introduce a balloon-shaped SSR superconducting cavity for the multipacting mitigation due to structural simplicity. The electromagnetic modeling of the SSR was made based on the RF parameter optimization. The simulation results show much narrower multipacting bandwidth, compared to those for the traditional spoke cavity. Mechanical analyses with stiffening structure at maximum allowable working pressures indicate acceptable stresses at the SSR cavity wall. In addition, the resonant frequency shifts due to fabrication and processing for cold tests are predicted and power coupling and tuning mechanism are also investigated.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO051

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paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO052

Design Study of a Prototype 325MHz RF Power Coupler for Superconducting Cavity

pick-up, cavity, superconducting-cavity, resonance

451

J.Y. Yoon, J.B. Bhang, H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, C.S. Park, S. H. Park
Korea University Sejong Campus, Sejong, Republic of Korea
E. Kako
KEK, Ibaraki, Japan
D.Y. Kim, J. Lee
Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea
I. Shin
IBS, Daejeon, Republic of Korea

Funding: Korea University (Sejong Campus) in South KOREA
We present design studies of a prototype RF input power coupler, which provides RF powers to 325MHz cavities up to 18.5 kW in CW mode. The prototype power coupler is a coaxial capacitive type with single ceramic window. In order to optimize the RF coupler design, we performed multi-physics simulations, including electromagnetic, thermal, and mechanical analyses.

Poster TUPO052 [1.607 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO052

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO083

Beam Dynamics for the FAIR p-Linac Ladder RFQ

rfq, linac, emittance, ion-source

522

M. Syha, U. Ratzinger, M. Schuett
IAP, Frankfurt am Main, Germany

After the successful measurements with a 0.8 m prototype a 3.3 m Ladder-RFQ is under construction at IAP, Goethe University Frankfurt. It is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the p-Linac at FAIR. Along the acceleration section modulation parameter, aperture and synchronous phase all course (quasi-)linear, which differentiates this design approach from other designs developed at IAP. The ratio of transversal vane curvature radius to mid-cell radial aperture as well as the vane radius itself are constant, which favors a flat voltage distribution along the RFQ. This was verified by implantation of the modulated vane geometry into MWS-CST RF field simulations. The development of adequate beam dynamics was done in close collaboration with the IAP resonator design team. The Los Alamos RFQGen-code was used for the RFQ design and the beam dynamics simulations.

Poster TUPO083 [0.932 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO083

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paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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TUPO085

Modelling of Beam Parameters of RF Linac for GBS-ELI-NP

linac, quadrupole, gun, emittance

528

P.S. Tracz
IFIN-HH, Bucharest - Magurele, Romania

The Gamma Beam System at the ELI-NP (Extreme Light Infrastructure - Nuclear Physics) currently being constructed in Magurele/Bucharest, Romania will be a high-brilliance advanced source of gamma rays based on laser Compton back-scattering. For a successful operation of the GBS a high brightness low emittance electron beam is of crucial importance. The warm RF linac is designed in two stages - one with the beam up to 300 MeV, and another one about 720 MeV. The S-band photo-injector is combined with a C-band linac. The beam is transported by transfer lines to the interaction points. In this paper we report the results of computer simulations of the electron beam transport in the low energy linac and transfer line up to the low energy interaction point (IP1). The simulation model makes it possible to predict the beam parameters to be recuperated in case of failure of any magnetic or accelerating elements as well as it enables to determine the optimal parameters of replaced components. It will be used for the development of the Gamma Beam System in the future.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO085

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO092

Beam Dynamics and Collimation Following MAGIX at MESA*

target, electron, scattering, radiation

540

B. Ledroit, K. Aulenbacher
IKP, Mainz, Germany

Funding: * Supported by the DFG through GRK 2128
The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing operation in energy-recovery linac (ERL) mode, where beam energy is recovered by decelerating the beam in linac cryomodules and transferring kinetic energy to the RF. The ERL mode provides the opportunity to operate experiments at peak energy with thin targets, combining high luminosities typical for storage rings and high beam brightness typical for linacs. The MESA Internal Gas Target Experiment (MAGIX) aims to operate jet targets at high luminosities with different gases up to Xenon. As scattering effects in the beam rise with the atomic number, investigations on the impact of the target on beam dynamics and beam losses are required for machine safety. The goal of this work is to understand target induced halo, track halo particles through downstream sections and protect the machine with a suitable collimation system and shielding from direct and indirect damage through beam losses and radiation. The present status of the investigations is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO092

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paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TUPO093

Excitation of Millimeter Wavelength Cavity Structure

cavity, gun, cathode, emittance

543

M.V. Arsentyeva
NSU, Novosibirsk, Russia
A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia

Excitation of millimeter wavelength cavity structure In this work excitation of W-band structure is studied. The structure consists of cylindrical cavities with the operating frequency of about 96 GHz. We plan to excite the structure by short bunches from the photocathode RF gun. In order to choose structure geometry and beam duration, we performed estimations and simulations; induced voltage was also estimated. Taking into account feasible parameters of the photocathode RF gun such as beam size and emittance, we studied exciting beam transverse dynamics to define its other characteristics (energy and charge). To lead the beam from the whole structure, focusing is needed. After estimation of required magnetic field, we considered possibility of focusing with help of permanent magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO093

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paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO095

Beam Loading with the First Rebuncher of Spiral2, First Measurements

cavity, controls, experiment, linac

546

M. Lechartier, R. Ferdinand, J.F. Leyge
GANIL, Caen, France

In the SPI2 project the middle energy line (LME) is equiped with a radio frequency qupole and three Rebunchers. The subject of this article is to measure and characterise the effect of the beam loading on the first Rebuncher cavity.

Poster TUPO095 [1.146 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO095

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paper received ※ 20 September 2018 paper accepted ※ 15 January 2019 issue date ※ 18 January 2019

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TUPO109

Electron Cloud Estimates for the Jefferson Lab EIC

electron, sextupole, proton, dipole

563

K.E. Deitrick, V.S. Morozov, T. Satogata
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In this work, we present preliminary estimates for electron cloud build-up and saturation for the ion ring of the Jefferson Laboratory Electron-Ion Collider (JLEIC) currently under development. Using the baseline ion ring design, we study the impact of various operational parameters on the behavior of the electron cloud for a 100 GeV proton beam, including estimated tune shifts.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO109

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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TUPO113

Beam Dynamics Studies Through Dielectric THz Accelerating Structures

GUI, vacuum, accelerating-gradient, linac

569

R. Apsimon, G. Burt, A.L. Healy, S.P. Jamison
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R.B. Appleby, E.J.H. Smith
UMAN, Manchester, United Kingdom
A. Latina
CERN, Geneva, Switzerland

As conventional RF accelerating schemes approach the physical limit of accelerating gradient, the accelerator community is increasingly looking at novel accelerating techniques to overcome these limitations. Moving from the RF to the THz frequency range, higher acceleration gradients of high energy beams can be achieved in compact structures. Beam dynamics studies are crucial as part of the design of novel accelerating structures to maximise the output beam current as well as the accelerating gradient. In this paper we present beam dynamics simulations through dielectric lined waveguide structures using novel techniques to simulate broadband signals for particle tracking studies in RF-Track. The beam parameters through the structure are optimised and we study the dynamics of general broadband accelerating structures.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO113

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paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TUPO120

The Study of the Length and Shape of Beam in a High Power Electron Accelerator

electron, radiation, extraction, industrial-accelerators

584

M. Salehi, F. Abbasi Davani, B.G. Ghasemi
Shahid Beheshti University, Tehran, Iran
F. Ghasemi, A.P. Poursaleh
NSTRI, Tehran, Iran

The output beam of a high-power linear accelerator, used for industrial purposes, is irradiated on products and scanning them. In order to improve the dosimetry of radiation which products received and to prevent loss of the attacked- beams to the edge of products, the exact evaluation of scanning length is necessary . One of the other challenges of the scanning beam is the lack of uniformity in dosimetry of received radiation . The scanning beam does not collide in parallel to the products, which is also a challenge to accelerator efficiency. To improve dosimetry of received radiation, the use of trajectory correction magnets is suggested. These magnets correct the beams that do not scan in parallel. Also, using the Monte Carlo code, the dosing rate of received radiation to products is simulated and compared in two non-uniform and uniform modes (corrected by trajectory correction magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO120

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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TH1A03

High Brightness Electron Beams from Plasma-based Acceleration

plasma, electron, acceleration, FEL

637

A. Marocchino, A. Biagioni, E. Brentegani, E. Chiadroni, M. Ferrario, F. Filippi, A. Giribono, R. Pompili, A.R. Rossi
INFN/LNF, Frascati (Roma), Italy
A. Bacci
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy

Funding: INFN-CNAF and CINECA for high performance computing resources. European Union Horizon 2020 programme N. 53782.
Plasma Wakefield acceleration is a promising new acceleration techniques that profit by a charged bunch, e.g. an electron bunch, to break the neutrality of a plasma channel to produce a wake where a trailing bunch is eventually accelerated. The quest to achieve extreme gradient conserving high brightness has prompted to a variety of new approaches and techniques. Most of the proposed schemes are however limited to the only plasma channel, assuming in the vast majority of cases, ideal scenarios (e.g. ideal bi-gaussian bunches and uniform density plasma channels). Realistic start-to-end simulations, from the photo-cathode to FEL via a high gradient, emittance and energy spread preserving plasma section, are mandatory for paving the way towards plasma-based user facilities.

Slides TH1A03 [25.814 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1A03

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paper received ※ 11 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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TH1A05

Jitter Study for the APS Linac Photo-injector Beam

laser, timing, linac, experiment

647

D. Hui, M. Borland, J.M. Byrd, Y. Sun
ANL, Argonne, Illinois, USA

Funding: *Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Linac photo-injector can deliver high brightness electron beams to the Linac Extension Area (LEA) for beam experiments such as TESSA (Tapering Enhanced Stimulated Superradiant Amplification). Beam jitter in the device-under-test (DUT) area of the LEA can adversely affect the quality of data for such experiments. In this paper, a start-to-end simulation of jitter is studied. Sources of jitter include photo-cathode drive-laser arrival time, laser energy, and RF phases and voltages of the photo-cathode gun and accelerating cavities. It is found that at the DUT the relative mean energy jitter is the most significant concern, and that improvements in the Linac RF voltage stability can help to reduce it. RMS energy spread are more sensitive to the laser timing and charge jitter. The laser timing jitter itself can be compressed by the magnetic chicane by a factor of 5.6.

Slides TH1A05 [4.377 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1A05

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paper received ※ 10 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO003

L-band Resonant Ring for Testing RF Windows for ILC

collider, coupling, klystron, linear-collider

679

B. Du, N. Liu
Sokendai - Hayama, Hayama, Japan
T. Matsumoto, S. Michizono, T. Miura, F. Qiu
KEK, Ibaraki, Japan
T. Matsumoto, T. Miura, F. Qiu
Sokendai, Ibaraki, Japan

A resonant ring is widely used for the breakdown test of RF components under high power. It can reach power gain of more than 10dB, which is limited by the attenua-tion of the ring. An L-band resonant ring is constructed for testing RF components of International Linear Collid-er (ILC) which is based on an RF frequency of 1.3GHz. The target of the high power test is 5 MW. We have fin-ished the test of an input power of 500 W using a solid state amplifier, and the principle of the resonant ring is verified. The resonant ring is tuned to an optimal condi-tion, which is preparation for high power operation. This paper details the principle, construction, and test of the L-band resonant ring.

Poster THPO003 [2.301 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO003

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paper received ※ 13 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO005

High Aspect Ratio Beam Generation with the Phase-space Rotation Technique for Linear Colliders

emittance, gun, collider, linear-collider

685

M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J.G. Power
ANL, Argonne, Illinois, USA
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan
H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

Funding: This work is partly supported by Grant-in-Aid for Scientific Research (B) and US-Japan Science and Technology Cooperation Program in High Energy Physics.
Linear colliders is the only way to realize e⁺ e⁻ collision at higher energy beyond the limit of ring colliders by the huge synchrotron radiation energy loss. In the linear collider, the beam current should be much smaller comparing to the ring collider to save the required electricity. A way to realize an enough luminosity with the small beam current and less energy spread by Beamstrahlung, is collision in flat beam. This high aspect ratio beam can be made by phase-space rotation technique instead of the conventional way with DR (Damping Ring). We present a simulation of this technique and pilot experiments at KEK-STF and ANL WFA.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO005

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO007

MESA - Status of the Implementation of the MicroTCA.4-based LLRF Control System

cavity, controls, LLRF, experiment

691

J.N. Bai, K. Aulenbacher, J. Diefenbach, F. Fichtner
IKP, Mainz, Germany
P. Echevarria
HZB, Berlin, Germany
R.G. Heine
KPH, Mainz, Germany

MESA at the Institut für Kernphysik (KPH) at Johannes Gutenberg-Universität Mainz is a multi-turn energy recovery linac (ERL), aiming to serve as user facility for particle physics experiments. The RF-accelerating systems of MESA consist of four 9-cell TESLA superconducting cavities, four normal conducting (NC) pre-accelerator cavities, two NC buncher cavities and two NC chopper cavities. They operate in continuous wave (CW) mode. In order to control the radio frequency (RF) amplitude and phase within the 12 cavities with the required accuracy and stability in the range of better than 0.01% and 0.01°, the MicroTCA.4 based digital low-level RF (LLRF) control system based on the development at DESY, Hamburg will be well adapted for the MESA cavities. In this paper, we describe the theoretical modelling of superconducting cavity and PID controller in SIMULINK which is useful to find the suitable control parameter for the PID controller and to predict the system performance. The progress to date of the implementation and tests of the LLRF system at MESA will also be presented.

Poster THPO007 [1.274 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO007

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paper received ※ 11 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019

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THPO010

Novel Straight Merger for Energy Recovery Linacs

cavity, dipole, experiment, electron

702

K.E. Deitrick, A. Hutton
JLab, Newport News, Virginia, USA
A.C. Bartnik, C.M. Gulliford
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.A. Overstreet
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One of the most critical design considerations for an energy recovery linac (ERL) is how to merge the injected bunch onto the linac axis with minimal beam degradation. All merger designs in established and upcoming machines involve significant bending of the injected beam ’ even using a so-called straight merger bends the injected beam several degrees. We propose a merger which reduces the bending of the injected beam by an order of magnitude. By passing both beams through a septum magnet followed by an rf separator cavity with a superimposed dipole magnetic field, the injected beam bends minimally within the cavity, while the recirculated beam bends to align with the linac axis. Here we describe the concept in detail and present simulation results to demonstrate the advantages of such a design, particularly for magnetized beams or minimal energy separation between the injected and recirculated beams. Measurements from an experiment at CBETA evaluating the beam dynamics of the rf separator are presented and compared with simulation results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO010

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO012

Once Recirculating Energy Recovery Linac Operation of S-DALINAC*

linac, operation, acceleration, recirculation

710

M. Arnold, J. Birkhan, J. Pforr, N. Pietralla, F. Schließmann, M. Steinhorst
TU Darmstadt, Darmstadt, Germany
F. Hug
KPH, Mainz, Germany

Funding: *Work supported by DFG through GRK 2128 and INST163/383-1/FUGG
Since 1991 the superconducting S-DALINAC is running in recirculating operation. It was built in a twice recirculating layout. A third recirculation beam line was added in 2015/2016 as an upgrade. The new recirculation beam line is installed in-between the two existing beam lines. It houses a path length adjustment system capable of changing the length of the orbit for recirculation by up to 10 cm corresponding to the RF wave length at the operation frequency of 3 GHz and consequently to a freedom of RF phase adjustment by 360°. The new beam line can, thus, be utilized for an accelerating operation or, if the change in phase is set to 180°, for an energy recovery linac (ERL) operation. In August 2017 the S-DALINAC was first operated in once recirculating ERL mode and became the first running ERL in Germany. Different aspects of this ERL run have been observed and were evaluated. The layout of the S-DALINAC allows a once or twice recirculating ERL mode. Beam dynamics simulations for both modes have been conducted or are currently under investigation. This contribution will discuss the once recirculating ERL operation, its results, and future plans concerning ERL measurements.

Poster THPO012 [0.708 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO012

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO026

The Multi-physics Analysis of Dual-beam Drift Tube Linac

DTL, cavity, operation, linac

735

T. He, L. Lu, W. Ma, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang
IMP/CAS, Lanzhou, People’s Republic of China

The DB-DTL prototype is proposed to validate the fea-sibility of multi-beam accelerator in middle energy region. The main parameters are listed in Table.1. The DB-DTL will operate as pulse injector with the capacity of accelerating proton from 0.56 MeV to 2.5 MeV. The 35.83 kW normalized power dissipation of DB-DTL dis-sipated on the cavity internal surface will heat the cavity and cause cavity temperature rise and structural defor-mation, which will lead to resonant frequency shifting. The cooling water takes away the power to resolve this problem. In this paper, detailed multi-physics field simu-lation of DB-DTL is performed by using ANSYS multi-physics, which is a coupled electromagnetic, thermal and structural analysis.

Poster THPO026 [0.759 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO026

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO029

Quality Factor and Power Loss of the CSNS DTL

cavity, DTL, operation, linac

741

P.H. Qu, M.X. Fan, A.H. Li, B. Li, J. Peng, Y. Wang, X.L. Wu
CSNS, Guangdong Province, People’s Republic of China
Q. Chen, K.Y. Gong, H.C. Liu
IHEP, Beijing, People’s Republic of China

An Alvarez-type Drift tube linac (DTL) was utilized to accelerate the H⁻ ion beam of up to 15mA peak current from 3 to 80MeV of China Spallation neutron source (CSNS). For ease of manufacturing and measurement, the CSNS DTL was divided into four independent cavities. The Q factor of four cavities were given, including the measurement results of low-power[1] and high-power[2], and several reasons for the low Q factor of the cavity in the measurement process were analysed. During the op-eration of the DTL, the frequent alarm of the water flow switch causes the power of the cavity to fall to 0. Esti-mate the power loss of each component, under the cir-cumstances of ensuring adequate water flow, reduce the alarm threshold of the water flow switch of some compo-nents to improve the stability of the system.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO029

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paper received ※ 22 August 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO035

Tuning and Low Power Test of the 325 MHz IH-DTL at Tsinghua University

DTL, proton, linac, cavity

759

R. Tang, C.T. Du, X. Guan, Y. Lei, P.F. Ma, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, W.B. Ye, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People’s Republic of China
J. Li
NUCTECH, Beijing, People’s Republic of China

An interdigital H-mode drift tube linac (IH-DTL), which accelerates proton beam from 3 MeV to 7 MeV has been designed and assembled at Tsinghua University. There are 8 plungers in the 1 m tank and one co-axial coupler is used to feed the power. The frequency is tuned to 325 MHz. The field distribution is measured by the bead perturbation method. Finally, the gap voltage error has been tuned to be smaller than ±3.0%, which satisfies the design requirement. The Q factor of the tank is 7000 while the power dissipation is 244 kW. Details of the low power test is presented.

Poster THPO035 [1.268 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO035

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO042

An Optimization Method of the Nose-cone Buncher Cavity

cavity, proton, radiation, bunching

778

W.L. Liu, P.T. Cong, Z.M. Wang
NINT, Shannxi, People’s Republic of China
H. Jiang, S.X. Zheng
TUB, Beijing, People’s Republic of China

The nose-cone buncher cavity is widely used on proton accelerators. It’s important to properly optimize the cavity geometry for fine RF performance. Howev-er, currently the optimization is usually carried out manually and the criteria are not objective enough. In this paper, an optimization method using the multi-objective, multi-variable optimization approach is presented. The geometry and RF parameters are con-sidered as the variables and objectives respectively. The goal function is defined as the weighted sum of multiple RF parameters. The multi-variable functions are approximately derived from the single-variable functions based on electromagnetic simulation. And an optimization code is developed accordingly which has been applied to the XiPAF debuncher optimization.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO042

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO049

Field Tuning of a Radio-frequency Quadrupole Using Full 3D Modeling

rfq, cavity, insertion, linac

798

T. Morishita, K. Hasegawa, Y. Kondo, H. Oguri
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Otani
KEK, Ibaraki, Japan

The radio-frequency quadrupole linac (RFQ) is operating in the frontend of the J-PARC linac to accelerates 50 mA negative hydrogen beams from 0.05 MeV to 3 MeV. As a backup, the spare RFQ has been fabricated in 2018. The vane-voltage ramping is adopted to improve the acceleration efficiency so that the cross-sectional shape is adjusted longitudinally to produce the designed voltage distribution. Then, the three-dimensional cavity models including modulations and cutbacks were created in CST Micro-Wave Studio. The vane-base widths and cutback depths were optimized to produce the desired vane-voltage distribution. In the final tuning, the heights of the stub turners were also determined based on the tuner responses obtained from the full 3D models. In this paper, the detailed design process of the cavity dimensions and the result of the low-power measurements are described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO049

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO050

Research on the New Cavity Structure of RFQ Accelerator With Bent Vanes at IMP

rfq, cavity, impedance, ECR

802

L. Yang, T. He, Y. He, C.X. Li, L. Lu, L.P. Sun, C.C. Xing
IMP/CAS, Lanzhou, People’s Republic of China
L. Yang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

A new cavity structure of RFQ accelerator with bent vanes is proposed to meet the miniaturization requirement of low frequency heavy ion accelerators at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The new structure has a downsized cross section by bending vanes while keeping a certain vane lengths. It also possesses the advantages of simple cooling structure and high power efficient when used in low frequency. The new structure has obvious advantages in reducing manufacturing difficulty of cavity, cutting down project cost, enhancing facility reliability and stability.

Slides THPO050 [1.407 MB]

Poster THPO050 [0.398 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO050

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO051

The Multi-physics Analysis of LEAF RFQ

rfq, cavity, radio-frequency, quadrupole

805

X.B. Xu, T. He, Y. He, C.X. Li, L. Lu, W. Ma, A. Shi, L.B. Shi, L.P. Sun, C.C. Xing, L. Yang, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

The 81.25 MHz CW RFQ is designed to accelerate heavy ions with Q/A from 1/7 to 1/2 at 0.5 MeV/u for the Low Energy Accelerator Facility (LEAF) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). The four-vane RFQ consists of six mod-ules with a total length of 5.95 meters, For the CW oper-ating mode, thermal management will be a very important issue, Therefore a multi-physics analysis is necessary to ensure that the cavity can stably operate at the high RF power . The multi-physics analysis process includes RF electromagnetic analysis, thermal analysis, mechanical analysis, and the frequency shift, the cooling water system is used for frequency tunning by the temperature adjustment, and also analyze RFQ undercuts, fixed tuners, and pi-mode rods, the results show that the thermal and structural design of this RFQ is reasonable.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO051

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paper received ※ 17 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO057

Redesign of CERN Linac3 RFQ for Lead 29+

rfq, linac, emittance, cavity

818

S. Benedetti, G. Bellodi, J.-B. Lallement, A.M. Lombardi
CERN, Geneva, Switzerland

CERN Linac3 is at the start of the CERN Heavy Ion Facility, providing 4.2 MeV/u ion beams to the Low Energy Ion Ring (LEIR). It mostly accelerates 208Pb²⁹⁺, though in recent years runs were performed with 40Ar¹¹⁺ and 129Xe²²⁺, in view of the increasing interest of the physics community towards lighter ions experiments. In the framework of the LHC Injectors Upgrade (LIU) project, measurements and beam dynamics simulations showed that a transmission bottleneck of Linac3 is represented by the RFQ. As this accelerator was originally designed for 208Pb²⁵⁺, the lower beam rigidity of the heavy ions currently in use and planned for the future permits a redesign of the RFQ optics aimed at increasing its transverse acceptance, and thus the transmitted beam current. A study of this has been performed, and the methodology adopted and the results are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO057

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paper received ※ 11 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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THPO058

RF Design of a High-frequency RFQ Linac for PIXE Analysis

rfq, linac, cavity, proton

822

H.W. Pommerenke, A. Bilton, A. Grudiev, A.M. Lombardi, S.J. Mathot, E. Montesinos, M.A. Timmins, M. Vretenar
CERN, Geneva, Switzerland
H.W. Pommerenke, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: This work has been sponsored by the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (grant no. 05E12CHA).
Protons with an energy of few MeV are commonly used for Ion Beam Analysis of materials, in particular with the Proton Induced X-ray Emission technique (PIXE). Because of its non-damaging character, PIXE is used in a variety of fields, in particular for the diagnosis of cultural heritage artwork. A compact accelerator based on a high frequency RFQ (Radio Frequency Quadrupole) linac has been designed and is being built at CERN. The length of the RFQ is only one meter and it allows the acceleration of a proton beam up to an energy of 2 MeV. The complete system is conceived to be transportable, allowing PIXE analysis almost anywhere. This paper covers the RF design of the compact RFQ operating at 750 MHz. We present general accelerator parameters and the current state of the RF design, which includes RFQ geometry and coupler design, thermal simulation and first particle tracking results.

Slides THPO058 [2.404 MB]

Poster THPO058 [2.192 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO058

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO060

First RF Measurements of the 325 MHz Ladder RFQ

rfq, linac, proton, coupling

826

M. Schuett, U. Ratzinger, M. Syha
IAP, Frankfurt am Main, Germany

Funding: BMBF 05P15RFRBA
Based on the positive results of the unmodulated 325 MHz Ladder-RFQ prototype from 2013 to 2016, we developed and designed a modulated 3.3 m Ladder-RFQ*. The unmodulated prototype Ladder-RFQ features a very constant voltage along the axis. The RFQ was high power tested at the GSI test stand. It accepted 3 times the RF power level needed in operation**. That level corresponds to a Kilpatrick factor of 3.1 with a pulse length of 200 µs. The 325 MHz RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the proton linac within the FAIR project. This particular high frequency creates difficulties for a 4-ROD type RFQ, which triggered the development of a Ladder RFQ with its higher symmetry. The results of the unmodulated prototype have shown, that the Ladder-RFQ is a suitable candidate for that frequency. For the present design duty cycles are feasible up to 5%. The basic design and tendering of the RFQ has been successfully completed in 2016. Manufacturing will be completed in August 2018. We will show the the finalization of manufacturing as well as first low level RF measurements of the Ladder RFQ.
*Journal of Physics: Conf. Series 874 (2017) 012048
**Proceedings of LINAC2016, East Lansing, TUPLR053

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO060

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO061

Beam Characterization of the MYRRHA-RFQ

rfq, diagnostics, proton, injection

830

P.P. Schneider, M. Droba, O. Meusel, H. Podlech, A. Schempp
IAP, Frankfurt am Main, Germany
D. Noll
CERN, Geneva, Switzerland

Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) #05P15RFRBA and HORIZON 2020 for the MYRRHA project #662186 and HIC for FAIR.
The Linear Accelerator for the MYRRHA project* is under construction. In a first step the linac up to 100 MeV will be realized. The LEBT section has been set into operation in Belgium and the RFQ is installed in summer 2018. A system to analyze the ion beam consisting of a slit-grid emittance scanner, a beam dump and a momentum spectrometer, called diagnostic train descripted in **, will be set on the rails to characterize the beam at the RFQ injection point. The results will be used to adjust the optimal matching for the RFQ. After the measurements downstream the LEBT, the diagnostic train begins its journey along the beam line and at the first station the RFQ is installed. The accelerated beam of the RFQ is then analyzed and optimized. In addition to optimization of transmission the artificial production of beam offsets in the LEBT is of special interest. These will be measured at the injection point to estimate the range of possible offsets. In the following measurements these offsets will be used to study the influence of the offsets on the RFQ performance. Furthermore, the RFQ parameters are varied to see their influence on the beam transport, transmission and beam quality.
* H.Aı̈t Abderrahim et al. "MYRRHA: A multipurpose accelerator driven system for research & development", 2001
** 1st Experiments at the CW-Operated RFQ for Intense Proton Beams, LINAC16

Poster THPO061 [4.610 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO061

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO062

IFMIF/EVEDA RFQ Preliminary Beam Characterization

rfq, MMI, operation, proton

834

E. Fagotti, L. Antoniazzi, L. Bellan, M. Comunian, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo
INFN/LNL, Legnaro (PD), Italy
T. Akagi, K. Kondo, K. Sakamoto, T. Shinya, M. Sugimoto
QST, Aomori, Japan
P. Cara
IFMIF/EVEDA, Rokkasho, Japan
H. Dzitko, I.M. Moya
F4E, Germany
R. Heidinger, A. Marqueta
Fusion for Energy, Garching, Germany
I. Podadera
CIEMAT, Madrid, Spain

The IFMIF/EVEDA RFQ is the longest and powerful operated. Therefore, it requires a careful characterization from several aspects: beam dynamics, RF, mechanics, installation and commissioning. Due to the very large power handling, the preliminary beam operation was decided to be performed with a low proton beam current at one half of the voltage needed for deuteron accelera-tion, i.e. from 8 mA to 30 mA at 2.5 MeV in pulsed mode, with respect to the nominal 130-mA deuteron beam at 5 MeV in CW. In this framework, it will be presented the characterization of the RFQ in terms of simulation and measurements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO062

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO068

AN Effect of Field Emission on Low Beta Superconducting Cavities

pick-up, cavity, SRF, linac

849

X. Liu, Z. Gao, Y. He, G. Huang
IMP/CAS, Lanzhou, People’s Republic of China

Superconducting RF (SRF) technology is widely ap-plied in particle accelerators to shorten the accelerator length and lower the construction price due to its high acceleration gradients with low rf losses. Field emission is the chief limitation associated with the surface electric field which will finally determine the cavity performance during the operation. The pickup-drop signal caused by field emission seriously affect the stable operation of the superconducting linac in the Chinese initiative Accelera-tor-Driven Sub-critical System (CiADS) demon facility. Simulations of the field emission effect and experimental measurements of the pickup-drop signal have been per-formed on the half wavelength resonator (HWR) cavity. And a modified design of the pickup antenna will be discussed to solve the pickup-drop problem.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO068

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paper received ※ 12 September 2018 paper accepted ※ 09 October 2018 issue date ※ 18 January 2019

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THPO076

Multiphysics Design Studies of a Superconducting Quarter-wave Resonator at Peking University

cavity, multipactoring, SRF, accelerating-gradient

863

M. Chen, S. Chen, A.Q. Cheng, W. Cheng, J.K. Hao, S.W. Quan, F. Zhu
PKU, Beijing, People’s Republic of China

Funding: This work is supported by National Basic Research Program (2014CB845504)
A 81.25MHz, geometric β=0.046 quarter-wave resonator has been designed and analysed at Peking University. This paper mainly presents the multi-physics studies of this cavity, include electromagnetic design, mechanical analysis and multipacting simulation, to predict its behaviour under practical operating process. Various transverse vibration modes of inner conductor were found under different fixed conditions and an asymmetric shorting plate was adopted to avoid high possibility of multipacting
"quarter-wave resonator"
"multiphysics"
"multipacting"
"frequency detuning"
"stiffening design"

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO076

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paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO080

Design Validation of a Chopping and Deflecting System for the High Current Injector at IUAC

experiment, vacuum, diagnostics, power-supply

869

S. Kedia, R. Ahuja, R. Kumar, R. Mehta
IUAC, New Delhi, India

A chopping and deflecting system has been designed and developed to provide the chopped beam with various repetition rates at the IUAC experimental facilities. It consists of four pairs of deflecting plates with increasing gap from 15 mm to 21 mm to maximize the effective electric field, preserve the beam emittance and to maximize the transmission efficiency within the same voltage conditions. The design of CDS has been validated with various simulation codes like CST MWS, Solid Works, Python and TRACE 3D. The deflecting plates have been fabricated, and assembled with in the design accuracy of 100 microns. A vacuum chamber has been designed and fabricated to incorporate the deflector plate assembly. The CDS unit has been installed in the Low Energy Ion Beam Facility at the IUAC to validate the design value of ion beam deflection. A slit has been installed to cut the deflected charge particles. Since the pulse power electronics required for chopping is presently under design we have used DC voltage across the four pairs of deflecting plates and amount of deflection was measured accordingly. The design, development, and DC beam test will be discussed in the article.

Poster THPO080 [2.037 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO080

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO082

Physical Design of a Rectangular RF Deflector for Ultrashort Bunch Length Measurement

cavity, electron, FEL, coupling

872

J. Bai, Q.S. Chen, K. Fan
HUST, Wuhan, People’s Republic of China

Cylindrical deflectors which are now widely used for bunch length measurement suffer from the degeneration of polarization, while rectangular deflectors can separate polarization mode easily. This paper is focused on the study of a one-cell rectangular deflector, which is considerably different from cylindrical structure or multi-cell structure. A one-cell structure is free of π mode restriction and can achieve higher deflection efficiency per unit length. The proposed scheme is expected to achieve time resolution better than 200fs with the driving power less than 1MW. Cavity optimization and beam dynamic simulation are introduced in this paper.

Poster THPO082 [0.484 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO082

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO084

BPM Time of Flight Measurements for Setting-up the RF Cavities of the CERN Linac4

linac, cavity, DTL, electron

879

M. Bozzolan
CERN, Geneva, Switzerland

The newly constructed H⁻ LINAC4 at CERN has recently completed its first extended reliability run. It is equipped with Beam Position Monitors (BPMs) based on shorted-stripline pick-up electrodes to measure both position and Time of Flight (ToF). The ToF, in turn used to calculate the kinetic energy of the beam, is determined through signal phase shift measurements between pairs of BPMs. ToF measurements are performed by scanning of the phase of the RF injected into the cavities to find the nominal RF settings for optimal beam acceleration. This paper focuses on the technical aspects of the ToF measurement as well as on the results obtained during beam commissioning and their comparison with beam dynamics simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO084

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paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019

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THPO090

The Analysis of Module Failure in High Solid-state Amplifier for High Current RFQ

scattering, experiment, rfq, cavity

886

L.P. Sun, Y. He, G. Huang, C.X. Li, L. Lu, A. Shi, L.B. Shi, X.B. Xu, H.W. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

New accelerator RF system was upgraded to the solid-state amplifier in ADS project due to its stable, sustainable and reliable. Until now, newest 80kW SSA was adopted in IMP, operating in 162.5MHz, and over 120 power modules were combined through several synthesizers for 80kW output. but since too many modules were optimized for amplitude and phase in the same time, one or some failure of circulator will lead to injure of whole RF system, when wavelength meets a specific condition, injure would turn out severe accident and heavy loss. In this paper, analyzing and simulating the multi-level synthetic matrix was the important method for ADS accident happened in June 20. 2017, the failure simulated results for RF amplify links under the specific circumstances also was presented simultaneously.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO090

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paper received ※ 17 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

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THPO096

Design Study of a High Efficiency Klystron for SuperKEKB Linac

klystron, cavity, gun, linac

901

F. Qiu, S. Fukuda, S. Matsumoto, T. Matsumoto, T. Miura, T. Natsui
KEK, Ibaraki, Japan

The injector linear accelerator (linac) for the SuperKEKB particle accelerator requires a higher efficiency klystron than the currently used 50 MW, S-band, pulsed unit (PV3050/E3730), which operates at the same voltage, to increase the power redundancy. The efficiency is expected to improve from the currently observed 45% to more than 60%. We propose a type of high efficiency klystron using novel bunching mechanisms. The 1-D disk model based code is used for preliminary optimization of the tube parameters; these parameters are further checked by 2-D codes known as field charge interaction (FCI) and MAGIC. In this paper, the design consideration of the high efficiency klystron is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO096

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO100

Development of a 1.5 GHz High-power CW Magnetron for SRF Accelerator

cavity, electron, SRF, coupling

908

L. Wenliang
College of Engineering and Applied Sciences for Nanjing University, Nanjing, People’s Republic of China
S. An, Y.J. Ke, S. Lingbin, Z. Pengjiao, L. Youchun, L. Zhao, B.Z. Zhou
PLAI, Nanjing, People’s Republic of China
J.Z. Li, L.P. Zhang, Hou, R. Rui
ADS, Jiangsu Province, People’s Republic of China

An 1.5 GHz, 13.5 kW CW high-power magnetron for a superconducting RF accelerator has been developed by Andesun Technology Group Co., Ltd. with Nanjing Sanle Electronic Information Industry Group Co., Ltd., in order to replace the klystron, that could reduce the power source cost to about one-third. The cavity, output power antenna and coupling door-nob have been optimized by using CST Studio. Testing results have shown that the resonance frequency and output power have met the requirements, and the efficiency of the magnetron is higher that 78.45%.

Poster THPO100 [0.574 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO100

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO102

Design Studies of Output Window for CEPC Klystron

klystron, multipactoring, electron, operation

911

Z.J. Lu, Y.L. Chi, S. Fukuda, G. Pei, S. Pei, S.C. Wang, O. Xiao, U. N. Zaib, Z.S. Zhou
IHEP, Beijing, People’s Republic of China
S. Fukuda
KEK, Ibaraki, Japan

A high power and high efficiency klystron of the 650MHz, 800kW CW klystron for the Circular Electron Positron Collider (CEPC) is designed and developed at IHEP. This paper presents the design and simulation for the high power coaxial window for it. Plan of the hot test (high power testing before installing to the klystron) are also described. Simulation software of CST, ANSYS and Multipac 2.1 are used for design of window microwave structure, thermal analysis and multipacting effects. We obtained the good simulation results successively; the coaxial window S-parameter analysis, has revealed a low reflection at the operating frequency of 650 MHz. The thermal simulation shows a good temperature distribution under the cw 800kW propagation; maximum temperature has been found to be 33 °C at ceramic with water cooling in the inner and outer conductor. The multipacting at the window is possible source of the failure and it is shown that multipacting has less chance to be happened on the surface of ceramic.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO102

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paper received ※ 12 September 2018 paper accepted ※ 31 October 2018 issue date ※ 18 January 2019

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THPO107

High Power Coupler R&D for Superconducting CH-cavities

cavity, linac, Windows, heavy-ion

920

J. List, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany
W.A. Barth, M. Heilmann, J. Salvatore, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany
M. Basten, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany

The upcoming demands of the future research programs at GSI exceed the technical opportunities of the existing UNIversal Linear ACcelerator (UNILAC). Besides, the machine will be exclusively used as an injector for FAIR (Facility for Antiproton and Ion Research) providing high power heavy ion beams at a low repetition rate for injection into the synchrotron. A new dedicated superconducting (sc) continuous wave (cw) Linac is crucial to keep the research program competitive. The first part of the cw-linac, comprising a 217 MHz multi gap Crossbar-H-mode (CH) cavity surrounded by two sc solenoids inside a cryostat, already served as a prototype demonstrating reliable operability in a realistic accelerator environment. A sufficient high power RF-coupling concept is needed to feed this newly developed cw-RF cavity with up to 5 kW of RF-power. A high power coupler test stand was recently built to provide for a testing environment; further upgrade measures of this test area are foreseen. This contribution deals with the recent coupler R&D for the demonstrator set up. Besides simulations of thermal losses at the coupler (inside the RF-cavity) will be shown as well.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO107

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paper received ※ 12 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019

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THPO109

A New Spherical Pulse Compressor Working with Degenerated "Whispering Gallery" Mode

cavity, coupling, GUI, collider

928

Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People’s Republic of China
A. Grudiev
CERN, Geneva, Switzerland

CLIC is focusing on the Compact Linear Collider. To obtain a relatively high accelerating gradient, CLIC utilizes Pulse Compressors to increase the input power of accelerators. This work is to make an alternative design for CLIC pulse compression scheme. There are several kinds of pulse compressor: SLED, BOC, SLED-Ⅱ, spherical pulse compressor and so on. Usually, a spherical cavity, including BOC, can offer a higher Q factor compared with a cylindrical cavity. This design utilizes a spherical cavity working with degenerated Whispering Gallery mode.

Slides THPO109 [1.738 MB]

Poster THPO109 [1.913 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO109

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paper received ※ 11 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO111

The Test of RF Breakdowns of CPHS RFQ

rfq, pick-up, linac, proton

931

W.B. Ye, C. Cheng, X. Guan, J. Shi, X.W. Wang, Q.Z. Xing, S.X. Zheng
TUB, Beijing, People’s Republic of China
M.C. Wang
NINT, Shannxi, People’s Republic of China

The high accelerating gradient is significant for a compact linear accelerator, and RF breakdowns is a limitation for the high gradient. This work aims to research RF breakdowns of a 325MHz proton Radio Frequency Quadrupole (RFQ) accelerator of the Compact Pulsed Hadron Source（CPHS）. The breakdown rate (BDR) of the RFQ has been measured. Breakdown waveforms have been recorded, which have been used for counting breakdown time distribution and analyzing the location of RF breakdowns.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO111

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paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO113

Design of 4 Ampere S-Band Linac Using Slotted Iris Structure for Hom Damping

linac, HOM, damping, target

934

J. Pang, S. Chen, X. He
CAEP/IFP, Mainyang, Sichuan, People’s Republic of China
S. Pei, H. Shi, J.R. Zhang
IHEP, Beijing, People’s Republic of China

An S-band LINAC with the operating frequency of 2856 MHz and beam current of 4 A was designed for flash X-ray radiography for hydrodynamic test. The optimization of the parameters of the LINAC was processed to obtain the minimum beam radius and the maximum energy efficiency. For the purpose of reducing the beam orbits offset at the exit of LINAC, a slotted iris accelerating structure would be employed to suppress the transverse Higher Order Modes (HOMs) by cutting four radial slots in the iris to couple the HOMs to SiC loads. In this paper, we present the design of the LINAC and the results of beam dynamic analysis.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO113

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paper received ※ 10 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019

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THPO118

Beam Transverse Coupling and 4D Emittance Measurement Simulation Studies for PITZ

emittance, quadrupole, coupling, gun

945

Q.T. Zhao, M. Krasilnikov, H.J. Qian, F. Stephan
DESY Zeuthen, Zeuthen, Germany
Q.T. Zhao
IMP/CAS, Lanzhou, People’s Republic of China

The Photo Injector Test Facility at DESY, Zeuthen site (PITZ) was built to test and optimize high brightness electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. Although the beam emittance has been optimized and experimentally demonstrated to meet the requirements of FLASH and XFEL, transverse beam asymmetries were observed during operation of the RF guns. Based on previous studies [1], the beam asymmetries most probably stem from beam transverse coupling by quadrupole field errors in the gun section. A pair of normal and skew gun quadrupoles was successfully used for reducing the beam asymmetries in experiment. In this paper, we discuss the beam transverse coupling between X and Y planes due to quadrupole field errors and its impact onto horizontal and vertical rms emittance. Multi-quads scan and two quads with rotated slits scan were proposed to measure the 4D beam matrix for PITZ and tested by simulation, which will give the residual beam coupling after gun quadrupoles compensation and would be helpful for minimizing the 2D rms emittance experimentally.

Poster THPO118 [1.521 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO118

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paper received ※ 08 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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THPO132

Study of the Electron Beam Transfer Line for the AWAKE RUN II Experiment at CERN

electron, plasma, experiment, emittance

962

S.Y. Kim, M. Chung
UNIST, Ulsan, Republic of Korea
M. Dayyani
IPM, Tehran, Iran
S. Döbert
CERN, Geneva, Switzerland

Proton Beam-Driven Plasma Wakefield Accelerator (PBD-PWFA) has been actively investigated at CERN within the AWAKE experiments to study the electron beam acceleration using plasma wake fields of the order of GV/m. In the AWAKE RUN 1 experiment an electron beam with an energy of 19 MeV and a bunch length of 2.2 ps rms has been used for the first demonstration of electron beam acceleration in the plasma wake fields. It has been observed that the energy gain of the electron beam is up to 2 GeV, and electron capture efficiency is few percent. Higher capturing efficiency and emittance preservation could be achieved by making the electron beam short enough to be injected only into the acceleration and focusing phase of the plasma wake fields. The electron accelerator needs to be upgraded for AWAKE RUN 2 experiments to obtain a bunch length less than 100 fs which corresponds to a quarter of the plasma wavelength. Planned electron beam parameters for the AWAKE RUN 2 are a beam charge of 100 pC, and a beam energy larger than 50 MeV. In this paper, we show the electron beam parameters for RUN 2, and the parameters of the transfer line such as Twiss parameters, beam envelope, and emittance.
UNIST, Ulsan, 44919, Korea
Institute For Research in Fundamental Sciences, 19395-5531, Tehran, Iran
CERN, Geneva 1211, Switzerland

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO132

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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FR1A01

Results From the 6D Diagnostics Test Bench at SNS

experiment, quadrupole, diagnostics, emittance

966

B.L. Cathey
ORNL RAD, Oak Ridge, Tennessee, USA
A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This work has been partially supported by NSF Accelerator Science grant 1535312.
This paper presents the method and results for measuring the full six-dimensional phase space of a low energy, high intensity hadron beam. This was done by combining four-dimensional emittance measurement techniques along with dispersion measurement and a beam shape monitor to provide the energy and arrival time components. The measurements were performed on the new Beam Test Facility (BTF) at the Spallation Neutron Source (SNS), a 2.5 MeV functional duplicate of the SNS accelerator front end. The results include a correlation the had not previously been observed.

Slides FR1A01 [7.083 MB]

Poster FR1A01 [1.742 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-FR1A01

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paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019

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