Paper | Title | Page |
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SPWR001 |
Evaluation of 60pC Beam Performance at cERL Injector for ERL Based EUV-FEL | |
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In order to compensate for the emittance which is increased by space charge in the low energy region, it is important to transport the beam as designed. Until now, we did not consider couplers in injector superdonducting cavities in optics design. But in this study, to improve optics matching and emittance compensation conditions for space charge dominated beam in cERL at KEK, we introduced a new 3D cavity model. We first investigated the influence of the couplers on electromagnetic field distribution. As a result, it was found that an asymmetric focusing force is generated by the influence of the couplers. It also became clear that the influence of the coupler kick on the optics significantly devastated the emittance compensation condition from the calculating including space charge. Furthermore, it was found that by optimizing the optics in consideration of the coupler kick, it is possible to improve the beam control accuracy and reduce the emittance in beam commissioning. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO009 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR002 |
Coherent Synchrotron Radiation Monitor for Microbunching Instability in XFEL | |
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MOPO040 | use link to access more material from this paper's primary paper code | |
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The microbunching instability is an important issue in an X-ray Free Electron Laser (XFEL). The intensity of the FEL can be reduced significantly by the microbunching instability so that the laser heater is widely used to reduce it. In the X-ray Free Electron Laser of the Pohang Accelerator Laboratory (PAL-XFEL), to directly monitor the microbunching instability, a visible CCD camera was included into the coherent radiation monitor (CRM) which uses a pyroelectric detector. It enabled us to measure the microbunching instability more clearly and optimize the FEL lasing in the PAL-XFEL. | ||
Slides SPWR002 [1.125 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO040 | |
About • | paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR003 |
Evolutionary Many-objective Optimization Algorithm for Large-bandwidth Free-Electron-Laser Generation | |
MOPO042 | use link to access more material from this paper's primary paper code | |
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Funding: National Natural Science Foundation of China , the National Key Research and Development Program of China, the Young Elite Scientist Sponsorship Program by CAST and Ten Thousand Talent Program. X-ray free-electron lasers (XFELs) are leading-edge instruments in a wide range of research fields. Besides pursuing narrow bandwidth FEL pulses, the large-bandwidth XFEL pulses are very useful in various spectroscopy experiments, multi-wavelength anomalous diffraction, and X-ray crystallography. Overcompression operation scheme can be utilized to generate electron beams with large energy chirp which is benefit for bandwidth broadening. Recently, an evolutionary many-objective (having four or more objectives) algorithm, NSGA-III, was used to optimize the electron beam parameters in the overcompression including energy chirp, energy spread, current profile, peak current, and projected emittance. In this paper, combining with the Xie’s semianalytical estimate formula, the NSGA-III is utilized to find an optimal working point of linac by optimizing the XFEL pulse properties directly. Start-to-end numerical simulations based on the Shanghai soft X-ray Free-Electron Laser user facility parameters demonstrate that a full bandwidth of 4.75% can be generated. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO042 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 | |
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SPWR004 |
Study on Generation of Variable Polarized Coherent THz Radiation Using a Crossed Undulator | |
MOPO076 | use link to access more material from this paper's primary paper code | |
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A variable polarized THz radiation source using a crossed undulator system has been developed at Tohoku University. In this scheme, two coherent undulator radiations from an extremely short electron bunch are used to control the polarization. They are linearly polarized radiations orthogonal to each other. Polarization of superimposed radiation is controlled by adjusting a relative phase between them. A compact planar undulator with seven periods has been designed for an experiment at our facility. The radiation frequency is 2.06 THz for electron beam energy of 22 MeV. The opening angle of the crossed undulator radiation was estimated to be 34 mrad (FWHM). Since the polarization state of the crossed undulator depends on observation angle, its angular dependence was evaluated. It was found that ideal polarization control is realized only in the angle range of 2.5 mrad, which is quite smaller than that of the radiation itself. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO076 | |
About • | paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR005 |
L-band Resonant Ring for Testing RF Windows for ILC | |
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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. | ||
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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SPWR006 |
Survey and Alignment System of 100 MeV/100 kW Electron Linear Accelerator | |
MOPO028 | use link to access more material from this paper's primary paper code | |
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For successful operation and working of electron linear accelerator of "NEUTRON SOURCE" driver it is necessary that all the acceleration sections, the quadrupole triplets, the quadrupole lenses, the dipole magnets, the scanning magnets and the chicane should be installed in design position according design parameters. Accuracies of all electromagnetic elements installation are 150 mkm for all three rotation freedom. The whole process, fiducialization and developing of survey net, alignment is controlled by laser tracker Leica AT 401. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO028 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR007 |
Investigation of 2D PBG Waveguides for THz Driven Acceleration | |
THPO016 | use link to access more material from this paper's primary paper code | |
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Funding: Work supported by the STFC PhD Studentship Novel accelerating techniques that overcome the limitations of conventional RF technology are receiving significant interest. Moving from RF to the THz frequency range, higher gradient of acceleration of high energy beams can be achieved in miniaturised structures. Moreover, with respect to the optical frequency range, the THz regime allows for larger structures and better beam quality to be obtained. In this paper, we investigate the use of a 2D photonic bandgap (PBG) waveguide for THz driven electron acceleration. In accelerator applications, the properties of PBG waveguides can be exploited to damp higher order modes and offer low-loss dielectric confinement at high frequency. In particular, 2D PBG waveguides offer a good compromise between manufacturability, total photonic bandgap confinement, and ease of parallel illumination. The structure here proposed is optimised for maximum bandgap and single mode operation. Dispersion characteristics of the accelerating mode are studied to achieve the best compromise between high accelerating field and effective accelerating bandwidth, given a ~10% bandwidth of the THz driving pulse. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO016 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR008 |
Electron Gun for 100 MeV / 100 kW Linear Accelerator of Electrons as the Driver of Nuclear Subcritical Assembly Neutron Source | |
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100 MeV / 100 kW linear electron accelerator of The "neutron source" nuclear subcritical assembly uses the 120 KW triode electron gun as the primary source of electrons. The gun is designed, manufactured and tested at IHEP, Beijing, China. At present, the gun is installed, tested. The maximum impulse current of the gun equal to 2 A. Under design operation, the impulse current of the gun equal to 0.55 A.The report describes the construction of a 120 kV triode electron gun, the results of testing and test operation. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO002 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 | |
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SPWR009 |
Progress of the Novel Three-dimensional Spiral Injection Scheme Test Experiment | |
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Funding: This work was supported by JSPS KAKENHI Grant Number JP26287055 and JP 23740216. A new muon g-2/EDM experiment at J-PARC (E34) is under preparation in order to resolve a 3𝜎 discrepancy of muon anomalous magnetic dipole moment between the measurement and the standard model prediction. The E34 experiment will employ a unique three-dimensional spiral injection scheme in order to store the muon beam into a small storage orbit. In order to demonstrate the feasibility of this novel injection scheme, the Spiral Injection Test Experiment (SITE) with the electron beam is under construction at KEK Tsukuba campus. The goals of the SITE are divided into two phases. In the first phase of the SITE, 80 keV DC electron beam was injected and detected as a fluorescent light due to the de- excitation of the nitrogen gas into solenoidal storage magnet. In the second phase of the SITE, the pulsed electron beam, and a pulsed magnetic kicker are developed in order to keep the pulsed beam on the very midplane of the solenoidal storage magnet. This paper describes the achievements of the first phase of SITE and progress towards the second phase. *H. Iinuma et al., Nuclear Instruments and Methos in Physics Research A, 832, 51-62 (2016). |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO017 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 | |
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SPWR010 |
Cryogenic Tests of the Superconducting β=0.069 CH-cavities for the HELIAC-project | |
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In the future the existing UNILAC (UNIversal Linear Accelerator) at GSI will be most exclusively used as an injector for FAIR to provide short pulse high intensity heavy ion beams at low repetition rates [Barth3]. A new superconducting (sc) continuous wave (cw) high intensity heavy ion Linac should provide ion beams with max. duty factor above the coulomb barrier for the Super Heavy Element (SHE) program at GSI. The fundamental Linac design comprises a low energy beam transport (LEBT)-section followed by a sc Drift Tube Linac (DTL) consisting of sc Crossbar-H-mode (CH) structures for acceleration up to 7.3 MeV/u [*]. After the successful test and commissioning of the first demonstrator section with heavy ion beam from the HLI in 2017 [**], the next two sc CH-structures have been constructed and the first one has been extensively tested at cryogenic temperatures at the Institute for Applied Physics (IAP) at Goethe University Frankfurt (GUF). The results of the final cold test of the first CH-structure as well as the next steps realizing a new sc cw heavy ion LINAC at GSI will be presented.
[*]W. Barth et al., "Further investigations for a superconducting cw-Linac at GSI" [**]W. Barth et al., "First high intensity heavy ion beam tests with a superconducting multi gap CH-cavity" |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO072 | |
About • | paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR011 |
AN Effect of Field Emission on Low Beta Superconducting Cavities | |
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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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SPWR012 |
Cold Test of Hybrid RFQ Prototype | |
MOPO087 | use link to access more material from this paper's primary paper code | |
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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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SPWR013 |
High Frequency RFQ Design and LEBT Matching for the CERN TwinEBIS Ion Source | |
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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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SPWR014 |
Error Study of CPHS DTL after Assembly | |
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The Compact Pulsed Hadron Source (CPHS) at Tsinghua University is one multi-purpose pulsed neutron source. The injector of the CPHS is a linac, which mainly consists of a source, a low-energy beam transport line (LEBT), a radio frequency quadrupole (RFQ) and a drift tube linac (DTL). The error study of the DTL for CPHS is presented in this paper. The error study can provide the field tolerances in the DTL cavity and the alignment tolerance between the RFQ and DTL. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO036 | |
About • | paper received ※ 06 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR015 |
Muon Acceleration Test with the RFQ Towards the Development of the Muon Linac | |
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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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SPWR016 |
RF Design of a High-frequency RFQ Linac for PIXE Analysis | |
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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. |
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Slides SPWR016 [2.404 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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SPWR017 |
Beam Characterization of the MYRRHA-RFQ | |
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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 |
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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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SPWR018 |
Fundamental Studies of Impurity Doping in 1.3 GHz and Higher Frequency SRF Cavities | |
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TUPO054 | use link to access more material from this paper's primary paper code | |
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As the demand for more powerful, more efficient, and smaller superconducting RF accelerators continues to increase, both impurity doping and high-frequency cavities (> 1.3 GHz) have become hot topics for fundamental research because of their potential to significantly decrease surface losses and cost respectively. In this report, we present recent experimental and theoretical results on undoped and nitrogen-doped high-frequency cavities and on alternative doping agents in traditional 1.3 GHz cavities, with a focus on understanding the fundamental science of impurity doping. | ||
Slides SPWR018 [1.956 MB] | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO054 | |
About • | paper received ※ 16 September 2018 paper accepted ※ 19 September 2018 issue date ※ 18 January 2019 | |
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SPWR019 |
Improvement of Cavity Performance by Nitrogen Doping at KEK | |
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Nitrogen doping experiments in single-cell and 3-cell niobium cavities were carried out at KEK. After annealing at 800 deg C for 3 hours, pure nitrogen gas with a pressure of 3 Pa for 20 minutes and 3 minutes were introduced for doping in a furnace in J-PARC, respectively. Removing surface in 5 um and 20 um by electropolishing were performed prior to the vertical tests, respectively. Increases of a quality factor at 2K and reduction of the BCS resistance with respect to an accelerating gradient were observed in both cavities. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO065 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 | |
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SPWR021 |
Study Progress of Pulse Laser Annealing for Niobium Film on Copper | |
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Funding: Work supported by Major Research Plan of National Natural Science Foundation of China (No. 91026001). The recent studies of laser annealing on niobium films on copper are reported. Annealing is normally used to deal with the surface, reducing defects and even chang-ing the microstructure of the coating film. Short pulse laser can produce a sharp step temperature field on the film thickness scale (μm), which anneals the surface without substrate heated. The laser annealing experi-ments of niobium thin film sample have been carried out, and according to SEM and FIB results, Nb films melted and recrystallization occurred. Grains growing up can be observed while the power density of laser pulse in-creased. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO048 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 | |
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SPWR022 |
Optimization of Dual Axis Asymmetric Cavity for Energy Recovery Linac | |
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Funding: The reported study was funded by RFBR according to the research project № 18-302-00990 Optimization of the dual axis asymmetric cavity was performed to minimize the ratio of the peak magnetic and electric fields values to the accelerating voltage, to increase the distance between operating and neighbouring modes as well as to reduce the manufacturing cost of the cavity. To reach the goals several solutions have been suggested bringing the ratios to the acceptable values and leading to simplification of the manufacturing of the structure. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO045 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR023 |
A New Spherical Pulse Compressor Working with Degenerated "Whispering Gallery" Mode | |
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THPO109 | use link to access more material from this paper's primary paper code | |
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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 SPWR023 [1.738 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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SPWR025 |
High Power Coupler R&D for Superconducting CH-cavities | |
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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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SPWR026 |
LLRF R&D Towards CW Operation of the European XFEL | |
MOPO104 | use link to access more material from this paper's primary paper code | |
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The ever growing request for machines with a higher average beam pulse rate and also with a relaxed (< 1 MHz) pulse separation calls for superconducting linacs that operate in Long Pulse (LP) or Continuous Wave (CW) mode. For this purpose the European X-ray Free Electron Laser (European XFEL) could be upgraded to add the ability to run in CW/LP mode. Cryo Module Test Bench (CMTB) is a facility used to perform tests on superconducting cavity cryomodules. Because of the interest in upgrading European XFEL to a CW machine, CMTB is now used to perform studies on XM-3, a 1.3 GHz European XFEL-like cryomodule with modified coupling that is able to run with very high quality factor (QL = 10E7…10E8) values. The RF power source allows running the cavities at gradients larger than 16 MV/m. Because of the QL and gradient values involved in these tests, detuning effects like mechanical resonances and microphonics became more challenging to regulate. The goal is then to determine the appropriate set of parameters for the LLRF control system to keep the error to be less than 0.01° in phase and 0.01% in amplitude. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO104 | |
About • | paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR027 |
Performance Evaluation of the RF Reference Phase Stabilization System on Fiber-optical Link for KEK e−/e+ Injector LINAC | |
MOPO107 | use link to access more material from this paper's primary paper code | |
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KEK e−/e+ injector is the 600 m J-shaped LINAC which has 8 RF sectors. Stabilization of RF phase reference for long distance transmission is necessary for stable RF operation. In the present system, single-mode fiber-optical links without feedback control are used from sector 2 to 5. For the SuperKEKB, the phase stability requirement is within 0.1 deg. rms. The more stable RF phase reference is necessary to improve the phase stability. In this paper, a feedback control system for RF reference phase stabilization is tested for system performance evaluation. The temperature and humidity characteristics of the electric and optical components and phase stabilized optical fiber (PSOF) with different wavelengths will also be presented. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO107 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 | |
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SPWR028 |
Physical Design of a Rectangular RF Deflector for Ultrashort Bunch Length Measurement | |
THPO082 | use link to access more material from this paper's primary paper code | |
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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. | ||
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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SPWR029 |
Optimized Design for a Compact Linac with Collinear Absorbing Loads at the Hust FEL-THz | |
MOPO118 | use link to access more material from this paper's primary paper code | |
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To meet the requirement of miniaturization for high power THz radiation in the field of commercial and civil use, RF Linacs have been applied widely as beam injectors, and the Linac with collinear absorbing loads reveals the potential to achieve a tradeoff between performance and compactness. Under overall consideration of systematic conflicts, optimization choices for such Linacs involving power absorbing ability, accelerating efficiency, as well as beamline length were described in this context. Meanwhile, cold testing has been conducted to verify design parameters for the collinear absorbing loads. Furthermore, elaborated calculation of thermal power loss and integrated helical water channel cooling has been performed for the 14MeV Linac with collinear absorbing loads installed on the HUST FEL-THz, and online experiments demonstrated that both the accelerating efficiency and the water cooling performance fulfilled operation demands. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO118 | |
About • | paper received ※ 11 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR030 |
Excitation of Millimeter Wavelength Cavity Structure | |
TUPO093 | use link to access more material from this paper's primary paper code | |
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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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SPWR031 |
Particle Dynamics Optimization in DTL | |
TUPO116 | use link to access more material from this paper's primary paper code | |
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The research concerns ion dynamics in linear accelerators with drift tubes (DTL). Permanent quadrupole magnets are placed inside some of the drift tubes. Frequency of the field is 432 MHz. Electromagnetic fields and particle dynamics in the cavity are calculated using Comsol Multiphysics software. The input energy of the beam is 6 MeV, output 10 MeV. Initial beam is assumed to come from Radio Frequency Quadrupole accelerator (RFQ). The considered parameters are drift tubes radii, cavity diameter, gradient of the magnetic field from quadrupoles inside drift tubes and focusing lattice. Effectiveness is estimated by the emittance growth. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO116 | |
About • | paper received ※ 14 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR032 |
Calculation of Electron Beam Dynamics in Four Accelerating Stations for JINR Linear Electron Accelerator LINAC-200 | |
TUPO112 | use link to access more material from this paper's primary paper code | |
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In the Joint Institute for Nuclear Research a Test Stand with an electron beam generated by the linear accelerator LINAC-200 with the energy up to 200 MeV is being constructed to investigate properties of accelerating and semiconducting structures for advanced detectors, a radiation resistance of detectors based on gallium arsenide semiconductor, to study a free electron laser and to do other applied for work. The technical characteristics of the LINAC-200 accelerator make it possible to create an advanced system of test beams for scientific and methodological studies of detectors on its basis. Four accelerating stations with maximum beam energy up to 200 MeV are put into operation. The work is being carried out for experiments with electron test beams with energy up to 800 MeV. This work presents the calculation results of the magnetic field of the focusing solenoidal system and electron beam dynamics in accelerating stations. In addition, the results on the formation of the electron beam with optimal parameters to be captured in further accelerating sections. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO112 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 08 October 2018 issue date ※ 18 January 2019 | |
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SPWR033 |
Beam Dynamics for the FAIR p-Linac Ladder RFQ | |
TUPO083 | use link to access more material from this paper's primary paper code | |
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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. | ||
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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SPWR034 |
Beam Dynamics Simulations for the New Superconducting CW Heavy Ion LINAC at GSI | |
TUPO084 | use link to access more material from this paper's primary paper code | |
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Funding: Work supported by BMBF contr. No. 05P15RFRBA, EU Framework Programme H2020 662186 (MYRTE) and HIC for FAIR For future experiments with heavy ions near the coulomb barrier within the super-heavy element (SHE) research project a multi-stage R&D program of GSI/HIM and IAP is currently in progress. It aims for developing a supercon-ducting (sc) continuous wave (CW) LINAC with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The LINAC design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with unchanged minimum energy spread. Testing of the first CH-cavity in 2016 demonstrated a promising maximum accelerating gradient of Ea = 9.6 MV/m; the worldwide first beam test with this sc multi-gap CH-cavity in 2017 was a milestone in the R&D work of GSI/HIM and IAP. In the light of experience gained in this research so far, the beam dynamics layout for the entire LINAC has recently been updated and optimized. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO084 | |
About • | paper received ※ 12 September 2018 paper accepted ※ 20 September 2018 issue date ※ 18 January 2019 | |
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SPWR036 |
Study of the Electron Beam Transfer Line for the AWAKE RUN II Experiment at CERN | |
THPO132 | use link to access more material from this paper's primary paper code | |
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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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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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SPWR037 |
Compact H+ ECR Ion Source with Pulse Gas Valve | |
THPO126 | use link to access more material from this paper's primary paper code | |
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We are developing a compact ECR H+ ion source with pulse gas valve. In the case of high current ion linac, the distance between the ion source and the first accelerating tube such as RFQ must be as short as possible to reduce the space charge effect, while operating in a high electric field a good vacuum condition is desirable. Since hydrogen gas always flows out from ion sources if the plasma chamber is filled with the gas, vacuum pumping systems have to evacuate the gas enough before the first accelerating tube. The pulse gas injection system achieved by a fast piezo gas valve can reduce the gas load on the vacuum evacuation system and is suitable for installing the ion source close to the RFQ. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO126 | |
About • | paper received ※ 19 September 2018 paper accepted ※ 21 September 2018 issue date ※ 18 January 2019 | |
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