IPAC2015 - List of Keywords (network)

Paper	Title	Other Keywords	Page
MOBD3	Development of a 9 MHz 15 kW Solid-state CW Amplifier for RHIC	impedance, cavity, resonance, feedback	67
	S.C. Dillon Tomco Technologies, Stepney, South Australia, Australia
	This paper describes the technical details of the development of a high-power solid-state amplifier for Brookhaven Laboratory. The amplifier must withstand short duration events of 100% full-power reflection, and also must guarantee delivery of continuous power into any load impedance at any angle.
	Slides MOBD3 [10.800 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBD3
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MOPJE070	Reduction of Electron Cloud in Particle Accelerator Beampipes Studied by RF Multipacting	electron, injection, vacuum, detector	472
	R. Leber, F. Caspers, P. Costa Pinto, M. Taborelli CERN, Geneva, Switzerland
	For a given beam structure, chamber geometry and magnetic field configuration, the electron cloud (EC) intensity depends on the Secondary Electron Yield (SEY) of the beam pipe. The reduction of the EC density as a function of machine operation time (scrubbing) is attributed to the growth of a low SEY carbon film induced by electron bombardment. In this paper, we study the time evolution of the conditioning of stainless steel beam pipes in a laboratory setup. The EC or multipacting is induced by Radio-Frequency (RF) fields in a coaxial resonator under vacuum. Strip detectors are used to monitor the current of the EC. Induced pressure rise is simultaneously detected. The multipacting intensity shows a linear dependence on the positive DC bias voltage up to 1000 V, applied to the central electrode. An accelerated conditioning is observed for the applied bias voltage. The SEY of samples exposed to the EC is measured and the surface composition is monitored by X-ray Photoelectron Spectroscopy. The measured SEY, surface composition and multipacting behaviour are well correlated. The injection of acetylene and dodecane during multipacting proved to be ineffective in the conditioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE070
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MOPMA004	Numerical Optimization of Accelerators within oPAC	simulation, lattice, controls, quadrupole	533
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485. Powerful simulation tools are required for every accelerator and light source to study the motion of charged particles through electromagnetic fields during the accelerator design process, to optimize the performance of machine diagnostics and to assess beam stability and non-linear effects. The Optimization of Particle Accelerators (oPAC) Project is funded by the EU within the 7th Framework Programme and currently supports 23 Fellows that are based at institutions across Europe. This large network carries out R&D that closely links beam physics studies with the development of diagnostics and beyond state-of-the-art simulation tools. This contribution presents selected research outcomes from oPAC, including the numerical optimization of beam loss monitor locations along the European Spallation Source’s 5 MW proton linac, results from tracking studies for the LHeC lattice that allow beam stability to be assessed, and multi-objective optimization of the linear and non-linear beam dynamics of the synchrotron SOLEIL. In addition, an overview of recent and future oPAC events is also given.
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MOPTY001	Development of Wideband BPM for Precise Measurement of Internal Bunch Motion	impedance, coupling, feedback, synchrotron	937
	K.G. Nakamura Kyoto University, Kyoto, Japan Y.H. Chin, T. Koseki, T. Obina, M. Okada, M. Tobiyama, T. Toyama KEK, Ibaraki, Japan Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Funding: This work was supported by MEXT KAKENHI Grant Number 25105002, Grant-in-Aid for Scientific Research on Innovative Areas titled “ Unification and　Development of the Neutrino Science Frontier” To suppress intra-bunch oscillations and to reduce particle losses, the intra-bunch feedback (IBFB) system has been developed in 2014 for the J-PARC Main Ring (MR). A new BPM was also installed to the MR for the IBFB system. This BPM has a sufficient frequency response and position sensitivity(up to 1.5GHz within 15% fluctuation ). However, a better performance may be needed in future for more precise analysis of internal motions (e.g. due to an electron cloud). We report the development of the BPM and precise measurement results of the BPM characteristics. We also report simulation studies of the digital equalizer which helps to reconstructs the beam shape from beam signals.
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MOPTY063	The Flexible Customized Supervisor and Control System for Utility in TPS	controls, operation, monitoring, vacuum	1085
	C.S. Chen, W.S. Chan, J.-C. Chang, Y.C. Chang, Y.-C. Chung, C.W. Hsu, C.Y. Liu, Z.-D. Tsai NSRRC, Hsinchu, Taiwan
	In order to maintain and operate a synchrotron radiation light source well requires quite a few efforts. All parts of the big machine, including vacuum system, all kinds of magnets, RF facility, cryogenic equipments, radiation security, optic devices and utility equipment must cooperate in harmony to provide high quality light. Any one of the above system contains lots of analog or digital signal transmission, not to mention the vast range of utility. Numbers of programmable automation controllers (PACs) are applied in utility system in TPS to ensure the utility operates normally. In addition to the high reliability and distribution, the flexible programmability of PAC is the most critical feature in this project. A well-designed program, Archive Viewer, provides a platform for showing these big data from all distributed systems. The architecture of the server system for utility is described in this paper as well.
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MOPTY065	Beam Stability of the Taiwan Light Source Storage Ring	betatron, storage-ring, electron, injection	1091
	H.C. Chen, H.H. Chen, Y.-S. Cheng, S.J. Huang, C.H. Kuo, J.A. Li, Y.K. Lin NSRRC, Hsinchu, Taiwan
	The Taiwan Light Source Storage Ring (SR) has been in operation since many years ago. Maintaining best stability of the electron beam is becoming the main challenge. This study endeavored to improve the electron beam stability of The Taiwan Light Source Storage Ring (SR). Employing the artificial neural network (ANN)-constructed experiment design to analyze and optimize the storage ring betatron tunes .This report outlines the details of the beam stability process experiment.
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MOPTY070	Online RadFET Reader for Beam Loss Monitoring System	EPICS, controls, interface, radiation	1097
	C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu NSRRC, Hsinchu, Taiwan
	To investigate the beam loss and its distribution during operation of synchrotron light sources at NSSRC, a sixteen-channel readout box is designed and implemented to read the threshold voltage of the RadFETs installed at accelerator tunnel. To simplify the design, the reader plays a role of remote I/O for EPICS IOC. The IOC collects voltage from readers distributed in the accelerator to deduce the integrated dose and dose rate. User interface is shown in the control console for real-time display and the archived data are processed off-line.
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MOPWI028	Initial Experimental Results of a Machine Learning-Based Temperature Control System for an RF Gun	controls, gun, cavity, monitoring	1217
	A.L. Edelen, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA B.E. Chase, D.J. Crawford, N. Eddy, D.R. Edstrom, E.R. Harms, J. Ruan, J.K. Santucci, P. Stabile Fermilab, Batavia, Illinois, USA
	Colorado State University (CSU) and Fermi National Accelerator Laboratory (Fermilab) have been developing a control system to regulate the resonant frequency of an RF electron gun. As part of this effort, we present experimental results for a benchmark temperature controller that combines a machine learning-based model and a predictive control algorithm for improved settling time, overshoot, and disturbance rejection relative to conventional techniques. Such improvements have implications for machine up-time and management of reflected power. This work is part of an on-going effort to develop adaptive, machine learning-based tools specifically to address control challenges found in particle accelerator systems.
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MOPWI049	Open XAL Services Architecture	interface, framework, software, Linux	1267
	T.A. Pelaia II ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725 Open XAL is an accelerator physics software platform developed in collaboration among several facilities around the world. It includes a powerful new services extension that allows for natural remote procedure calls. The high level services interface is based upon custom implementations of modern standard protocols such as JSON-RPC and WebSockets. This choice of modern protocols allows for flexibility such as seamless communication with web clients free of plugins plus rich object type support. The JSON parser was designed for convenient data type transformations with easy extensibility, high performance and low memory overhead. The Open XAL services architecture features a simple application programming interface, high performance, memory efficiency and thread safety.
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TUAC3	Optimization of Beam Loss Monitor Network for Fault Modes	cavity, detector, simulation, lattice	1356
	Z. Liu, Z.Q. He, S.M. Lidia, D. Liu, Q. Zhao FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 Beam Loss Monitoring (BLM) System is an essential part to protect accelerator from machine faults. Compared with the empirical or uniform BLM arrangement in most accelerators, our new optimization approach proposes a “minimum spatial distribution” for BLM network. In this distribution, BLMs shall be placed at a small set of “critical positions” that can detect all failure / FPS trigger-able events of each fault mode. In additional, to implement a more advanced function of fault diagnosis, BLM should also be placed at “discrimination points” for fault-induced loss pattern recognition. With examples of FRIB failure event simulations, the author demonstrates the proof of concept to locate these “critical positions” and “discrimination points” for the minimum spatial distribution of BLMs.
	Slides TUAC3 [2.341 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAC3
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WEPWA015	RF Input Coupler for 20 K Cooled C-band 2.6-cell Photocathode RF Gun	cavity, simulation, gun, resonance	2522
	T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai LEBRA, Funabashi, Japan M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan T.S. Shintomi Nihon University, Tokyo, Japan
	Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT). For future use in a compact linac-driven X-ray source, a cryo-cooled C-band photocathode RF gun is under development. The RF experiment on the basic 2.6-cell test cavity has shown that the unloaded Q-value of the cavity at 20 K can be explained by the surface resistance based on the anomalous skin effect. Since the cavity was intended for preliminary experiments of the low temperature RF properties, a new test cavity with an RF input coupler has been designed. The basic structure of the accelerating cells has not been changed from the previous cavity. Avoiding an element with a low cooling efficiency such as the inner electrode in a coaxial coupler, a simpler cylindrical input coupler has been designed. The coupler consists of a cylindrical TM01 mode waveguide and a mode converter from a rectangular TE10 mode, with both elements placed on the accelerating axis. The structure and the dimensions of the coupler have been determined using the 3-D simulation code CST Studio so that the resonant frequency of the whole system and the coupling coefficient of the coupler meet the specifications of the RF gun. The new test cavity will be completed early in 2015 at KEK. T. Tanaka et al., Proceedings of IPAC2014, 658-660, http://accelconf.web.cern.ch/AccelConf /IPAC2014/papers/mopri030.pdf
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WEPMA047	MHI's Production Activities of Accelerator Components	status, coupling, LLRF, vacuum	2873
	N. Shigeoka, S. Miura MHI, Hiroshima, Japan
	Mitsubishi Heavy Industries (MHI) is manufacturing various types of accelerator components. Recent production activities, mainly in a field of a normal conducting RF, will be reported in this presentation.
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WEPMN004	Progress on the CSNS Power Supply System	power-supply, controls, dipole, proton	2921
	X. Qi, H. Geng IHEP, Beijing, People's Republic of China
	The 1.6 GeV proton synchrotron proposed in the CSNS Project is a 25 Hz rapid-cycling synchrotron (RCS) with injection energy of 80 MeV. Beam power is aimed to 100 kW at 1.6 GeV. The power supply system consists of seven subsystems. Those power supplies have three operation modes: DC mode, AC plus DC mode and programmable pulse mode. This paper will introduce the Power supply system status in recent years. Power Supply, rapid-cycling synchrotron, serial resonant network
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WEPMN026	Development of Non-resonant Perturbing Method for Tuning Traveling Wave Deflecting Structures	simulation, cavity, higher-order-mode, dipole	2985
	J.H. Tan, W. Fang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China D.C. Tong TUB, Beijing, People's Republic of China
	For traveling wave accelerating structures, the tuning method assisted by bead pull technique based on non-resonant perturbation field distribution measurement has been widely used. Long periodic traveling wave deflecting structure, which operating at HEM11 mode, is difficult to use non-resonant perturbation method, and a improved method has been developed for measuring and tuning by "cage" type perturbing object at SINAP. The measurements on x-band traveling wave deflecting structure are presented in this paper.
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WEPMN052	A New RF Laboratory for Developing Accelerator Cavities at the University of Huelva	cavity, ion, heavy-ion, rfq	3046
	I. Martel, C. Bonțoiu, J.A. Dueñas, D. Gordo-Yáñez, A.K. Orduz, J. Sanchez-Segovia University of Huelva, Huelva, Spain
	The University of Huelva is presently involved in R&D projects for developing RF accelerator cavities. Two types of cavities are presently under design, a prototype of room temperature RFQ injector and a quarter-wave resonator for high intensity heavy-ion linear accelerators. The laboratory is equipped with dedicated test-bench for RF measurements, which includes high-power RF generators, network analyzer, amplifiers and power meters. A clean room is also available having a dedicated space for high-precision mechanical metrology and cavity mounting, together with a vertical cryostat for superconducting cavity test.
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WEPMN070	Measurement Techniques and Application of Combined Parallel/Orthogonal Magnetic Bias on a Ferrite Tuned Resonator in Low Frequency Range (3-10 MHz)	impedance, cavity, solenoid, power-supply	3087
	G. Favia, F. Caspers, M. Morvillo, C. Rossi, C. Vollinger CERN, Geneva, Switzerland
	We present several measurement methods for evaluation of magnetic properties of magnetically biased and non-biased ferrite samples in a coaxial test fixture. One important aspect is the crosscheck of results obtained by using different and independent measurement and evaluation methods. Since a rather high DC bias current has to be applied, a dedicated network was designed that allows the passage of up to 50 A DC without degradation of the RF performance. With a combination of calibration methods and a compensating topology with two identical sample holders, a good performance was achieved. In this context, magnetic material parameters for about 10 different types of ferrite were obtained. The orthogonal magnetic bias was added by placing the entire test fixture into a large toroidal coil. Thus, the bias field can be supplied independently from, and in addition to the classical parallel bias. An optimal combination between the two biasing fields was found, resulting in a reduction of magnetic losses up to 50% on certain ferrites. We show that the mixed magnetization, normally used for garnets only, is beneficial also for other types of ferrites.
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WEPHA002	Electromagnetic Characterization of NEG Properties Above 200 GHz for the CLIC Damping Rings	simulation, impedance, damping, electron	3097
	E. Koukovini-Platia, G. Iadarola, G. Rumolo, C. Zannini CERN, Geneva, Switzerland
	Non-Evaporable Getter (NEG) will be used in the CLIC electron damping rings (EDR) to suppress fast beam ion instabilities due to its effective pumping ability. The electromagnetic (EM) characterization of the NEG properties up to high frequencies is required for the correct impedance modeling of the DR components. The properties are determined using WR-3.4 and WR-1.5 rectangular waveguides, based on a combination of experimental measurements of the complex transmission coefficient S21 with a Vector Network Analyzer (VNA) and CST 3D EM simulations, for the frequency range of 220-330 GHz and 500-750 GHz. The results obtained using NEG-coated Aluminum (Al) waveguides are presented in this paper.
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WEPHA025	Design of a Variable X-band RF Power Splitter	impedance, polarization, operation, scattering	3167
	H. Zha, A. Grudiev, D. Gudkov, I. Syratchev CERN, Geneva, Switzerland
	The design of a two output ports, high power X-Band RF splitter with arbitrary split ratio is presented. This ratio is adjusted by mechanical changing the position a special RF short circuit piston. The piston is mounted on a step-motor providing the precise movement. Special measures were taken in the design to decrease the maximum electrical field on the cooper surface, as well as to maximise the bandwidth of the device. This splitter will be tested in the high power X-band test stand at CERN.
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WEPHA030	EMI Measurement for TPS Booster Kicker and Septum Systems	septum, kicker, booster, injection	3179
	Y.-H. Liu, W.S. Chan, C.S. Chen, J.-R. Chen NSRRC, Hsinchu, Taiwan
	The purpose of this paper is to estimate the conducted and radiated Electromagnetic Interference (EMI) for subsystems in the TPS booster ring. A LISN (Line Impedance Stabilizing Network) system with a wide frequency range was conducted to measure the EMI spectrum of pulsed magnet system. The radiated EMI was tested by magnetic field probe, which the measurement frequency range is 100 kHz ~ 3 GHz. A stray current was tested by wide frequency current transformer in order to measure the conducted current for kicker and septum systems. According to the experiment results, the stray current could flow through the other subsystems or booster chamber, and it might be affected the stability of booster operation. Therefore reducing and eliminating the interference of EM waves will be a very important issue. The EMI prevention scheme will be continued.
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WEPHA044	Alignment Design and Status of Taiwan Photon Source	survey, alignment, storage-ring, booster	3212
	W.Y. Lai, M.L. Chen, P.S.D. Chuang, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, C.J. Lin, S.Y. Perng, T.C. Tseng, H.S. Wang NSRRC, Hsinchu, Taiwan
	After the construction of Taiwan Photon Source (TPS) was finished, the variation of the survey fiducials was stable. However, the following precise alignment work is concerned by the change of temperature critically. In this paper, the whole process of alignment work in the TPS storage ring with the relation of survey network and thermal issues of the environment will be described. We analysed these survey data so that the correction of survey network could be estimated by the change of temperature, thus all the elements for example, booster, pedestals, and girders could be positioned within the shortest time.
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WEPHA053	Surface Resistance RF Measurements of Materials Used for Accelerator Vacuum Chambers	cavity, coupling, factory, resonance	3235
	P. Goudket, L. Gurran, O.B. Malyshev, M.D. Roper, R. Valizadeh, S. Wilde STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt, L. Gurran Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P. Goudket, O.B. Malyshev, R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom S. Wilde Loughborough University, Loughborough, Leicestershire, United Kingdom
	The RF surface resistance of accelerator vacuum chamber walls can have a significant impact on the beam quality. There is a need to know how the use of a new material, surface coating or surface treatment can affect the RF surface resistance. ASTeC and Lancaster University have designed and built two test cavities where one face can be replaced with a sample in the form of a flat plate. The measurements are performed with a network analyser at the resonant frequency of approximately 7.8 GHz.
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WEPHA057	High Gradient Testing of an X-band Crab Cavity at XBox2	cavity, wakefield, klystron, electron	3242
	B.J. Woolley, P.K. Ambattu, R. Apsimon, G. Burt, A.C. Dexter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A. Grudiev, I. Syratchev, R. Wegner, B.J. Woolley, W. Wuensch CERN, Geneva, Switzerland
	CERN’s Compact linear collider (CLIC) will require crab cavities to align the bunches to provide effective head-on collisions. An X-band quasi-TM11 deflecting cavity has been designed and manufactured for testing at CERN’s Xbox-2 high power standalone test stand. The cavity is currently under test and has reached an input power level in excess of 40MW, with a measured breakdown rate of better than 10^-5 breakdowns per pulse. This paper also describes surface field quantities which are important in assessing the expected BDR when designing high gradient structures.
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WEPTY002	Studies into Electron Beam Generation, Acceleration and Diagnostics within LA³NET	laser, acceleration, electron, diagnostics	3256
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	The Laser Applications at Accelerators Network (LA³NET) is receiving funding of up to 4.6 M€ from the European Union within the 7th Framework Programme to carry out R&D into laser-based particle sources, laser acceleration schemes and laser-based beam diagnostics. This international network joins universities, research centres and private companies and has been training 19 early stage researchers at network nodes across Europe since 2011. This contribution presents research outcomes from LA³NET’s main work packages, covering electron beam generation, acceleration and diagnostics. Results from surface studies of photocathodes for photo injector applications in the framework of the CLIC project are presented along with information about expected accelerating gradients in dielectric laser-driven accelerators as identified for non-relativistic and relativistic electron beams using the CST and VSIM simulation codes. Initial results from energy measurements using Compton backscattering at the ANKA Synchrotron at KIT are also presented. In addition, a summary of recent and upcoming international events organized by the LA³NET consortium is also given. This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191.
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WEPTY011	Power Supply Conceptual Design and R&D for the APS Upgrade	power-supply, interface, controls, FPGA	3276
	J. Wang, B. Deriy, T. Fors, R.T. Keane, B. Song 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 MBA upgrade for the APS requires a large number of power supplies with either unipolar or bipolar DC output currents. The unipolar power supplies will be used to power the main coils in the dipole, quadrupole, and sextupole magnets and the bipolar power supplies will be used for the trim or correction coils. There are several demanding requirements of the power supplies. The unipolar power supplies are expected to have a current stability within 10 parts per million (ppm) of the full scale. The currents must be calibrated to the specification and confirmed with independent and accurate measurement. The bipolar power supplies for the fast correction magnets are required to have a wide output current bandwidth in order to minimize the impact on the real-time feedback system for the beam position correction. There are also new requirements for the power supply controls and communications that are much more demanding than that in the existing APS accelerators. This paper will report the conceptual designs of the power supply systems and the R&D program that is developed to find solutions to the technical challenges.
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WEPTY043	Short Pulse Marx Modulator	high-voltage, controls, flattop, collider	3370
	R.A. Phillips, M.P.J. Gaudreau, M.K. Kempkes, B.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA J.A. Casey Rockfield Research Inc., Las Vegas, Nevada, USA
	Funding: DE-SC0004251 High energy, short-pulse modulators are being re-examined for the Compact Linear Collider (CLIC) and numerous X-Band accelerator designs. At the very high voltages required for these systems, all of the existing designs are based on pulse transformers, which significantly limit their performance and efficiency. There is not a fully optimized, transformer-less modulator design capable of meeting the demanding requirements of very high voltage pulses at short pulse widths. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) has completed development of a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort were modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies.
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WEPTY046	Progress on the MICE 201 MHz Cavities at LBNL	cavity, Windows, coupling, simulation	3378
	T.H. Luo, A.J. DeMello, A.R. Lambert, D. Li, S. Prestemon, S.P. Virostek LBNL, Berkeley, California, USA
	The international Muon Ionization Cooling Experiment aims to demonstrate the transverse cooling of amuon beam by ionization in energy absorbers. The final MICE cooling channel configuration has two RF modules, each housing a 201 MHz RF cavity used to compensate the longitudinal energy loss in the absorbers. The LBNL team has designed and fabricated all MICE RF cavities. The cavities will be post-processed and RF measured before being installed in the RF modules. We present the recent progress on this work, including the low level RF measurement on cavity body and Be windows, the electro-polishing (EP) on the cavity surface, the numerical simulation on cavity Be window detuning, and the ongoing mechanical designing work of cavity components.
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WEPTY057	Adaptable Machine Protection Architecture for CW, High Intensity Accelerators	database, operation, framework, real-time	3402
	S. Assadi Texas A&M University, College Station, Texas, USA
	Funding: Work is partially supported by grants from the State of Texas (ASE) & the Michelle foundation An adaptable architecture of a machine protection system (MPS) suitable for continuous wave (cw), high intensity accelerators like those proposed for Accelerator Driven Systems (ADS) for subcritical reactor strategies and heavy ion accelerators for the production of rare isotopes is presented. A system of databases, networks and nodes that can systematically and flexibly be reconfigured to rebalance the required metadata is used. Additional features include reconfigurable machine setup templates that can rigorously be tested with mirror redundant online backups, the utilization of external reconfigurable geometric algorithms for the data channels and the network distribution, and the inclusion of initial system requirements as well as envisioned upgrades.
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WEPWI010	Results from the First Single Cell Nb3Sn Cavity Coatings at JLab	cavity, niobium, accelerating-gradient, resonance	3509
	G.V. Eremeev JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Nb3Sn is a promising superconducting material for SRF applications and has the potential to exceed the limitations of niobium. We have used the recently commissioned Nb3Sn coating system to investigate Nb3Sn coatings on several single cell cavities by applying the same coating procedure on several different single cells with different history and pre-coating surface preparation. We report on our findings with four 1.5 GHz CEBAF-shape single cell and one 1.3 GHz ILC-shape single cavities that were coated, inspected, and tested.
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WEPWI011	Commissioning Results of Nb3Sn Cavity Vapor Diffusion Deposition System at JLab	cavity, niobium, SRF, vacuum	3512
	G.V. Eremeev, W.A. Clemens, K. Macha, H. Park, R.S. Williams JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Nb3Sn as a BCS superconductors with a superconducting critical temperature higher than that of niobium offers potential benefit in lower surface resistance at the same temperature and frequency for SRF cavities. A Nb3Sn vapor diffusion deposition system was built and commissioned at Jefferson Lab. As the part of the commissioning a single cell 1.5 GHz CEBAF-shaped cavity was coated in the built system. The cavity exhibited the superconducting transition at about 17.9 K. The low field quality factor was about 5x10⁹ at 4 K and 7x10⁹ at 2 K dropping with field to about 10⁹ at both temperatures at about 8 MV/m.
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WEPWI015	BNL 56 MHz HOM Damper Prototype Fabrication at JLab	niobium, cavity, HOM, vacuum	3521
	N.A. Huque, W.A. Clemens, E. Daly JLab, Newport News, Virginia, USA S. Bellavia, G.T. McIntyre, S.K. Seberg, Q. Wu BNL, Upton, Long Island, New York, USA
	A prototype Higher-Order Mode (HOM) Damper was fabricated at JLab for the Relativistic Heavy-Ion Collider’s (RHIC) 56 MHz cavity at Brookhaven National Laboratory (BNL). Primarily constructed from high RRR Niobium and Sapphire, the coaxial damper presented significant challenges in electron-beam welding (EBW), brazing and machining via acid etching. The results of the prototype operation brought about changes in the damper design, due to overheating braze alloys and possible multi-pacting. Five production HOM dampers are currently being fabricated at JLab. This paper outlines the challenges faced in the fabrication process, and the solutions put in place.
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WEPWI054	Design and Test of the RHIC CMD10 Abort Kicker	kicker, impedance, vacuum, coupling	3612
	H. Hahn, M. Blaskiewicz, K.A. Drees, W. Fischer, W. Meng, J.-L. Mi, C. Montag, C. Pai, J. Sandberg, N. Tsoupas, J.E. Tuozzolo, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Planned and unplanned thyratron pre-fire triggered beam dumps have been observed in the yellow ring that were associated with quenches of the superconducting main ring magnets as the proton intensities increased in the FY10¹³ run. The increasing vacuum level indicated beam induced kicker ferrite heating causing lower magnetic kick field at a nominal pulse current. In anticipation of higher current and shorter bunches in FY2015 an accelerator improvement program was initiated to reduce the longitudinal coupling impedance with changes to the eddy-current strip geometry using Opera simulations and to change the CMD5005 to CMD10 ferrite. Results of the standard impedance measurements and of pulse current in heating tests to 170 °C are reported. All 10 dump kickers are being modified and are encapsulated with a cooling system for installation in the rings.
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Paper

Title

Other Keywords

Page

MOBD3

Development of a 9 MHz 15 kW Solid-state CW Amplifier for RHIC

impedance, cavity, resonance, feedback

67

S.C. Dillon
Tomco Technologies, Stepney, South Australia, Australia

This paper describes the technical details of the development of a high-power solid-state amplifier for Brookhaven Laboratory. The amplifier must withstand short duration events of 100% full-power reflection, and also must guarantee delivery of continuous power into any load impedance at any angle.

Slides MOBD3 [10.800 MB]

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MOPJE070

Reduction of Electron Cloud in Particle Accelerator Beampipes Studied by RF Multipacting

electron, injection, vacuum, detector

472

R. Leber, F. Caspers, P. Costa Pinto, M. Taborelli
CERN, Geneva, Switzerland

For a given beam structure, chamber geometry and magnetic field configuration, the electron cloud (EC) intensity depends on the Secondary Electron Yield (SEY) of the beam pipe. The reduction of the EC density as a function of machine operation time (scrubbing) is attributed to the growth of a low SEY carbon film induced by electron bombardment. In this paper, we study the time evolution of the conditioning of stainless steel beam pipes in a laboratory setup. The EC or multipacting is induced by Radio-Frequency (RF) fields in a coaxial resonator under vacuum. Strip detectors are used to monitor the current of the EC. Induced pressure rise is simultaneously detected. The multipacting intensity shows a linear dependence on the positive DC bias voltage up to 1000 V, applied to the central electrode. An accelerated conditioning is observed for the applied bias voltage. The SEY of samples exposed to the EC is measured and the surface composition is monitored by X-ray Photoelectron Spectroscopy. The measured SEY, surface composition and multipacting behaviour are well correlated. The injection of acetylene and dodecane during multipacting proved to be ineffective in the conditioning.

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MOPMA004

Numerical Optimization of Accelerators within oPAC

simulation, lattice, controls, quadrupole

533

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485.
Powerful simulation tools are required for every accelerator and light source to study the motion of charged particles through electromagnetic fields during the accelerator design process, to optimize the performance of machine diagnostics and to assess beam stability and non-linear effects. The Optimization of Particle Accelerators (oPAC) Project is funded by the EU within the 7th Framework Programme and currently supports 23 Fellows that are based at institutions across Europe. This large network carries out R&D that closely links beam physics studies with the development of diagnostics and beyond state-of-the-art simulation tools. This contribution presents selected research outcomes from oPAC, including the numerical optimization of beam loss monitor locations along the European Spallation Source’s 5 MW proton linac, results from tracking studies for the LHeC lattice that allow beam stability to be assessed, and multi-objective optimization of the linear and non-linear beam dynamics of the synchrotron SOLEIL. In addition, an overview of recent and future oPAC events is also given.

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MOPTY001

Development of Wideband BPM for Precise Measurement of Internal Bunch Motion

impedance, coupling, feedback, synchrotron

937

K.G. Nakamura
Kyoto University, Kyoto, Japan
Y.H. Chin, T. Koseki, T. Obina, M. Okada, M. Tobiyama, T. Toyama
KEK, Ibaraki, Japan
Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Funding: This work was supported by MEXT KAKENHI Grant Number 25105002, Grant-in-Aid for Scientific Research on Innovative Areas titled “ Unification and　Development of the Neutrino Science Frontier”
To suppress intra-bunch oscillations and to reduce particle losses, the intra-bunch feedback (IBFB) system has been developed in 2014 for the J-PARC Main Ring (MR). A new BPM was also installed to the MR for the IBFB system. This BPM has a sufficient frequency response and position sensitivity(up to 1.5GHz within 15% fluctuation ). However, a better performance may be needed in future for more precise analysis of internal motions (e.g. due to an electron cloud). We report the development of the BPM and precise measurement results of the BPM characteristics. We also report simulation studies of the digital equalizer which helps to reconstructs the beam shape from beam signals.

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MOPTY063

The Flexible Customized Supervisor and Control System for Utility in TPS

controls, operation, monitoring, vacuum

1085

C.S. Chen, W.S. Chan, J.-C. Chang, Y.C. Chang, Y.-C. Chung, C.W. Hsu, C.Y. Liu, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

In order to maintain and operate a synchrotron radiation light source well requires quite a few efforts. All parts of the big machine, including vacuum system, all kinds of magnets, RF facility, cryogenic equipments, radiation security, optic devices and utility equipment must cooperate in harmony to provide high quality light. Any one of the above system contains lots of analog or digital signal transmission, not to mention the vast range of utility. Numbers of programmable automation controllers (PACs) are applied in utility system in TPS to ensure the utility operates normally. In addition to the high reliability and distribution, the flexible programmability of PAC is the most critical feature in this project. A well-designed program, Archive Viewer, provides a platform for showing these big data from all distributed systems. The architecture of the server system for utility is described in this paper as well.

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MOPTY065

Beam Stability of the Taiwan Light Source Storage Ring

betatron, storage-ring, electron, injection

1091

H.C. Chen, H.H. Chen, Y.-S. Cheng, S.J. Huang, C.H. Kuo, J.A. Li, Y.K. Lin
NSRRC, Hsinchu, Taiwan

The Taiwan Light Source Storage Ring (SR) has been in operation since many years ago. Maintaining best stability of the electron beam is becoming the main challenge. This study endeavored to improve the electron beam stability of The Taiwan Light Source Storage Ring (SR). Employing the artificial neural network (ANN)-constructed experiment design to analyze and optimize the storage ring betatron tunes .This report outlines the details of the beam stability process experiment.

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MOPTY070

Online RadFET Reader for Beam Loss Monitoring System

EPICS, controls, interface, radiation

1097

C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
NSRRC, Hsinchu, Taiwan

To investigate the beam loss and its distribution during operation of synchrotron light sources at NSSRC, a sixteen-channel readout box is designed and implemented to read the threshold voltage of the RadFETs installed at accelerator tunnel. To simplify the design, the reader plays a role of remote I/O for EPICS IOC. The IOC collects voltage from readers distributed in the accelerator to deduce the integrated dose and dose rate. User interface is shown in the control console for real-time display and the archived data are processed off-line.

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MOPWI028

Initial Experimental Results of a Machine Learning-Based Temperature Control System for an RF Gun

controls, gun, cavity, monitoring

1217

A.L. Edelen, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
B.E. Chase, D.J. Crawford, N. Eddy, D.R. Edstrom, E.R. Harms, J. Ruan, J.K. Santucci, P. Stabile
Fermilab, Batavia, Illinois, USA

Colorado State University (CSU) and Fermi National Accelerator Laboratory (Fermilab) have been developing a control system to regulate the resonant frequency of an RF electron gun. As part of this effort, we present experimental results for a benchmark temperature controller that combines a machine learning-based model and a predictive control algorithm for improved settling time, overshoot, and disturbance rejection relative to conventional techniques. Such improvements have implications for machine up-time and management of reflected power. This work is part of an on-going effort to develop adaptive, machine learning-based tools specifically to address control challenges found in particle accelerator systems.

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MOPWI049

Open XAL Services Architecture

interface, framework, software, Linux

1267

T.A. Pelaia II
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725
Open XAL is an accelerator physics software platform developed in collaboration among several facilities around the world. It includes a powerful new services extension that allows for natural remote procedure calls. The high level services interface is based upon custom implementations of modern standard protocols such as JSON-RPC and WebSockets. This choice of modern protocols allows for flexibility such as seamless communication with web clients free of plugins plus rich object type support. The JSON parser was designed for convenient data type transformations with easy extensibility, high performance and low memory overhead. The Open XAL services architecture features a simple application programming interface, high performance, memory efficiency and thread safety.

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TUAC3

Optimization of Beam Loss Monitor Network for Fault Modes

cavity, detector, simulation, lattice

1356

Z. Liu, Z.Q. He, S.M. Lidia, D. Liu, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Beam Loss Monitoring (BLM) System is an essential part to protect accelerator from machine faults. Compared with the empirical or uniform BLM arrangement in most accelerators, our new optimization approach proposes a “minimum spatial distribution” for BLM network. In this distribution, BLMs shall be placed at a small set of “critical positions” that can detect all failure / FPS trigger-able events of each fault mode. In additional, to implement a more advanced function of fault diagnosis, BLM should also be placed at “discrimination points” for fault-induced loss pattern recognition. With examples of FRIB failure event simulations, the author demonstrates the proof of concept to locate these “critical positions” and “discrimination points” for the minimum spatial distribution of BLMs.

Slides TUAC3 [2.341 MB]

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WEPWA015

RF Input Coupler for 20 K Cooled C-band 2.6-cell Photocathode RF Gun

cavity, simulation, gun, resonance

2522

T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai
LEBRA, Funabashi, Japan
M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan
T.S. Shintomi
Nihon University, Tokyo, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
For future use in a compact linac-driven X-ray source, a cryo-cooled C-band photocathode RF gun is under development. The RF experiment on the basic 2.6-cell test cavity has shown that the unloaded Q-value of the cavity at 20 K can be explained by the surface resistance based on the anomalous skin effect. Since the cavity was intended for preliminary experiments of the low temperature RF properties*, a new test cavity with an RF input coupler has been designed. The basic structure of the accelerating cells has not been changed from the previous cavity. Avoiding an element with a low cooling efficiency such as the inner electrode in a coaxial coupler, a simpler cylindrical input coupler has been designed. The coupler consists of a cylindrical TM01 mode waveguide and a mode converter from a rectangular TE10 mode, with both elements placed on the accelerating axis. The structure and the dimensions of the coupler have been determined using the 3-D simulation code CST Studio so that the resonant frequency of the whole system and the coupling coefficient of the coupler meet the specifications of the RF gun. The new test cavity will be completed early in 2015 at KEK.
* T. Tanaka et al., Proceedings of IPAC2014, 658-660, http://accelconf.web.cern.ch/AccelConf
/IPAC2014/papers/mopri030.pdf

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WEPMA047

MHI's Production Activities of Accelerator Components

status, coupling, LLRF, vacuum

2873

N. Shigeoka, S. Miura
MHI, Hiroshima, Japan

Mitsubishi Heavy Industries (MHI) is manufacturing various types of accelerator components. Recent production activities, mainly in a field of a normal conducting RF, will be reported in this presentation.

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WEPMN004

Progress on the CSNS Power Supply System

power-supply, controls, dipole, proton

2921

X. Qi, H. Geng
IHEP, Beijing, People's Republic of China

The 1.6 GeV proton synchrotron proposed in the CSNS Project is a 25 Hz rapid-cycling synchrotron (RCS) with injection energy of 80 MeV. Beam power is aimed to 100 kW at 1.6 GeV. The power supply system consists of seven subsystems. Those power supplies have three operation modes: DC mode, AC plus DC mode and programmable pulse mode. This paper will introduce the Power supply system status in recent years.
Power Supply, rapid-cycling synchrotron, serial resonant network

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WEPMN026

Development of Non-resonant Perturbing Method for Tuning Traveling Wave Deflecting Structures

simulation, cavity, higher-order-mode, dipole

2985

J.H. Tan, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D.C. Tong
TUB, Beijing, People's Republic of China

For traveling wave accelerating structures, the tuning method assisted by bead pull technique based on non-resonant perturbation field distribution measurement has been widely used. Long periodic traveling wave deflecting structure, which operating at HEM11 mode, is difficult to use non-resonant perturbation method, and a improved method has been developed for measuring and tuning by "cage" type perturbing object at SINAP. The measurements on x-band traveling wave deflecting structure are presented in this paper.

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WEPMN052

A New RF Laboratory for Developing Accelerator Cavities at the University of Huelva

cavity, ion, heavy-ion, rfq

3046

I. Martel, C. Bonțoiu, J.A. Dueñas, D. Gordo-Yáñez, A.K. Orduz, J. Sanchez-Segovia
University of Huelva, Huelva, Spain

The University of Huelva is presently involved in R&D projects for developing RF accelerator cavities. Two types of cavities are presently under design, a prototype of room temperature RFQ injector and a quarter-wave resonator for high intensity heavy-ion linear accelerators. The laboratory is equipped with dedicated test-bench for RF measurements, which includes high-power RF generators, network analyzer, amplifiers and power meters. A clean room is also available having a dedicated space for high-precision mechanical metrology and cavity mounting, together with a vertical cryostat for superconducting cavity test.

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WEPMN070

Measurement Techniques and Application of Combined Parallel/Orthogonal Magnetic Bias on a Ferrite Tuned Resonator in Low Frequency Range (3-10 MHz)

impedance, cavity, solenoid, power-supply

3087

G. Favia, F. Caspers, M. Morvillo, C. Rossi, C. Vollinger
CERN, Geneva, Switzerland

We present several measurement methods for evaluation of magnetic properties of magnetically biased and non-biased ferrite samples in a coaxial test fixture. One important aspect is the crosscheck of results obtained by using different and independent measurement and evaluation methods. Since a rather high DC bias current has to be applied, a dedicated network was designed that allows the passage of up to 50 A DC without degradation of the RF performance. With a combination of calibration methods and a compensating topology with two identical sample holders, a good performance was achieved. In this context, magnetic material parameters for about 10 different types of ferrite were obtained. The orthogonal magnetic bias was added by placing the entire test fixture into a large toroidal coil. Thus, the bias field can be supplied independently from, and in addition to the classical parallel bias. An optimal combination between the two biasing fields was found, resulting in a reduction of magnetic losses up to 50% on certain ferrites. We show that the mixed magnetization, normally used for garnets only, is beneficial also for other types of ferrites.

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WEPHA002

Electromagnetic Characterization of NEG Properties Above 200 GHz for the CLIC Damping Rings

simulation, impedance, damping, electron

3097

E. Koukovini-Platia, G. Iadarola, G. Rumolo, C. Zannini
CERN, Geneva, Switzerland

Non-Evaporable Getter (NEG) will be used in the CLIC electron damping rings (EDR) to suppress fast beam ion instabilities due to its effective pumping ability. The electromagnetic (EM) characterization of the NEG properties up to high frequencies is required for the correct impedance modeling of the DR components. The properties are determined using WR-3.4 and WR-1.5 rectangular waveguides, based on a combination of experimental measurements of the complex transmission coefficient S21 with a Vector Network Analyzer (VNA) and CST 3D EM simulations, for the frequency range of 220-330 GHz and 500-750 GHz. The results obtained using NEG-coated Aluminum (Al) waveguides are presented in this paper.

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WEPHA025

Design of a Variable X-band RF Power Splitter

impedance, polarization, operation, scattering

3167

H. Zha, A. Grudiev, D. Gudkov, I. Syratchev
CERN, Geneva, Switzerland

The design of a two output ports, high power X-Band RF splitter with arbitrary split ratio is presented. This ratio is adjusted by mechanical changing the position a special RF short circuit piston. The piston is mounted on a step-motor providing the precise movement. Special measures were taken in the design to decrease the maximum electrical field on the cooper surface, as well as to maximise the bandwidth of the device. This splitter will be tested in the high power X-band test stand at CERN.

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WEPHA030

EMI Measurement for TPS Booster Kicker and Septum Systems

septum, kicker, booster, injection

3179

Y.-H. Liu, W.S. Chan, C.S. Chen, J.-R. Chen
NSRRC, Hsinchu, Taiwan

The purpose of this paper is to estimate the conducted and radiated Electromagnetic Interference (EMI) for subsystems in the TPS booster ring. A LISN (Line Impedance Stabilizing Network) system with a wide frequency range was conducted to measure the EMI spectrum of pulsed magnet system. The radiated EMI was tested by magnetic field probe, which the measurement frequency range is 100 kHz ~ 3 GHz. A stray current was tested by wide frequency current transformer in order to measure the conducted current for kicker and septum systems. According to the experiment results, the stray current could flow through the other subsystems or booster chamber, and it might be affected the stability of booster operation. Therefore reducing and eliminating the interference of EM waves will be a very important issue. The EMI prevention scheme will be continued.

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WEPHA044

Alignment Design and Status of Taiwan Photon Source

survey, alignment, storage-ring, booster

3212

W.Y. Lai, M.L. Chen, P.S.D. Chuang, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, C.J. Lin, S.Y. Perng, T.C. Tseng, H.S. Wang
NSRRC, Hsinchu, Taiwan

After the construction of Taiwan Photon Source (TPS) was finished, the variation of the survey fiducials was stable. However, the following precise alignment work is concerned by the change of temperature critically. In this paper, the whole process of alignment work in the TPS storage ring with the relation of survey network and thermal issues of the environment will be described. We analysed these survey data so that the correction of survey network could be estimated by the change of temperature, thus all the elements for example, booster, pedestals, and girders could be positioned within the shortest time.

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WEPHA053

Surface Resistance RF Measurements of Materials Used for Accelerator Vacuum Chambers

cavity, coupling, factory, resonance

3235

P. Goudket, L. Gurran, O.B. Malyshev, M.D. Roper, R. Valizadeh, S. Wilde
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, L. Gurran
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, O.B. Malyshev, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S. Wilde
Loughborough University, Loughborough, Leicestershire, United Kingdom

The RF surface resistance of accelerator vacuum chamber walls can have a significant impact on the beam quality. There is a need to know how the use of a new material, surface coating or surface treatment can affect the RF surface resistance. ASTeC and Lancaster University have designed and built two test cavities where one face can be replaced with a sample in the form of a flat plate. The measurements are performed with a network analyser at the resonant frequency of approximately 7.8 GHz.

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WEPHA057

High Gradient Testing of an X-band Crab Cavity at XBox2

cavity, wakefield, klystron, electron

3242

B.J. Woolley, P.K. Ambattu, R. Apsimon, G. Burt, A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A. Grudiev, I. Syratchev, R. Wegner, B.J. Woolley, W. Wuensch
CERN, Geneva, Switzerland

CERN’s Compact linear collider (CLIC) will require crab cavities to align the bunches to provide effective head-on collisions. An X-band quasi-TM11 deflecting cavity has been designed and manufactured for testing at CERN’s Xbox-2 high power standalone test stand. The cavity is currently under test and has reached an input power level in excess of 40MW, with a measured breakdown rate of better than 10^-5 breakdowns per pulse. This paper also describes surface field quantities which are important in assessing the expected BDR when designing high gradient structures.

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WEPTY002

Studies into Electron Beam Generation, Acceleration and Diagnostics within LA³NET

laser, acceleration, electron, diagnostics

3256

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

The Laser Applications at Accelerators Network (LA³NET) is receiving funding of up to 4.6 M€ from the European Union within the 7th Framework Programme to carry out R&D into laser-based particle sources, laser acceleration schemes and laser-based beam diagnostics. This international network joins universities, research centres and private companies and has been training 19 early stage researchers at network nodes across Europe since 2011. This contribution presents research outcomes from LA³NET’s main work packages, covering electron beam generation, acceleration and diagnostics. Results from surface studies of photocathodes for photo injector applications in the framework of the CLIC project are presented along with information about expected accelerating gradients in dielectric laser-driven accelerators as identified for non-relativistic and relativistic electron beams using the CST and VSIM simulation codes. Initial results from energy measurements using Compton backscattering at the ANKA Synchrotron at KIT are also presented. In addition, a summary of recent and upcoming international events organized by the LA³NET consortium is also given.
This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191.

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WEPTY011

Power Supply Conceptual Design and R&D for the APS Upgrade

power-supply, interface, controls, FPGA

3276

J. Wang, B. Deriy, T. Fors, R.T. Keane, B. Song
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 MBA upgrade for the APS requires a large number of power supplies with either unipolar or bipolar DC output currents. The unipolar power supplies will be used to power the main coils in the dipole, quadrupole, and sextupole magnets and the bipolar power supplies will be used for the trim or correction coils. There are several demanding requirements of the power supplies. The unipolar power supplies are expected to have a current stability within 10 parts per million (ppm) of the full scale. The currents must be calibrated to the specification and confirmed with independent and accurate measurement. The bipolar power supplies for the fast correction magnets are required to have a wide output current bandwidth in order to minimize the impact on the real-time feedback system for the beam position correction. There are also new requirements for the power supply controls and communications that are much more demanding than that in the existing APS accelerators. This paper will report the conceptual designs of the power supply systems and the R&D program that is developed to find solutions to the technical challenges.

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WEPTY043

Short Pulse Marx Modulator

high-voltage, controls, flattop, collider

3370

R.A. Phillips, M.P.J. Gaudreau, M.K. Kempkes, B.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA
J.A. Casey
Rockfield Research Inc., Las Vegas, Nevada, USA

Funding: DE-SC0004251
High energy, short-pulse modulators are being re-examined for the Compact Linear Collider (CLIC) and numerous X-Band accelerator designs. At the very high voltages required for these systems, all of the existing designs are based on pulse transformers, which significantly limit their performance and efficiency. There is not a fully optimized, transformer-less modulator design capable of meeting the demanding requirements of very high voltage pulses at short pulse widths. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) has completed development of a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort were modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies.

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WEPTY046

Progress on the MICE 201 MHz Cavities at LBNL

cavity, Windows, coupling, simulation

3378

T.H. Luo, A.J. DeMello, A.R. Lambert, D. Li, S. Prestemon, S.P. Virostek
LBNL, Berkeley, California, USA

The international Muon Ionization Cooling Experiment aims to demonstrate the transverse cooling of amuon beam by ionization in energy absorbers. The final MICE cooling channel configuration has two RF modules, each housing a 201 MHz RF cavity used to compensate the longitudinal energy loss in the absorbers. The LBNL team has designed and fabricated all MICE RF cavities. The cavities will be post-processed and RF measured before being installed in the RF modules. We present the recent progress on this work, including the low level RF measurement on cavity body and Be windows, the electro-polishing (EP) on the cavity surface, the numerical simulation on cavity Be window detuning, and the ongoing mechanical designing work of cavity components.

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WEPTY057

Adaptable Machine Protection Architecture for CW, High Intensity Accelerators

database, operation, framework, real-time

3402

S. Assadi
Texas A&M University, College Station, Texas, USA

Funding: Work is partially supported by grants from the State of Texas (ASE) & the Michelle foundation
An adaptable architecture of a machine protection system (MPS) suitable for continuous wave (cw), high intensity accelerators like those proposed for Accelerator Driven Systems (ADS) for subcritical reactor strategies and heavy ion accelerators for the production of rare isotopes is presented. A system of databases, networks and nodes that can systematically and flexibly be reconfigured to rebalance the required metadata is used. Additional features include reconfigurable machine setup templates that can rigorously be tested with mirror redundant online backups, the utilization of external reconfigurable geometric algorithms for the data channels and the network distribution, and the inclusion of initial system requirements as well as envisioned upgrades.

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WEPWI010

Results from the First Single Cell Nb3Sn Cavity Coatings at JLab

cavity, niobium, accelerating-gradient, resonance

3509

G.V. Eremeev
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Nb3Sn is a promising superconducting material for SRF applications and has the potential to exceed the limitations of niobium. We have used the recently commissioned Nb3Sn coating system to investigate Nb3Sn coatings on several single cell cavities by applying the same coating procedure on several different single cells with different history and pre-coating surface preparation. We report on our findings with four 1.5 GHz CEBAF-shape single cell and one 1.3 GHz ILC-shape single cavities that were coated, inspected, and tested.

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WEPWI011

Commissioning Results of Nb3Sn Cavity Vapor Diffusion Deposition System at JLab

cavity, niobium, SRF, vacuum

3512

G.V. Eremeev, W.A. Clemens, K. Macha, H. Park, R.S. Williams
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Nb3Sn as a BCS superconductors with a superconducting critical temperature higher than that of niobium offers potential benefit in lower surface resistance at the same temperature and frequency for SRF cavities. A Nb3Sn vapor diffusion deposition system was built and commissioned at Jefferson Lab. As the part of the commissioning a single cell 1.5 GHz CEBAF-shaped cavity was coated in the built system. The cavity exhibited the superconducting transition at about 17.9 K. The low field quality factor was about 5x10⁹ at 4 K and 7x10⁹ at 2 K dropping with field to about 10⁹ at both temperatures at about 8 MV/m.

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WEPWI015

BNL 56 MHz HOM Damper Prototype Fabrication at JLab

niobium, cavity, HOM, vacuum

3521

N.A. Huque, W.A. Clemens, E. Daly
JLab, Newport News, Virginia, USA
S. Bellavia, G.T. McIntyre, S.K. Seberg, Q. Wu
BNL, Upton, Long Island, New York, USA

A prototype Higher-Order Mode (HOM) Damper was fabricated at JLab for the Relativistic Heavy-Ion Collider’s (RHIC) 56 MHz cavity at Brookhaven National Laboratory (BNL). Primarily constructed from high RRR Niobium and Sapphire, the coaxial damper presented significant challenges in electron-beam welding (EBW), brazing and machining via acid etching. The results of the prototype operation brought about changes in the damper design, due to overheating braze alloys and possible multi-pacting. Five production HOM dampers are currently being fabricated at JLab. This paper outlines the challenges faced in the fabrication process, and the solutions put in place.

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WEPWI054

Design and Test of the RHIC CMD10 Abort Kicker

kicker, impedance, vacuum, coupling

3612

H. Hahn, M. Blaskiewicz, K.A. Drees, W. Fischer, W. Meng, J.-L. Mi, C. Montag, C. Pai, J. Sandberg, N. Tsoupas, J.E. Tuozzolo, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Planned and unplanned thyratron pre-fire triggered beam dumps have been observed in the yellow ring that were associated with quenches of the superconducting main ring magnets as the proton intensities increased in the FY10¹³ run. The increasing vacuum level indicated beam induced kicker ferrite heating causing lower magnetic kick field at a nominal pulse current. In anticipation of higher current and shorter bunches in FY2015 an accelerator improvement program was initiated to reduce the longitudinal coupling impedance with changes to the eddy-current strip geometry using Opera simulations and to change the CMD5005 to CMD10 ferrite. Results of the standard impedance measurements and of pulse current in heating tests to 170 °C are reported. All 10 dump kickers are being modified and are encapsulated with a cooling system for installation in the rings.

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