IPAC2018 - List of Keywords (klystron)

Paper	Title	Other Keywords	Page
MOYGB1	Status and Future Strategy for Advanced High Power Microwave Sources for Accelerators	electron, cavity, operation, linac	12
	F. Gerigk CERN, Geneva, Switzerland
	The need for more energy efficient high power microwave devices for accelerator applications continues to increase. This is important for development of cost effective accelerator designs that are coming up in the near future. Efforts are already in place to design new devices that could stretch the limits of RF power conversion to the highest levels possible. Devices including new technologies and design innovations like multi beam, increased number of cavities designs are being considered. Advances in the application of solid state amplifiers to accelerators are also being realized. This invited talk will cover the recent advances and status of such efforts. It will discuss future needs and a strategy for pursuing these efforts on a faster time scale for the benefit of the accelerator community.
	Slides MOYGB1 [11.575 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOYGB1
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TUPAF017	Stability Analysis of the TOP-IMPLART 35 MeV Proton Beam	DTL, linac, proton, booster	697
	P. Nenzi, A. Ampollini, G. Bazzano, L. Picardi, C. Ronsivalle, V. Surrenti, E. Trinca, M. Vadrucci ENEA C.R. Frascati, Frascati (Roma), Italy
	Funding: The TOP-IMPLART program is funded by Regione Lazio. The TOP-IMPLART (Intensity Modulated Proton Linear Accelerator for RadioTherapy) is the demonstrator of a 150 MeV proton linear accelerator devoted to cancer treatment application under development at ENEA-Frascati. It is a full linear machine composed by a 425 MHz 7 MeV injector and a high frequency linac operating at 2997.92 MHz. The first accelerating section, installed and in operation, consists of 4 SCDTL structures and delivers a 35 MeV beam in 3 microseconds pulses at a maximum repetition frequency of 50 Hz. The principal advantage of a linear accelerator, in a therapeutic application, is the quick setting possibility (up to pulse-to-pulse, in principle) of the physical properties of the proton beam, offering larger flexibility (compared to traditional circular designs) and improved precision on dose delivery to the patient., The short and long range stability of the machine have been analyzed measuring on a pulse by pulse basis both the output beam characteristics and other machine parameters in order to identify those that mainly affect the beam stability. This work describes the methodology used in this study, the main results achieved and the future developments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF017
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TUZGBF5	KlyLac Prototyping for Borehole Logging	linac, cavity, feedback, simulation	1244
	A.V. Smirnov, R.B. Agustsson, M.A. Harrison, A.Y. Murokh, A.Yu. Smirnov RadiaBeam Systems, Santa Monica, California, USA S. Boucher, T.J. Campese, K.J. Hoyt RadiaBeam, Los Angeles, California, USA E.A. Savin MEPhI, Moscow, Russia A.A. Zavadtsev Nano, Moscow, Russia
	Funding: Work supported by the U.S. Department of Energy (award No. DE-SC0015721) Linac-based system for borehole logging exploits KlyLac approach combing klystron and linac sharing the same electron beam, vacuum volume, and RF network enabling self-oscillation due to a positive feedback. The KlyLac prototype design tailors delivering ~1 MeV electrons in a linac section using part of the beam injected from a sheet beam klystron (SBK). The linac part is based on a very robust, high group velocity, cm-wave, and a standing wave accelerating structure of a 'cross-pin' type supplied by a sampler. The SBK part features a permanent magnet solenoid focusing, relatively low voltage, and high aspect ratio beam. The main SBK characteristics (perveance, power, and efficiency) are expected to be similar to that for a magnetron.
	Slides TUZGBF5 [3.280 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF5
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TUPMF037	Development of New Operational Mode for NSLS-II Injector: Low Energy 100MeV Linac-to-Booster Injection	booster, injection, operation, linac	1330
	X. Yang, A.A. Derbenev, R.P. Fliller, T.V. Shaftan, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	The NSLS-II injector consists of a 200 MeV linac and a 3 GeV full-energy booster synchrotron. The linac contains five traveling-wave S-band accelerating structures driven by two high-power klystrons, with a third klystron as spare. In the event that the spare klystron is not available, the failure of one klystron will prohibit the linac from injecting into the booster as the energy is too low. Therefore, we wish to develop a new operational mode that the NSLS-II injector can operate with a single klystron providing 100 MeV beam from the linac. A decremented approach with intermediate energies 170 MeV, 150 MeV, etc., takes advantages of pre-calculated booster ramps and beam based online optimization. By lowering the booster injection energy in a small step and online optimizing at each step, we were able to achieve 100 MeV booster injection. 170 MeV operation mode of the NSLS-II injector has been implemented since May 31, 2017, with a similar overall performance compared to the standard 200 MeV operation but fewer klystron trips. 100 MeV single-klystron operation has been successfully demonstrated with 20-30% overall efficiency, which is limited by booster acceptance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF037
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WEXGBF1	Testing of the ESS MB-IOT Prototypes	linac, cavity, operation, electron	1759
	M. Jensen ESS, Lund, Sweden C. Bel, A. Beunas, D. Bussiere, P. Cacheux, V. Hermann, J.C. Racamier, C. Robert TED, Thonon, France M. Boyle, H. Schult L-3, Williamsport, Pennsylvania, USA G. Cipolla, E. Montesinos, M.S.B. Sanchez Barrueta CERN, Geneva 23, Switzerland T. Kimura, P.E. Kolda, P. Krzeminski, L. Kurek, S. Lenci, O.S. Sablic, L. Turek, C. Yates CPI, Palo Alto, California, USA M.F. Kirshner LANL, Los Alamos, New Mexico, USA R.D. Kowalczyk, A.V. Sy, B.R. Weatherford SLAC, Menlo Park, California, USA A. Zubyk L3 EDD, Williamsport, USA
	ESS is considering the use of MB-IOTs for parts of the high-beta linac. Two prototypes have been built by indus-try, namely L3 and CPI/Thales and have passed the factory acceptance test with excellent results. Both tubes will go through further extensive testing at CERN for ESS follow-ing delivery and a final decision on tube technology will be taken in April 2018. This invited talk presents the back-ground for the technical decision of IOTs vs klystrons, associated impact for ESS, and latest plans for industrial production of these IOTs for ESS.
	Slides WEXGBF1 [9.836 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBF1
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WEPAF022	Application of Machine Learning to Minimize Long Term Drifts in the NSLS-II Linac	linac, network, operation, booster	1867
	R.P. Fliller, C. Gardner, P. Marino, R.S. Rainer, M. Santana, G.J. Weiner, X. Yang, E. Zeitler BNL, Upton, Long Island, New York, USA
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy Machine Learning has proven itself as a useful technique in a variety of applications from image recognition to playing Go. Artificial Neural Networks have certain advantages when used as a feedforward system, such as the predicted correction relies on a model built from data. This allows for the Artificial Neural Network to compensate for effects that are difficult to model such as low level RF adjustments to compensate for long term drifts. The NSLS-II linac suffers from long terms drifts from a number of sources including thermal drifts and klystron gain variations. These drifts have an effect on the injection efficiency into the booster, and if left unchecked, portions of the bunch train may not be injected into the booster, and the storage ring bunch pattern will ultimately suffer. In this paper, we discuss the application of Artificial Neural Networks to compensate for long term drifts in the NSLS-II linear accelerator. The Artificial Neural Network is implemented in python allowing for rapid development of the network. We discuss the design and training of the network, along with results of using the network in operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF022
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WEPAF076	Availability Studies Comparing Drive Beam and Klystron Options for the Compact Linear Collider	operation, simulation, linac, software	2013
	O. Rey Orozko, S. Döbert, M. Jonker CERN, Geneva, Switzerland
	The initial proposal for the Compact Linear Collider (CLIC) is based on a two beam-scheme to accelerate the main colliding beams. For low collision energies, the main beam could also be accelerated by powering the accelerating structures with klystrons instead of the two-beam scheme. This paper studies the feasibility of this new alternative in terms of machine availability. An implemented bottom-up availability model considers the components failure modes to estimate the overall availability of the system. The model is defined within a Common Input Format scheme and the AvailSim3 software package is used for availability simulations. This paper gives an overview of the systems affecting the beam powering availability and makes recommendations for availability improvements.
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WEPAK018	LLRF Control Unit for SuperKEKB Injector Linac	controls, LLRF, linac, timing	2134
	T. Miura, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Matsumoto, F. Qiu, Y. Yano KEK, Ibaraki, Japan N. Liu Sokendai, Ibaraki, Japan
	The low-level RF (LLRF) control unit based on the digital system has been developed for a stable and high precision pulse modulation for the SuperKEKB. The RF pulse is changed at a 50-Hz repetition rate for the top-up injection to four different rings by the event system. The LLRF control unit has not only the pulse modulator, but also other functions: VSWR meter, RF monitor, event receiver (EVR), and pulse-shortening detection.
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WEPAL022	Operating Experience of Water Cooling System in the J-PARC LINAC and RCS	linac, acceleration, diagnostics, DTL	2203
	K. Suganuma, K. Fujirai, M. Kinsho, P.K. Saha, Y. Yamazaki JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The cooling system for the J-PARC LINAC and RCS uses a total of 25 circulation pumps to cool the accelerator devices. In February 2017, we experienced damage of circulation pumps due to low flow rate, and started the development of an abnormality detection system concentrating on the vibration measurements of the circulation pumps. In this report, the vibration measurement results of the coolant circulation pumps and the development status of abnormality detection through multivariate analysis using vibration values are discussed.
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WEPAL023	Pulsed Operation at MAMI with High Beam Loading	experiment, beam-losses, operation, beam-loading	2206
	M. Dehn, K. Aulenbacher, F. Fichtner, P. Jennewein, W. Klag, H.-J. Kreidel, J.R. Röthgen IKP, Mainz, Germany
	Funding: Work supported by DFG (CRC 1044) and the German federal state of Rhineland-Palatinate The Mainz Microtron Accelerator (MAMI) is a microtron cascade which is normally operated CW for particle physics experiments. For certain investigations it is necessary to use a pulsed beam (macro pulses, several milliseconds). Up to now this pulsed mode can only be applied if the beam loading for the accelerating RF structures is negligible. To achieve higher pulse intensities the accelerator RF infrastructure needs to be equipped with feed-forward techniques to compensate for the expected beam loading. To monitor beam losses the machine protection system at MAMI needs to be extended to be able to localize fast occurrences of beam losses. This paper will present the possibilities being investigated to allow pulsed operation of MAMI within the near future.
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WEPMF030	Optimization of Klystron Efficiency with MOGA	cavity, electron, simulation, bunching	2419
	C. Meng, X. He, S. Pei, S.C. Wang, O. Xiao, Z.S. Zhou IHEP, Beijing, People's Republic of China
	As the very important element of accelerator the klystron provide power to cavities for accelerating. Considering the accelerator cost of construction and running, the improvement of klystron efficiency is one developing hotspot of klystron research. In this paper the optimization method of klystron efficiency with MOGA based on 1D simulation program is proposed and the influences on klystron efficiency will be discussed.
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WEPMF033	RF Study And Cold Test of an S-band Spherical Cavity Pulse Compressor	cavity, coupling, simulation, vacuum	2429
	J. Lei, X. He, M. Hou, X.P. Li, G. Pei, H. Wang, J.B. Zhao IHEP, Beijing, People's Republic of China S. Shu Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	An S-band (2856 MHz) spherical cavity pulse compressor has been designed, fabricated and tested in the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS). The pulse compressor consists of a special 3 dB coupler and only one spherical energy storage cavity, two TE114 modes are chosen to oscillate in which for fairly high unload Q factor. The prototype was made of aluminum for studying the performance of the pulse compressor and checking the validity of the simulations. The cold test results of the aluminum cavity are also presented. The copper coating on the whole internal surface of the aluminum spherical cavity is in progress and the test results will also be presented in the future.
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WEPMF053	XFEL Modulators with Pulse Cables	FEL, operation, linac, radiation	2487
	H.-J. Eckoldt, S. Choroba, T. Grevsmühl, A. Hauberg, J. Havlicek, N. Heidbrook, K. Machau, N. Ngada DESY, Hamburg, Germany M. Frei, S.G. Keens, T.H. Strittmatter Ampegon AG, Turgi, Switzerland H. Leich DESY Zeuthen, Zeuthen, Germany
	The modulators of the European XFEL produce high voltage, at the 10kV level, having a power of up to 16.8 MW for 1.54 ms. The operation frequency of the super-conducting inac is 10 Hz. The series production of the 29 modulators started in 2012. The first modulator began operation in 2014 and the start of linac was beginning 2017. The R&D phase for the modulators started directly with the development of superconducting cavities. Besides the pulse generation, the modulator had to suppress the 10 Hz repetition rate in order not to disturb the grid. Another unique demand was the development of pulse cables. Since the power RF had to be generated in the tunnel, the klystrons were installed near the cavities. However, the modulators had to be installed outside of the tunnel for space, maintenance reasons and radiation concerns. This transmission of high power pulses via long cables is unique in the world and the suppression of EMI effects was mandatory. During the first year operation no EMI disturbances of other systems were detected and the modulator system works as expected.
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WEPMF063	Thyratron Replacement*	operation, high-voltage, linear-collider, collider	2512
	I. Roth, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: Funded under US DOE grant no. DE-SC0011292. Thyratrons are typically used as the switch in high power, short pulse modulators with pulse-forming networks. However, thyratrons have a lifetime of only ten to twenty thousand hours, their reservoir heater voltage needs to be adjusted periodically, and reduced overall demand has led multiple thyratron vendors to slow or cease production. In contrast, solid-state switches have a much longer lifetime, need no maintenance, and are based on widely-available commercial items. Despite these advantages, solid-state devices have not historically seen use, due to limited voltage, current, and risetime. Diversified Technologies, Inc. (DTI) has removed this barrier, having developed, built, and tested a thyratron-replacement switch for SLAC based on an array of series and parallel-connected commercial insulated-gate bipolar transistors (IGBTs). This switch has demonstrated operation at very high voltage and current, meeting the full specifications required by SLAC to completely replace (form-fit-function-interface) the L-4888 thyratron: 48 kV, 6.3 kA, and 1 μs risetime.
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WEPMF064	Daresbury Laboratory Short Pulse Klystron Modulators	high-voltage, operation, power-supply, factory	2515
	C. Chipman, M.P.J. Gaudreau, L. Jashari, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA S.A. Griffiths, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.J. Zhang Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
	Diversified Technologies, Inc. (DTI) has developed a unique short pulse klystron modulator system for the Compact Linear Advanced Research Accelerator (CLARA) Project at Daresbury Laboratory. One unit has been delivered and three more are on contract. This system is based on the combination of a high voltage solid-state switch, with a conventional 1:7 pulse transformer, and a passive pulse corrector with automated adjustment. This unique passive circuitry delivers the extremely flat output pulse required for advanced accelerator applications. The CLARA modulators share design elements with previous DTI modulators which provides both a lower cost and easier to maintain system. The modulators are designed to pulse 80 MW-class klystrons at an avg power of 250 kW and provides adjustable high efficiency operation in the 45 kV to 450 kV range for currents up to 545 A and pulse lengths of 1.5 to 4.0 μs. One key objective of modulator development is optimization of voltage flatness (± 0.02 %), stability (± 0.05 %), and reproducibility (± 0.05 %).
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THPAL005	Construction and Commissioning of the S-Band High-Gradient RF Laboratory at IFIC	network, GUI, linac, cathode	3619
	D. Esperante Pereira, C. Blanch Gutiérrez, M. Boronat, J. Fuster, D. Gonzalez Iglesias, A. Vnuchenko IFIC, Valencia, Spain N. Catalán Lasheras, G. McMonagle, I. Syratchev, W. Wuensch CERN, Geneva, Switzerland A. Faus-Golfe LAL, Orsay, France B. Gimeno UVEG, Burjasot (Valencia), Spain
	An S-Band High-Gradient (HG) Radio Frequency (RF) laboratory is under construction and commissioning at IFIC. The purpose of the laboratory is to perform investigations of high-gradient phenomena and to develop normal-conducting RF technology, with special focus on RF systems for hadron-therapy. The layout of the facility is derived from the scheme of the Xbox-3 test facility at CERN* and uses medium peak-power (7.5 MW) and high repetition rate (400 Hz) klystrons, whose RF output is combined to drive two testing slots to the required power. The design and construction of the various components of the system started in 2016 and has been completed. The installation and commissioning of the laboratory is progressing, with first results expected before mid 2018. The technical characteristics of the different elements of the system and the commissioning status together with preliminary results are described. * N. Catalan Lasheras, et al., 'Commissioning of Xbox3: a very high capacity X-band RF test stand', Proc. LINAC2016, East Lansing, USA, September 2016.
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THPAL027	Transverse RF Deflecting Structures for the MAX IV LINAC	GUI, linac, polarization, emittance	3684
	D. Olsson, F. Curbis, E. Mansten, S. Thorin, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). A soft X-ray Laser (SXL) beamline will also be installed in the end of the existing LINAC. For SPF and SXL operation, it is important to characterize beam parameters such as bunch profile, slice energy spread and slice emittance. For these measurements, two 3 m long transverse deflecting RF structures with a matching section are being developed. The structures are operating at S-band and have variable polarizations. When fed via a SLED pulse compressor, the two structures can generate a total integrated deflecting voltage higher than 100 MV which is sufficient for measurements with temporal resolutions down to 1 fs. This paper describes the initial RF design of the deflecting structures.
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THPAL053	Perveance Measurement of the TLS-Linac Klystron and the Evaluation of Its Operation Performance	electron, operation, cathode, linac	3763
	H.H. Chen, C.H. Kuo, K.-K. Lin, Y.-H. Liu NSRRC, Hsinchu, Taiwan
	The high power klystron is a radio frequency amplifier for TLS linac operation. It is a crucial device for electron acceleration in linac. How to evaluate its efficiency, lifetime and performance of klystron in operation is one of the major concern in this report. The key klystron parameter perveance is introduced and used for performance evaluation and operation status monitoring. It is important to execute periodic monitoring on perveance for ensuring a stable linac operation. Klystron characteristics diagnostics can be achieved through perveance measurement. A couple of klystron diagnostic parameters concerning perveance are explored for field examination purpose. Perveance comparison with factory acceptance test data is also presented.
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THPAL060	Advanced Modeling of Klystrons by the Tesla-Family of Large-Signal Codes	cavity, impedance, experiment, simulation	3785
	I.A. Chernyavskiy, D.K. Abe, B. Levush, A.N. Vlasov NRL, Washington, DC, USA T.M. Antonsen UMD, College Park, Maryland, USA T.M. Antonsen Leidos Corp, Billerica, MA, USA J. Rodgers Naval Research Laboratory (NRL), Washington, USA
	Funding: US Office of the Naval Research Klystrons and IOTs are widely used or proposed to be used in accelerators as high-power RF sources. Development and optimization of klystron and IOT designs is aided by the use of different simulation tools, including highly efficient large-signal codes. We present an overview of the advances in the code development and modeling using Naval Research Laboratory (NRL) set of TESLA-family of large-signal codes, suitable for the modeling of single-beam and multiple beam klystrons and IOTs. Original 2D large-signal algorithm of the code TESLA* was developed for the modeling of klystrons based on (relatively) high Q resonators and is applicable to the multiple-beam devices in an approximation of identical beams/beam-tunnels. Parallel extension of TESLA algorithm (code TESLA-MB) enabled an accurate, quasi-3D modeling of multiple-beam devices with non-identical beams/beam-tunnels. Recently developed more general TESLA-Z algorithm* is based on the impedance matrix approach and enabled geometry-driven large-signal modeling. Examples of applications of TESLA-family of codes to the modeling of advanced single-beam and multiple-beam klystrons (and IOTs) will be presented. A.N. Vlasov, et al,IEEE TPS, v.30(3), 1277-1291, June 2002 I.A. Chernyavskiy, et al.,IEEE TPS, v.36(3), 670-681, June 2008 **I.A. Chernyavskiy, et al.,IEEE TED, v.64(2), 536-542, Feb 2017
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THPAL068	Status of the Polarix-TDS Project	FEL, electron, undulator, status	3808
	P. Craievich, M. Bopp, H.-H. Braun, R. Ganter, T. Kleeb, M. Pedrozzi, E. Prat, S. Reiche, R. Zennaro PSI, Villigen PSI, Switzerland R.W. Aßmann, F. Christie, R.T.P. D'Arcy, U. Dorda, M. Foese, P. González Caminal, M. Hoffmann, M. Hüning, R. Jonas, O. Krebs, S. Lederer, V. Libov, B. Marchetti, D. Marx, J. Osterhoff, F. Poblotzki, M. Reukauff, H. Schlarb, S. Schreiber, G. Tews, M. Vogt, A. Wagner DESY, Hamburg, Germany N. Catalán Lasheras, A. Grudiev, G. McMonagle, W. Wuensch CERN, Geneva, Switzerland
	A collaboration between DESY, PSI and CERN has been established to develop and build an advanced modular X-band transverse deflection structure (TDS) system with the new feature of providing variable polarization of the deflecting force. This innovative CERN design requires very high manufacturing precision to guarantee highest azimuthal symmetry of the structure to avoid the deterioration of the polarization of the streaking field. Therefore, the high-precision tuning-free production process developed at PSI for the C-band and X-band accelerating structures will be used for the manufacturing. We summarize in this paper the status of the production of the prototype and the waveguide networks foreseen in the different facilities.
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THPAL073	Progress on 1.5 GHz Multi-kW CW Amplifier	operation, HOM, solenoid, insertion	3821
	A.V. Smirnov, R.B. Agustsson, S. Boucher, A.Y. Murokh, A.Yu. Smirnov RadiaBeam Systems, Santa Monica, California, USA M.A. Ahmadi, P. Blanchard, M.D. Mccann, C. Nguen, P.B. Peter, J. Zabek Microsemi Corporation, Aliso Viejo, USA G.R. Branner, K.S. Yuk UC Davis, Davis, USA J.J. Hartzell, K.J. Hoyt, T.J. Villabona RadiaBeam, Santa Monica, California, USA V. Khodos Sierra Nevada Corporation, Irvine, USA
	Funding: Work supported by the U.S. Department of Energy (award No. DE-SC0013136) JLab upgrade program foresees new CW amplifiers operating at 1497 MHz and significantly increased efficiency vs. existing VKL-7811 klystron. One of possibilities for the replacement is usage of high electron mobility packaged GaN transistors applied in array of highly efficient amplifiers using precise in-phase, low-loss combiners-dividers. We present here performance of novel, compact 300 W pallets developed at MicroSemi specifically for this project including their new GaN transistor, as well as significantly upgraded divider and combiner. Design features and challenges related to amplifier modules (pallets), broadband 21-way dividers/combiners, as well construction and assembling of the entire system are discussed including measurements.
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THPAL084	An X-Band Lineariser for the CLARA FEL	cavity, FEL, simulation, wakefield	3848
	L.S. Cowie, A.D. Brynes, J.K. Jones, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Apsimon, G. Burt, W.L. Millar Cockcroft Institute, Lancaster University, Lancaster, United Kingdom Ö. Mete UMAN, Manchester, United Kingdom A.J. Moss STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The CLARA FEL at Daresbury Laboratory will employ four S-band linacs to accelerate electron bunches to 250 MeV/c. In order to compress the bunch sufficiently to achieve peak currents suitable for FEL lasing, one must compensate for curvature imprinted on the longitudinal phase space of the bunch. For CLARA a harmonic RF linearization system has been designed to achieve this requirement. The linearization will be achieved by an X-band travelling wave cavity of the PSI/CERN design, which incorporates wake-field monitoring of the bunch position. A five-axis mover will align the cavity to the beam axis. Pulse compression of a 6 MW klystron pulse will provide the required power to achieve a 30 MV/m operational gradient.
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THPAL102	Design a High Power Pulse Transformer for C-band Klystron Modulator	flattop, high-voltage, plasma, FEL	3875
	Y.F. Liu, Z.H. Chen, M. Gu, Y. Wu, Q. Yuan, X.X. Zhou SINAP, Shanghai, People's Republic of China
	Shanghai soft X-ray Free Electron Lasers (SXFEL) first uses C band accelerator structure to accelerate electrons at SINAP. SXFEL is an X-ray free electron laser facility, which requests very stable amplitude stability and very tight tolerances of phase jitter. 50MW C-band klystron and 110MW modulator is used to provide power supply for accelerator structure. Typical specifications of the modulator are peak beam voltage 350KV, peak beam current 320A, 10Hz repetition rate, 3us flat-top pulse width. In order to meet these demands, we developed a reliable and stable high power pulse transformer. In this paper, the analysis and design of high power pulse transformer for C band klystron modulator are presented. The methods of shortening rise time, diminishing droop and diminishing flat top oscillation are highlighted. Detailed design, simulation and relevant experimental results are given. The relevant experiments show that this pulse transformer can meet the requirement of 50MW C band klystron.
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THPAL148	Status of High Efficiency Klystron Development in TETD	cavity, electron, simulation, bunching	3993
	Y. Okubo, S. Fujii, K. Suzuki, T.E. Tanaka Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
	TETD (Toshiba Electron Tubes and Devices Co., Ltd.) has been developing a high efficiency klystron improved bunch quality by the multi-stage of core oscillation design. For feasibility study, an S-band 7.5 MW klystron has been designed with the efficiency of more than 60% at 1.8μperveance. The first prototype was fabricated by modifying the interaction section of a commercial model to enhance the efficiency from 45% to 60%. The klystron was tested in June 2017, and 57% of efficiency at 6 MW output power was demonstrated. We are developing the second prototype which has the improved design for the higher efficiency at 7.5 WM output power. The design details and the test results of the first prototypes are presented.
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THPAL149	RF System Based on Two Klystrons and Phase Modulation for Photo-Cathode Injector	gun, linac, experiment, cathode	3996
	P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	We proposed an RF system with two klystrons, of which the powers are combined by a 3dB-hybrid. By managing the phases of the two klystrons respectively, the two pulses from the two output ports of the 3dB-hybrid can be of different powers, phases, and shapes. One of the two pulses can be set to an RF gun, while the other one can feed traveling accelerating structures. Two methods of phase modulation were proposed based on this scheme. Comparing with the state-of-art RF system, the new one can be of high efficiency or can generate electron beams with higher energy. The detailed analysis of the two methods and some experiments are described in this paper.
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THPAL150	Development of Tsinghua X-Band High Power Test Facility	controls, vacuum, GUI, software	3999
	M.M. Peng, D.Z. Cao, W. Gai, Y.L. Jiang, J. Liu, J. Shi, P. Wang TUB, Beijing, People's Republic of China
	The X band high power test facility consists of a 11.424 GHz, 50 MW CPI klystron and a ScandiNova pulse modulator at Tsinghua University has been built since Sept 2017 and the output RF power has reached 60 MW with 200 ns pulse width at a repetition frequency of 10. The klystron output RF pulse will eventually be 50 MW at a 1.5 μs. A group of cylinder pulse compressor will be installed. High gradient accelerating structures for research and TTX will be tested on this facility.
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THPAL153	High Power Test of the S-Band Spherical Pulse Compressor at Tsinghua University	cavity, FEL, coupling, polarization	4008
	P. Wang, D.Z. Cao, H.B. Chen, C. Cheng, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	We designed, fabricated and high power tested an S-band spherical pulse compressor for the high-power test facility at Tsinghua University. The pulse compressor comprises a spherical resonant cavity with an unloaded quality factor of 100, 000 and an RF polarizer with two rectangular ports and a circular port. To achieve high efficiency and large power gain, the coupling coefficient was optimized to 8 with input pulse length of 3.6 us and compression ratio of 12. After conditioning the RF system, the pulse compressor generated RF pulses with peak power of more than 400MW. And during the operation, the pulse compressor has very low breakdown rate and was extremely stable.
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THPAL155	Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC	cavity, operation, polarization, linear-collider	4014
	P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	A proposed RF scheme based on correction cavity chain and storage cavity (CC-SC scheme) for klystron-based CLIC has the ability to generate flat output pulses. In the scheme, the correction cavity chain modulates the amplitude of the input pulse, while the storage cavity compresses the amplitude-modulated pulse. Resonant cavities of the correction cavity chain are of a relatively low unloaded quality factor and of small size, which results in the compactness of the RF scheme. The first prototype of a correction cavity chain was fabricated and cold tested at Tsinghua University and then delivered to CERN for high power test. Both the results of the cold and high power tests show that the correction cavity chain is of good performance. Feasibility and stability of the pulse compression system based on CC-SC scheme were demonstrated.
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THPMK033	PAL-XFEL Linac RF System Status	controls, operation, electron, FEL	4369
	H.-S. Lee, Heo, J.Y. Heo, J.H. Hong, H.-S. Kang, K.H. Kim, S.H. Kim, D.H. Na, S.S. Park, Y.J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: Ministry of Science and ICT The PAL-XFEL Linear Accelerator began user support in March 2017 after one year of RF conditioning in 2016. The energy jitter was 0.013% when operating the H-X linear accelerator with 46 modulators, Klystron, LLRF, SSA and vacuum system at 6.838 GeV energy during user support period. So far, we have replaced four klystrons and 10 thyratron switches. We also measured the influence of temperature changes of RF components according to repetition rates of the machine. We will report on the measurement results of this operating experience and performance.
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THPMK058	RF Design of the X-band Linac for the EuPRAXIA@SPARC_LAB Project	linac, booster, electron, GUI	4422
	M. Diomede Sapienza University of Rome, Rome, Italy D. Alesini, M. Bellaveglia, B. Buonomo, F. Cardelli, E. Chiadroni, G. Di Raddo, R.D. Di Raddo, M. Diomede, M. Ferrario, A. Gallo, A. Ghigo, A. Giribono, V.L. Lollo, L. Piersanti, B. Spataro, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy N. Catalán Lasheras, A. Grudiev, W. Wuensch CERN, Geneva, Switzerland
	We illustrate the RF design of the X-band linac for the upgrade of the SPARC_LAB facility at INFN-LNF (EuPRAXIA@SPARC_LAB). The structures are travelling wave (TW) cavities, working on the 2π/3 mode, fed by klystrons with pulse compressor systems. The tapering of the cells along the structure and the cell profiles have been optimized to maximize the effective shunt impedance keeping under control the maximum value of the modified Poynting vector, while the couplers have been designed to have a symmetric feeding and a reduced pulsed heating. In the paper we also present the RF power distribution layout of the accelerating module and a preliminary mechanical design.
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THPMK064	RF System for SXFEL: C-band, X-band and S-band	FEL, linac, operation, LLRF	4446
	W. Fang, Q. Gu, X.X. Huang, L. Li, Z.B. Li, J.H. Tan, C.C. Xiao, J.Q. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	Shanghai Soft X-ray FEL facility is under commissioning now, which linac is compased of one S-band injector, C-band main linac and X-band linearizer. In SXFEL S-band injector could provide 200MeV beam energy based on 4 RF power unit, and then 6 C-band RF units boost beam energy to 840MeV based on 33MV/m at least, which will be ramped to 40MV/m in the ungrading. In the middle of S-band and C-band RF system, a X-band RF unit is used as linearizer to make energy spread of electron beam linear distribution, which is important for bunch compressor and FEL radiation. In this paper, details of RF system design and status of SXFEL is introduced, and some operation results are presented.
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THPMK104	High Power and High Repetition Rate X-band Power Source Using Multiple Klystrons	controls, GUI, MMI, network	4552
	M. Volpi, M.J. Boland, P.J. Giansiracusa, T.G. Lucas, R.P. Rassool The University of Melbourne, Melbourne, Victoria, Australia N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano CERN, Geneva, Switzerland J. Paszkiewicz University of Oxford, Oxford, United Kingdom C. Serpico Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy A. Vnuchenko IFIC, Valencia, Spain
	In July 2016, the first X-band test facility operating with two interwoven, 6 MW klystron pulses was commissioned at CERN. Outputting up to 46 MW after pulse compression, the new test stand allows testing of two structures concurrently with repetition rates up to 400 Hz in each line. RF commissioning of all four lines has been completed and testing of high gradient accelerating structures for the Compact Linear Collider has commenced. Operations have been ongoing for more than a year, where dedicated control algorithms have been developed to conditioning the structure and to keep the pulse compressors tuned. Significant progress has been made in understanding the conditioning of two structures that are sharing an interlock and vacuum system. The high repetition rate is already showing the significantly reduced time needed to condition accelerating structures.
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THPML073	Measurement of the RF Reference Phase Stability in the SuperKEKB Injector LINAC	linac, controls, feedback, booster	4815
	N. Liu Sokendai, Ibaraki, Japan D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, F. Qiu, Y. Yano KEK, Ibaraki, Japan
	The SuperKEKB injector is a more than 600 m J-shaped LINAC. The requirement of the RF phase refer-ence stability is 0.1 degree (RMS) at 2856 MHz for SuperKEKB PHASE-2 commissioning. In order to clari-fy and improve the reference line performance, the RF reference phase stability is measured. The phase noise of the RF reference at each sector is shown in this paper. A new phase monitor system is implemented to measure the short-term stability and long-term drift due to the temperature and humidity fluctuations in the klystron gallery.
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Paper

Title

Other Keywords

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MOYGB1

Status and Future Strategy for Advanced High Power Microwave Sources for Accelerators

electron, cavity, operation, linac

12

F. Gerigk
CERN, Geneva, Switzerland

The need for more energy efficient high power microwave devices for accelerator applications continues to increase. This is important for development of cost effective accelerator designs that are coming up in the near future. Efforts are already in place to design new devices that could stretch the limits of RF power conversion to the highest levels possible. Devices including new technologies and design innovations like multi beam, increased number of cavities designs are being considered. Advances in the application of solid state amplifiers to accelerators are also being realized. This invited talk will cover the recent advances and status of such efforts. It will discuss future needs and a strategy for pursuing these efforts on a faster time scale for the benefit of the accelerator community.

Slides MOYGB1 [11.575 MB]

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TUPAF017

Stability Analysis of the TOP-IMPLART 35 MeV Proton Beam

DTL, linac, proton, booster

697

P. Nenzi, A. Ampollini, G. Bazzano, L. Picardi, C. Ronsivalle, V. Surrenti, E. Trinca, M. Vadrucci
ENEA C.R. Frascati, Frascati (Roma), Italy

Funding: The TOP-IMPLART program is funded by Regione Lazio.
The TOP-IMPLART (Intensity Modulated Proton Linear Accelerator for RadioTherapy) is the demonstrator of a 150 MeV proton linear accelerator devoted to cancer treatment application under development at ENEA-Frascati. It is a full linear machine composed by a 425 MHz 7 MeV injector and a high frequency linac operating at 2997.92 MHz. The first accelerating section, installed and in operation, consists of 4 SCDTL structures and delivers a 35 MeV beam in 3 microseconds pulses at a maximum repetition frequency of 50 Hz. The principal advantage of a linear accelerator, in a therapeutic application, is the quick setting possibility (up to pulse-to-pulse, in principle) of the physical properties of the proton beam, offering larger flexibility (compared to traditional circular designs) and improved precision on dose delivery to the patient., The short and long range stability of the machine have been analyzed measuring on a pulse by pulse basis both the output beam characteristics and other machine parameters in order to identify those that mainly affect the beam stability. This work describes the methodology used in this study, the main results achieved and the future developments.

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TUZGBF5

KlyLac Prototyping for Borehole Logging

linac, cavity, feedback, simulation

1244

A.V. Smirnov, R.B. Agustsson, M.A. Harrison, A.Y. Murokh, A.Yu. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
S. Boucher, T.J. Campese, K.J. Hoyt
RadiaBeam, Los Angeles, California, USA
E.A. Savin
MEPhI, Moscow, Russia
A.A. Zavadtsev
Nano, Moscow, Russia

Funding: Work supported by the U.S. Department of Energy (award No. DE-SC0015721)
Linac-based system for borehole logging exploits KlyLac approach combing klystron and linac sharing the same electron beam, vacuum volume, and RF network enabling self-oscillation due to a positive feedback. The KlyLac prototype design tailors delivering ~1 MeV electrons in a linac section using part of the beam injected from a sheet beam klystron (SBK). The linac part is based on a very robust, high group velocity, cm-wave, and a standing wave accelerating structure of a 'cross-pin' type supplied by a sampler. The SBK part features a permanent magnet solenoid focusing, relatively low voltage, and high aspect ratio beam. The main SBK characteristics (perveance, power, and efficiency) are expected to be similar to that for a magnetron.

Slides TUZGBF5 [3.280 MB]

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TUPMF037

Development of New Operational Mode for NSLS-II Injector: Low Energy 100MeV Linac-to-Booster Injection

booster, injection, operation, linac

1330

X. Yang, A.A. Derbenev, R.P. Fliller, T.V. Shaftan, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

The NSLS-II injector consists of a 200 MeV linac and a 3 GeV full-energy booster synchrotron. The linac contains five traveling-wave S-band accelerating structures driven by two high-power klystrons, with a third klystron as spare. In the event that the spare klystron is not available, the failure of one klystron will prohibit the linac from injecting into the booster as the energy is too low. Therefore, we wish to develop a new operational mode that the NSLS-II injector can operate with a single klystron providing 100 MeV beam from the linac. A decremented approach with intermediate energies 170 MeV, 150 MeV, etc., takes advantages of pre-calculated booster ramps and beam based online optimization. By lowering the booster injection energy in a small step and online optimizing at each step, we were able to achieve 100 MeV booster injection. 170 MeV operation mode of the NSLS-II injector has been implemented since May 31, 2017, with a similar overall performance compared to the standard 200 MeV operation but fewer klystron trips. 100 MeV single-klystron operation has been successfully demonstrated with 20-30% overall efficiency, which is limited by booster acceptance.

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WEXGBF1

Testing of the ESS MB-IOT Prototypes

linac, cavity, operation, electron

1759

M. Jensen
ESS, Lund, Sweden
C. Bel, A. Beunas, D. Bussiere, P. Cacheux, V. Hermann, J.C. Racamier, C. Robert
TED, Thonon, France
M. Boyle, H. Schult
L-3, Williamsport, Pennsylvania, USA
G. Cipolla, E. Montesinos, M.S.B. Sanchez Barrueta
CERN, Geneva 23, Switzerland
T. Kimura, P.E. Kolda, P. Krzeminski, L. Kurek, S. Lenci, O.S. Sablic, L. Turek, C. Yates
CPI, Palo Alto, California, USA
M.F. Kirshner
LANL, Los Alamos, New Mexico, USA
R.D. Kowalczyk, A.V. Sy, B.R. Weatherford
SLAC, Menlo Park, California, USA
A. Zubyk
L3 EDD, Williamsport, USA

ESS is considering the use of MB-IOTs for parts of the high-beta linac. Two prototypes have been built by indus-try, namely L3 and CPI/Thales and have passed the factory acceptance test with excellent results. Both tubes will go through further extensive testing at CERN for ESS follow-ing delivery and a final decision on tube technology will be taken in April 2018. This invited talk presents the back-ground for the technical decision of IOTs vs klystrons, associated impact for ESS, and latest plans for industrial production of these IOTs for ESS.

Slides WEXGBF1 [9.836 MB]

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WEPAF022

Application of Machine Learning to Minimize Long Term Drifts in the NSLS-II Linac

linac, network, operation, booster

1867

R.P. Fliller, C. Gardner, P. Marino, R.S. Rainer, M. Santana, G.J. Weiner, X. Yang, E. Zeitler
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
Machine Learning has proven itself as a useful technique in a variety of applications from image recognition to playing Go. Artificial Neural Networks have certain advantages when used as a feedforward system, such as the predicted correction relies on a model built from data. This allows for the Artificial Neural Network to compensate for effects that are difficult to model such as low level RF adjustments to compensate for long term drifts. The NSLS-II linac suffers from long terms drifts from a number of sources including thermal drifts and klystron gain variations. These drifts have an effect on the injection efficiency into the booster, and if left unchecked, portions of the bunch train may not be injected into the booster, and the storage ring bunch pattern will ultimately suffer. In this paper, we discuss the application of Artificial Neural Networks to compensate for long term drifts in the NSLS-II linear accelerator. The Artificial Neural Network is implemented in python allowing for rapid development of the network. We discuss the design and training of the network, along with results of using the network in operation.

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WEPAF076

Availability Studies Comparing Drive Beam and Klystron Options for the Compact Linear Collider

operation, simulation, linac, software

2013

O. Rey Orozko, S. Döbert, M. Jonker
CERN, Geneva, Switzerland

The initial proposal for the Compact Linear Collider (CLIC) is based on a two beam-scheme to accelerate the main colliding beams. For low collision energies, the main beam could also be accelerated by powering the accelerating structures with klystrons instead of the two-beam scheme. This paper studies the feasibility of this new alternative in terms of machine availability. An implemented bottom-up availability model considers the components failure modes to estimate the overall availability of the system. The model is defined within a Common Input Format scheme and the AvailSim3 software package is used for availability simulations. This paper gives an overview of the systems affecting the beam powering availability and makes recommendations for availability improvements.

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WEPAK018

LLRF Control Unit for SuperKEKB Injector Linac

controls, LLRF, linac, timing

2134

T. Miura, M. Akemoto, D.A. Arakawa, H. Katagiri, T. Matsumoto, F. Qiu, Y. Yano
KEK, Ibaraki, Japan
N. Liu
Sokendai, Ibaraki, Japan

The low-level RF (LLRF) control unit based on the digital system has been developed for a stable and high precision pulse modulation for the SuperKEKB. The RF pulse is changed at a 50-Hz repetition rate for the top-up injection to four different rings by the event system. The LLRF control unit has not only the pulse modulator, but also other functions: VSWR meter, RF monitor, event receiver (EVR), and pulse-shortening detection.

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WEPAL022

Operating Experience of Water Cooling System in the J-PARC LINAC and RCS

linac, acceleration, diagnostics, DTL

2203

K. Suganuma, K. Fujirai, M. Kinsho, P.K. Saha, Y. Yamazaki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The cooling system for the J-PARC LINAC and RCS uses a total of 25 circulation pumps to cool the accelerator devices. In February 2017, we experienced damage of circulation pumps due to low flow rate, and started the development of an abnormality detection system concentrating on the vibration measurements of the circulation pumps. In this report, the vibration measurement results of the coolant circulation pumps and the development status of abnormality detection through multivariate analysis using vibration values are discussed.

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WEPAL023

Pulsed Operation at MAMI with High Beam Loading

experiment, beam-losses, operation, beam-loading

2206

M. Dehn, K. Aulenbacher, F. Fichtner, P. Jennewein, W. Klag, H.-J. Kreidel, J.R. Röthgen
IKP, Mainz, Germany

Funding: Work supported by DFG (CRC 1044) and the German federal state of Rhineland-Palatinate
The Mainz Microtron Accelerator (MAMI) is a microtron cascade which is normally operated CW for particle physics experiments. For certain investigations it is necessary to use a pulsed beam (macro pulses, several milliseconds). Up to now this pulsed mode can only be applied if the beam loading for the accelerating RF structures is negligible. To achieve higher pulse intensities the accelerator RF infrastructure needs to be equipped with feed-forward techniques to compensate for the expected beam loading. To monitor beam losses the machine protection system at MAMI needs to be extended to be able to localize fast occurrences of beam losses. This paper will present the possibilities being investigated to allow pulsed operation of MAMI within the near future.

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WEPMF030

Optimization of Klystron Efficiency with MOGA

cavity, electron, simulation, bunching

2419

C. Meng, X. He, S. Pei, S.C. Wang, O. Xiao, Z.S. Zhou
IHEP, Beijing, People's Republic of China

As the very important element of accelerator the klystron provide power to cavities for accelerating. Considering the accelerator cost of construction and running, the improvement of klystron efficiency is one developing hotspot of klystron research. In this paper the optimization method of klystron efficiency with MOGA based on 1D simulation program is proposed and the influences on klystron efficiency will be discussed.

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WEPMF033

RF Study And Cold Test of an S-band Spherical Cavity Pulse Compressor

cavity, coupling, simulation, vacuum

2429

J. Lei, X. He, M. Hou, X.P. Li, G. Pei, H. Wang, J.B. Zhao
IHEP, Beijing, People's Republic of China
S. Shu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

An S-band (2856 MHz) spherical cavity pulse compressor has been designed, fabricated and tested in the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS). The pulse compressor consists of a special 3 dB coupler and only one spherical energy storage cavity, two TE114 modes are chosen to oscillate in which for fairly high unload Q factor. The prototype was made of aluminum for studying the performance of the pulse compressor and checking the validity of the simulations. The cold test results of the aluminum cavity are also presented. The copper coating on the whole internal surface of the aluminum spherical cavity is in progress and the test results will also be presented in the future.

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WEPMF053

XFEL Modulators with Pulse Cables

FEL, operation, linac, radiation

2487

H.-J. Eckoldt, S. Choroba, T. Grevsmühl, A. Hauberg, J. Havlicek, N. Heidbrook, K. Machau, N. Ngada
DESY, Hamburg, Germany
M. Frei, S.G. Keens, T.H. Strittmatter
Ampegon AG, Turgi, Switzerland
H. Leich
DESY Zeuthen, Zeuthen, Germany

The modulators of the European XFEL produce high voltage, at the 10kV level, having a power of up to 16.8 MW for 1.54 ms. The operation frequency of the super-conducting inac is 10 Hz. The series production of the 29 modulators started in 2012. The first modulator began operation in 2014 and the start of linac was beginning 2017. The R&D phase for the modulators started directly with the development of superconducting cavities. Besides the pulse generation, the modulator had to suppress the 10 Hz repetition rate in order not to disturb the grid. Another unique demand was the development of pulse cables. Since the power RF had to be generated in the tunnel, the klystrons were installed near the cavities. However, the modulators had to be installed outside of the tunnel for space, maintenance reasons and radiation concerns. This transmission of high power pulses via long cables is unique in the world and the suppression of EMI effects was mandatory. During the first year operation no EMI disturbances of other systems were detected and the modulator system works as expected.

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WEPMF063

Thyratron Replacement*

operation, high-voltage, linear-collider, collider

2512

I. Roth, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: Funded under US DOE grant no. DE-SC0011292.
Thyratrons are typically used as the switch in high power, short pulse modulators with pulse-forming networks. However, thyratrons have a lifetime of only ten to twenty thousand hours, their reservoir heater voltage needs to be adjusted periodically, and reduced overall demand has led multiple thyratron vendors to slow or cease production. In contrast, solid-state switches have a much longer lifetime, need no maintenance, and are based on widely-available commercial items. Despite these advantages, solid-state devices have not historically seen use, due to limited voltage, current, and risetime. Diversified Technologies, Inc. (DTI) has removed this barrier, having developed, built, and tested a thyratron-replacement switch for SLAC based on an array of series and parallel-connected commercial insulated-gate bipolar transistors (IGBTs). This switch has demonstrated operation at very high voltage and current, meeting the full specifications required by SLAC to completely replace (form-fit-function-interface) the L-4888 thyratron: 48 kV, 6.3 kA, and 1 μs risetime.

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WEPMF064

Daresbury Laboratory Short Pulse Klystron Modulators

high-voltage, operation, power-supply, factory

2515

C. Chipman, M.P.J. Gaudreau, L. Jashari, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA
S.A. Griffiths, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.J. Zhang
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China

Diversified Technologies, Inc. (DTI) has developed a unique short pulse klystron modulator system for the Compact Linear Advanced Research Accelerator (CLARA) Project at Daresbury Laboratory. One unit has been delivered and three more are on contract. This system is based on the combination of a high voltage solid-state switch, with a conventional 1:7 pulse transformer, and a passive pulse corrector with automated adjustment. This unique passive circuitry delivers the extremely flat output pulse required for advanced accelerator applications. The CLARA modulators share design elements with previous DTI modulators which provides both a lower cost and easier to maintain system. The modulators are designed to pulse 80 MW-class klystrons at an avg power of 250 kW and provides adjustable high efficiency operation in the 45 kV to 450 kV range for currents up to 545 A and pulse lengths of 1.5 to 4.0 μs. One key objective of modulator development is optimization of voltage flatness (± 0.02 %), stability (± 0.05 %), and reproducibility (± 0.05 %).

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THPAL005

Construction and Commissioning of the S-Band High-Gradient RF Laboratory at IFIC

network, GUI, linac, cathode

3619

D. Esperante Pereira, C. Blanch Gutiérrez, M. Boronat, J. Fuster, D. Gonzalez Iglesias, A. Vnuchenko
IFIC, Valencia, Spain
N. Catalán Lasheras, G. McMonagle, I. Syratchev, W. Wuensch
CERN, Geneva, Switzerland
A. Faus-Golfe
LAL, Orsay, France
B. Gimeno
UVEG, Burjasot (Valencia), Spain

An S-Band High-Gradient (HG) Radio Frequency (RF) laboratory is under construction and commissioning at IFIC. The purpose of the laboratory is to perform investigations of high-gradient phenomena and to develop normal-conducting RF technology, with special focus on RF systems for hadron-therapy. The layout of the facility is derived from the scheme of the Xbox-3 test facility at CERN* and uses medium peak-power (7.5 MW) and high repetition rate (400 Hz) klystrons, whose RF output is combined to drive two testing slots to the required power. The design and construction of the various components of the system started in 2016 and has been completed. The installation and commissioning of the laboratory is progressing, with first results expected before mid 2018. The technical characteristics of the different elements of the system and the commissioning status together with preliminary results are described.
* N. Catalan Lasheras, et al., 'Commissioning of Xbox3: a very high capacity X-band RF test stand', Proc. LINAC2016, East Lansing, USA, September 2016.

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THPAL027

Transverse RF Deflecting Structures for the MAX IV LINAC

GUI, linac, polarization, emittance

3684

D. Olsson, F. Curbis, E. Mansten, S. Thorin, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). A soft X-ray Laser (SXL) beamline will also be installed in the end of the existing LINAC. For SPF and SXL operation, it is important to characterize beam parameters such as bunch profile, slice energy spread and slice emittance. For these measurements, two 3 m long transverse deflecting RF structures with a matching section are being developed. The structures are operating at S-band and have variable polarizations. When fed via a SLED pulse compressor, the two structures can generate a total integrated deflecting voltage higher than 100 MV which is sufficient for measurements with temporal resolutions down to 1 fs. This paper describes the initial RF design of the deflecting structures.

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THPAL053

Perveance Measurement of the TLS-Linac Klystron and the Evaluation of Its Operation Performance

electron, operation, cathode, linac

3763

H.H. Chen, C.H. Kuo, K.-K. Lin, Y.-H. Liu
NSRRC, Hsinchu, Taiwan

The high power klystron is a radio frequency amplifier for TLS linac operation. It is a crucial device for electron acceleration in linac. How to evaluate its efficiency, lifetime and performance of klystron in operation is one of the major concern in this report. The key klystron parameter perveance is introduced and used for performance evaluation and operation status monitoring. It is important to execute periodic monitoring on perveance for ensuring a stable linac operation. Klystron characteristics diagnostics can be achieved through perveance measurement. A couple of klystron diagnostic parameters concerning perveance are explored for field examination purpose. Perveance comparison with factory acceptance test data is also presented.

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THPAL060

Advanced Modeling of Klystrons by the Tesla-Family of Large-Signal Codes

cavity, impedance, experiment, simulation

3785

I.A. Chernyavskiy, D.K. Abe, B. Levush, A.N. Vlasov
NRL, Washington, DC, USA
T.M. Antonsen
UMD, College Park, Maryland, USA
T.M. Antonsen
Leidos Corp, Billerica, MA, USA
J. Rodgers
Naval Research Laboratory (NRL), Washington, USA

Funding: US Office of the Naval Research
Klystrons and IOTs are widely used or proposed to be used in accelerators as high-power RF sources. Development and optimization of klystron and IOT designs is aided by the use of different simulation tools, including highly efficient large-signal codes. We present an overview of the advances in the code development and modeling using Naval Research Laboratory (NRL) set of TESLA-family of large-signal codes, suitable for the modeling of single-beam and multiple beam klystrons and IOTs. Original 2D large-signal algorithm of the code TESLA* was developed for the modeling of klystrons based on (relatively) high Q resonators and is applicable to the multiple-beam devices in an approximation of identical beams/beam-tunnels. Parallel extension of TESLA algorithm (code TESLA-MB**) enabled an accurate, quasi-3D modeling of multiple-beam devices with non-identical beams/beam-tunnels. Recently developed more general TESLA-Z algorithm*** is based on the impedance matrix approach and enabled geometry-driven large-signal modeling. Examples of applications of TESLA-family of codes to the modeling of advanced single-beam and multiple-beam klystrons (and IOTs) will be presented.
*A.N. Vlasov, et al,IEEE TPS, v.30(3), 1277-1291, June 2002
**I.A. Chernyavskiy, et al.,IEEE TPS, v.36(3), 670-681, June 2008
***I.A. Chernyavskiy, et al.,IEEE TED, v.64(2), 536-542, Feb 2017

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THPAL068

Status of the Polarix-TDS Project

FEL, electron, undulator, status

3808

P. Craievich, M. Bopp, H.-H. Braun, R. Ganter, T. Kleeb, M. Pedrozzi, E. Prat, S. Reiche, R. Zennaro
PSI, Villigen PSI, Switzerland
R.W. Aßmann, F. Christie, R.T.P. D'Arcy, U. Dorda, M. Foese, P. González Caminal, M. Hoffmann, M. Hüning, R. Jonas, O. Krebs, S. Lederer, V. Libov, B. Marchetti, D. Marx, J. Osterhoff, F. Poblotzki, M. Reukauff, H. Schlarb, S. Schreiber, G. Tews, M. Vogt, A. Wagner
DESY, Hamburg, Germany
N. Catalán Lasheras, A. Grudiev, G. McMonagle, W. Wuensch
CERN, Geneva, Switzerland

A collaboration between DESY, PSI and CERN has been established to develop and build an advanced modular X-band transverse deflection structure (TDS) system with the new feature of providing variable polarization of the deflecting force. This innovative CERN design requires very high manufacturing precision to guarantee highest azimuthal symmetry of the structure to avoid the deterioration of the polarization of the streaking field. Therefore, the high-precision tuning-free production process developed at PSI for the C-band and X-band accelerating structures will be used for the manufacturing. We summarize in this paper the status of the production of the prototype and the waveguide networks foreseen in the different facilities.

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THPAL073

Progress on 1.5 GHz Multi-kW CW Amplifier

operation, HOM, solenoid, insertion

3821

A.V. Smirnov, R.B. Agustsson, S. Boucher, A.Y. Murokh, A.Yu. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
M.A. Ahmadi, P. Blanchard, M.D. Mccann, C. Nguen, P.B. Peter, J. Zabek
Microsemi Corporation, Aliso Viejo, USA
G.R. Branner, K.S. Yuk
UC Davis, Davis, USA
J.J. Hartzell, K.J. Hoyt, T.J. Villabona
RadiaBeam, Santa Monica, California, USA
V. Khodos
Sierra Nevada Corporation, Irvine, USA

Funding: Work supported by the U.S. Department of Energy (award No. DE-SC0013136)
JLab upgrade program foresees new CW amplifiers operating at 1497 MHz and significantly increased efficiency vs. existing VKL-7811 klystron. One of possibilities for the replacement is usage of high electron mobility packaged GaN transistors applied in array of highly efficient amplifiers using precise in-phase, low-loss combiners-dividers. We present here performance of novel, compact 300 W pallets developed at MicroSemi specifically for this project including their new GaN transistor, as well as significantly upgraded divider and combiner. Design features and challenges related to amplifier modules (pallets), broadband 21-way dividers/combiners, as well construction and assembling of the entire system are discussed including measurements.

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THPAL084

An X-Band Lineariser for the CLARA FEL

cavity, FEL, simulation, wakefield

3848

L.S. Cowie, A.D. Brynes, J.K. Jones, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Apsimon, G. Burt, W.L. Millar
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
Ö. Mete
UMAN, Manchester, United Kingdom
A.J. Moss
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The CLARA FEL at Daresbury Laboratory will employ four S-band linacs to accelerate electron bunches to 250 MeV/c. In order to compress the bunch sufficiently to achieve peak currents suitable for FEL lasing, one must compensate for curvature imprinted on the longitudinal phase space of the bunch. For CLARA a harmonic RF linearization system has been designed to achieve this requirement. The linearization will be achieved by an X-band travelling wave cavity of the PSI/CERN design, which incorporates wake-field monitoring of the bunch position. A five-axis mover will align the cavity to the beam axis. Pulse compression of a 6 MW klystron pulse will provide the required power to achieve a 30 MV/m operational gradient.

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THPAL102

Design a High Power Pulse Transformer for C-band Klystron Modulator

flattop, high-voltage, plasma, FEL

3875

Y.F. Liu, Z.H. Chen, M. Gu, Y. Wu, Q. Yuan, X.X. Zhou
SINAP, Shanghai, People's Republic of China

Shanghai soft X-ray Free Electron Lasers (SXFEL) first uses C band accelerator structure to accelerate electrons at SINAP. SXFEL is an X-ray free electron laser facility, which requests very stable amplitude stability and very tight tolerances of phase jitter. 50MW C-band klystron and 110MW modulator is used to provide power supply for accelerator structure. Typical specifications of the modulator are peak beam voltage 350KV, peak beam current 320A, 10Hz repetition rate, 3us flat-top pulse width. In order to meet these demands, we developed a reliable and stable high power pulse transformer. In this paper, the analysis and design of high power pulse transformer for C band klystron modulator are presented. The methods of shortening rise time, diminishing droop and diminishing flat top oscillation are highlighted. Detailed design, simulation and relevant experimental results are given. The relevant experiments show that this pulse transformer can meet the requirement of 50MW C band klystron.

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THPAL148

Status of High Efficiency Klystron Development in TETD

cavity, electron, simulation, bunching

3993

Y. Okubo, S. Fujii, K. Suzuki, T.E. Tanaka
Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan

TETD (Toshiba Electron Tubes and Devices Co., Ltd.) has been developing a high efficiency klystron improved bunch quality by the multi-stage of core oscillation design. For feasibility study, an S-band 7.5 MW klystron has been designed with the efficiency of more than 60% at 1.8μperveance. The first prototype was fabricated by modifying the interaction section of a commercial model to enhance the efficiency from 45% to 60%. The klystron was tested in June 2017, and 57% of efficiency at 6 MW output power was demonstrated. We are developing the second prototype which has the improved design for the higher efficiency at 7.5 WM output power. The design details and the test results of the first prototypes are presented.

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THPAL149

RF System Based on Two Klystrons and Phase Modulation for Photo-Cathode Injector

gun, linac, experiment, cathode

3996

P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

We proposed an RF system with two klystrons, of which the powers are combined by a 3dB-hybrid. By managing the phases of the two klystrons respectively, the two pulses from the two output ports of the 3dB-hybrid can be of different powers, phases, and shapes. One of the two pulses can be set to an RF gun, while the other one can feed traveling accelerating structures. Two methods of phase modulation were proposed based on this scheme. Comparing with the state-of-art RF system, the new one can be of high efficiency or can generate electron beams with higher energy. The detailed analysis of the two methods and some experiments are described in this paper.

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THPAL150

Development of Tsinghua X-Band High Power Test Facility

controls, vacuum, GUI, software

3999

M.M. Peng, D.Z. Cao, W. Gai, Y.L. Jiang, J. Liu, J. Shi, P. Wang
TUB, Beijing, People's Republic of China

The X band high power test facility consists of a 11.424 GHz, 50 MW CPI klystron and a ScandiNova pulse modulator at Tsinghua University has been built since Sept 2017 and the output RF power has reached 60 MW with 200 ns pulse width at a repetition frequency of 10. The klystron output RF pulse will eventually be 50 MW at a 1.5 μs. A group of cylinder pulse compressor will be installed. High gradient accelerating structures for research and TTX will be tested on this facility.

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THPAL153

High Power Test of the S-Band Spherical Pulse Compressor at Tsinghua University

cavity, FEL, coupling, polarization

4008

P. Wang, D.Z. Cao, H.B. Chen, C. Cheng, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

We designed, fabricated and high power tested an S-band spherical pulse compressor for the high-power test facility at Tsinghua University. The pulse compressor comprises a spherical resonant cavity with an unloaded quality factor of 100, 000 and an RF polarizer with two rectangular ports and a circular port. To achieve high efficiency and large power gain, the coupling coefficient was optimized to 8 with input pulse length of 3.6 us and compression ratio of 12. After conditioning the RF system, the pulse compressor generated RF pulses with peak power of more than 400MW. And during the operation, the pulse compressor has very low breakdown rate and was extremely stable.

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THPAL155

Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC

cavity, operation, polarization, linear-collider

4014

P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

A proposed RF scheme based on correction cavity chain and storage cavity (CC-SC scheme) for klystron-based CLIC has the ability to generate flat output pulses. In the scheme, the correction cavity chain modulates the amplitude of the input pulse, while the storage cavity compresses the amplitude-modulated pulse. Resonant cavities of the correction cavity chain are of a relatively low unloaded quality factor and of small size, which results in the compactness of the RF scheme. The first prototype of a correction cavity chain was fabricated and cold tested at Tsinghua University and then delivered to CERN for high power test. Both the results of the cold and high power tests show that the correction cavity chain is of good performance. Feasibility and stability of the pulse compression system based on CC-SC scheme were demonstrated.

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THPMK033

PAL-XFEL Linac RF System Status

controls, operation, electron, FEL

4369

H.-S. Lee, Heo, J.Y. Heo, J.H. Hong, H.-S. Kang, K.H. Kim, S.H. Kim, D.H. Na, S.S. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: Ministry of Science and ICT
The PAL-XFEL Linear Accelerator began user support in March 2017 after one year of RF conditioning in 2016. The energy jitter was 0.013% when operating the H-X linear accelerator with 46 modulators, Klystron, LLRF, SSA and vacuum system at 6.838 GeV energy during user support period. So far, we have replaced four klystrons and 10 thyratron switches. We also measured the influence of temperature changes of RF components according to repetition rates of the machine. We will report on the measurement results of this operating experience and performance.

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THPMK058

RF Design of the X-band Linac for the EuPRAXIA@SPARC_LAB Project

linac, booster, electron, GUI

4422

M. Diomede
Sapienza University of Rome, Rome, Italy
D. Alesini, M. Bellaveglia, B. Buonomo, F. Cardelli, E. Chiadroni, G. Di Raddo, R.D. Di Raddo, M. Diomede, M. Ferrario, A. Gallo, A. Ghigo, A. Giribono, V.L. Lollo, L. Piersanti, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
N. Catalán Lasheras, A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland

We illustrate the RF design of the X-band linac for the upgrade of the SPARC_LAB facility at INFN-LNF (EuPRAXIA@SPARC_LAB). The structures are travelling wave (TW) cavities, working on the 2π/3 mode, fed by klystrons with pulse compressor systems. The tapering of the cells along the structure and the cell profiles have been optimized to maximize the effective shunt impedance keeping under control the maximum value of the modified Poynting vector, while the couplers have been designed to have a symmetric feeding and a reduced pulsed heating. In the paper we also present the RF power distribution layout of the accelerating module and a preliminary mechanical design.

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THPMK064

RF System for SXFEL: C-band, X-band and S-band

FEL, linac, operation, LLRF

4446

W. Fang, Q. Gu, X.X. Huang, L. Li, Z.B. Li, J.H. Tan, C.C. Xiao, J.Q. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Shanghai Soft X-ray FEL facility is under commissioning now, which linac is compased of one S-band injector, C-band main linac and X-band linearizer. In SXFEL S-band injector could provide 200MeV beam energy based on 4 RF power unit, and then 6 C-band RF units boost beam energy to 840MeV based on 33MV/m at least, which will be ramped to 40MV/m in the ungrading. In the middle of S-band and C-band RF system, a X-band RF unit is used as linearizer to make energy spread of electron beam linear distribution, which is important for bunch compressor and FEL radiation. In this paper, details of RF system design and status of SXFEL is introduced, and some operation results are presented.

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THPMK104

High Power and High Repetition Rate X-band Power Source Using Multiple Klystrons

controls, GUI, MMI, network

4552

M. Volpi, M.J. Boland, P.J. Giansiracusa, T.G. Lucas, R.P. Rassool
The University of Melbourne, Melbourne, Victoria, Australia
N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano
CERN, Geneva, Switzerland
J. Paszkiewicz
University of Oxford, Oxford, United Kingdom
C. Serpico
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Vnuchenko
IFIC, Valencia, Spain

In July 2016, the first X-band test facility operating with two interwoven, 6 MW klystron pulses was commissioned at CERN. Outputting up to 46 MW after pulse compression, the new test stand allows testing of two structures concurrently with repetition rates up to 400 Hz in each line. RF commissioning of all four lines has been completed and testing of high gradient accelerating structures for the Compact Linear Collider has commenced. Operations have been ongoing for more than a year, where dedicated control algorithms have been developed to conditioning the structure and to keep the pulse compressors tuned. Significant progress has been made in understanding the conditioning of two structures that are sharing an interlock and vacuum system. The high repetition rate is already showing the significantly reduced time needed to condition accelerating structures.

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THPML073

Measurement of the RF Reference Phase Stability in the SuperKEKB Injector LINAC

linac, controls, feedback, booster

4815

N. Liu
Sokendai, Ibaraki, Japan
D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura, F. Qiu, Y. Yano
KEK, Ibaraki, Japan

The SuperKEKB injector is a more than 600 m J-shaped LINAC. The requirement of the RF phase refer-ence stability is 0.1 degree (RMS) at 2856 MHz for SuperKEKB PHASE-2 commissioning. In order to clari-fy and improve the reference line performance, the RF reference phase stability is measured. The phase noise of the RF reference at each sector is shown in this paper. A new phase monitor system is implemented to measure the short-term stability and long-term drift due to the temperature and humidity fluctuations in the klystron gallery.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML073

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