2011 Particle Accelerator Conference - List of Keywords (klystron)

Paper	Title	Other Keywords	Page
MOP012	Ultra-High Gradient Compact S-Band Accelerating Structure	coupling, linac, vacuum, simulation	127
	L. Faillace, R.B. Agustsson, P. Frigola, A.Y. Murokh RadiaBeam, Santa Monica, USA V.A. Dolgashev SLAC, Menlo Park, California, USA J.B. Rosenzweig UCLA, Los Angeles, California, USA V. Yakimenko BNL, Upton, Long Island, New York, USA
	Funding: Dept. of Energy DE-SC0000866 In this paper, we present the radio-frequency design of the DECA (Doubled Energy Compact Accelerator) S-band accelerating structure operating in the pi-mode at 2.856 GHz, where RF power sources are commonly available. The development of the DECA structure will offer an ultra-compact drop-in replacement for a conventional S-band linac in research and industrial applications such as drivers for compact light sources, medical and security systems. The electromagnetic design has been performed with the codes SuperFish and HFSS. The choice of the single cell shape derives from an optimization process aiming to maximize RF efficiency and minimize surface fields at very high accelerating gradients, i.e. 50 MV/m and above. Such gradients can be achieved utilizing shape-optimized elliptical irises, dual-feed couplers with the "fat-lip" coupling slot geometry, and specialized fabrication procedures developed for high gradient structures. The thermal-stress analysis of the DECA structure is also presented. * V. Dolgashev, "Status of X-band Standing Wave Structure Studies at SLAC", SLAC-PUB-10124, (2003). ** C. Limborg et al., "RF Design of LCLS Gun", LCLS-TN-05-03 (2005).

MOP144	Multi-Harmonic Cavity for RF Breakdown Studies	cavity, acceleration, cathode, electron	361
	Y. Jiang Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA J.L. Hirshfield Yale University, Physics Department, New Haven, CT, USA S. Kazakov, S.V. Kuzikov Omega-P, Inc., New Haven, Connecticut, USA
	Funding: DOE, Office of HEP An axially-asymmetric cavity to support several modes at harmonically-related frequencies is predicted to sustain higher RF breakdown thresholds than a conventional pillbox cavity, when driven by two or more external RF phase-locked harmonic sources. Experimental efforts are underway at Yale Beam Physics Lab to study RF breakdown in a bimodal asymmetric cavity. Such a cavity could be a basic building-block for a future high-gradient warm accelerator structure. * S.Yu. Kazakov, S.V. Kuzikov, Y. Jiang, and J.L. Hirshfield, PRSTAB, 13, 071303 (2010). ** S.V. Kuzikov, S.Yu. Kazakov, Y. Jiang, and J.L. Hirshfield, PRL 104, 214801 (2010).

MOP257	High Power RF Distribution and Control for Multi-Cavity Cryomodule Testing	cryomodule, controls, cavity, linac	591
	Y.W. Kang, M. Broyles, M.T. Crofford, X. Geng, S.-H. Kim, S.W. Lee, C.L. Phibbs, K.R. Shin, W.H. Strong ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The SNS has been successfully operating 81 superconducting six-cell cavities in 23 cryomodules in its linac to achieve the goals in beam power and energy. For near-term production of spare cryomodules and the upcoming power upgrade project that will need 36 additional cavities in 9 cryomodules, high RF power testing and qualification of the cavities is required in the RF test facility. Simultaneously powering all the cavities in a cryomodule is considered desirable for robust conditioning and studying of cavity field emission since certain cavities exhibit field emissions that could be mutually coupled. A four-way variable output power waveguide splitting system is being prepared for testing cryomodules with up to four cavities. The splitting system is fed by an 805 MHz, 5 MW peak power pulsed klystron. The power output at each arm can be adjusted in both amplitude and phase to wide ranges of values using two mechanical waveguide phase shifters that form a vector modulator. The system control is implemented in the EPICS environment similar to the main accelerator controls. The work performed on the design, integration, operation, and test of the system are presented.

MOP300	The Spallation Neutron Source Eight-Channel Pulsed Power Meter	EPICS, controls, monitoring, LLRF	684
	M.T. Crofford, X. Geng, T.W. Hardek ORNL, Oak Ridge, Tennessee, USA T.L. Davidson ORNL RAD, Oak Ridge, Tennessee, USA
	The Spallation Neutron Source (SNS) Low Level Radio Frequency (LLRF) Control System currently utilizes the High-Power Protection Module (HPM) to monitor RF power levels, arc faults, and associated signals for the protection of the RF systems and accelerating cavities. The HPM is limited to seven RF channels for monitoring signals which in some instances leaves some signals of interest unmonitored. In addition, the HPM does not support monitoring of RF frequencies below 100 MHz which makes it unusable for our Ring and Ion Source systems that operate at 1 and 2 MHz respectively. To alleviate this problem, we have developed a microprocessor based eight channel pulsed RF power meter that allows us to monitor additional channels between the frequency range of 1 MHz to 2.5 GHz. This meter has been field tested in several locations with good results and plans are in place for a wider deployment.

TUP010	Code TESLA for Modeling and Design of High-Power, High-Efficiency Klystrons	simulation, cavity, electron, gun	826
	I.A. Chernyavskiy SAIC, McLean, USA T.M. Antonsen UMD, College Park, Maryland, USA S.J. Cooke, B. Levush, A.N. Vlasov NRL, Washington, DC, USA
	Funding: This work was supported by the U.S. Office of Naval Research (ONR). This work gives an overview of the main features of the 2.5D large-signal code TESLA and its capabilities for the modelling single-beam and multiple-beam klystrons as high-power RF sources. These sources are widely used or proposed to be used in accelerators in the future. Comparison of TESLA modelling results with experimental data for a few multiple-beam klystrons are shown.

TUP015	Conceptual Design of the Project-X 1.3 GHz, 3-8 GeV Pulsed Linac	linac, cavity, controls, feedback	841
	N. Solyak, Y.I. Eidelman, S. Nagaitsev, J.-F. Ostiguy, A. Vostrikov, V.P. Yakovlev Fermilab, Batavia, USA
	The Project-X, a multi-MW proton source, is under development at Fermilab. It enables a Long Baseline Neutrino Experiment via a new beam line pointed to DUSEL in Lead, South Dakota, and a broad suite of rare decay experiments. The facility contains 3-GeV 1-mA CW superconducting linac. In the second stage of about 5% of the H⁻ beam is accelerated up to 8 GeV in a 1.3 GHz SRF pulse linac to Recycler/Main Injector. In order to mitigate the problem with the stripping foil heating during injection to the Main Injector, the pulses with higher current are accelerated in CW linac together with 1 mA beam for further acceleration in the pulse linac. The optimal current in the pulse linac is discussed as well as limitations that determine it's selection. A concept design of the pulse linac is described. The lattice design is presented as well as RF stability analysis. The necessity of the HOM couplers is discussed also.

TUP061	FPC Conditioning Cart at BNL	vacuum, gun, controls, cavity	928
	W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, A. Burrill, S. Deonarine, D.M. Gassner, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, L. Masi, G.T. McIntyre, D. Pate, D. Phillips, T. Seda, A.N. Steszyn, T.N. Tallerico, R.J. Todd, D. Weiss, A. Zaltsman BNL, Upton, Long Island, New York, USA M.D. Cole, G.J. Whitbeck AES, Medford, NY, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 703MHz superconducting gun will have 2 fundamental power couplers (FPCs). Each FPC will deliver up to 500kW of RF power. In order to prepare the couplers for high power RF service and process multipacting, the FPCs should be conditioned before they are installed in the gun. A conditioning cart based test stand, which includes a vacuum pumping system, controllable bake-out system, diagnostics, interlocks and data log system has been designed, constructed and commissioned by collaboration of BNL and AES. This paper presents FPC conditioning cart systems and summarizes the conditioning process and results.

TUP076	First High Power Pulsed Tests of a Dressed 325 MHz Superconducting Single Spoke Resonator at Fermilab	cavity, linac, vacuum, resonance	964
	R.L. Madrak, J. Branlard, B. Chase, C. Darve, P.W. Joireman, T.N. Khabiboulline, A. Mukherjee, T.H. Nicol, E. Peoples-Evans, D.W. Peterson, Y.M. Pischalnikov, L. Ristori, W. Schappert, D.A. Sergatskov, W.M. Soyars, J. Steimel, I. Terechkine, V. Tupikov, R.L. Wagner, R.C. Webber, D. Wildman Fermilab, Batavia, USA
	In the recently commissioned superconducting RF cavity test facility at Fermilab (SCTF), a 325 MHz, β=0.22 superconducting single-spoke resonator (SSR1) has been tested for the first time with its input power coupler. Previously, this cavity had been tested CW with a low power, high Qext test coupler; first as a bare cavity in the Fermilab Vertical Test Stand and then fully dressed in the SCTF. For the tests described here, the design input coupler with Q_ext ~ 10⁶ was used. Pulsed power was provided by a Toshiba E3740A 2.5 MW klystron.

TUP123	Performance of the 352-MHz 4-kW CW Solid State RF Power Amplifier System using 1-kW Push-pull Devices	controls, cavity, storage-ring, simulation	1059
	D. Horan, G.J. Waldschmidt ANL, Argonne, USA
	Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 Development and testing of a prototype 352-MHz, 4-kW cw solid state rf power amplifier system is underway at the Advanced Photon Source to study and evaluate the performance advantages of an upgrade to solid state rf power technology at the APS. General performance measurement data on the assembled amplifier system is discussed, with emphasis on efficiency improvements possible through the use of dynamic drain voltage control.

TUP125	High Power RF Systems for the BNL ERL Project	cavity, power-supply, electron, gun	1065
	A. Zaltsman, R.F. Lambiase BNL, Upton, Long Island, New York, USA
	The Energy Recovery Linac (ERL) project, now under construction at Brookhaven National Laboratory, requires two high power RF systems. The first RF system is for the 703.75 MHz superconducting electron gun. The RF power from this system is used to drive nearly half an Ampere of beam current to 2.5 MeV. There is no provision to recover any of this energy so the minimum amplifier power is 1 MW. It consists of 1 MW CW klystron, transmitter and power supplies, 1 MW circulator, 1 MW dummy load and a two-way power splitter. The second RF system is for the 703.75 MHz superconducting cavity. The system accelerates the beam to 54.7 MeV and recovers this energy. It will provide up to 50 kW of CW RF power to the cavity. It consists of 50 kW transmitter, circulator, and dummy load. This paper describes the two high power RF systems and presents the test data for both.

TUP126	Development of a 10 kW CW, S-Band, PPM Focused Klystron	electron, cavity, simulation, gun	1068
	P. Ferguson, R.L. Ives, D. Marsden, M.E. Read CCR, San Mateo, California, USA
	Funding: US Department of Energy SBIR Contract DE-SC0004558 Calabazas Creek Research Inc. (CCR) is developing a 100 kW CW, 2.815 GHz klystron for use in the Advanced Photon Source upgrade light source at Argonne National Laboratory. Periodic permanent magnet (PPM) focusing is used to avoid loss in efficiency due to the power normally required for a solenoid. The PPM structure elements consist of 4 disk (pill box) magnets with a clover-leaf shaped iron pole piece. The gaps between the magnets permit the introduction of liquid cooling into the RF circuit. Design tools include the large signal codes KLSC and TESLA for the efficiency calculations, MAXWELL 3D for the magnetic fields, and the CCR 3D code BOA for the beam trajectories. From initial simulations with seven cavities, the efficiency will be over 62% with a beam voltage of 47 kV. The saturated gain is 44 dB. The design emphasizes high reliability, with simple construction, robust cooling and low thermal loading through high efficiency. The paper will include the details of the design, including results of the simulations of the RF and magnetic structures, beam trajectories, and thermo-mechanical analyses.

TUP128	Development of a 402.5 MHz 140 kW Inductive Output Tube (IOT)	gun, electron, cavity, simulation	1070
	M.E. Read, T. Bui, R.L. Ives, R.H. Jackson CCR, San Mateo, California, USA I.A. Chernyavskiy, H. Freund SAIC, McLean, USA
	Funding: US Department of Energy under SBIR contract DE-SC0004566 Calabazas Creek Research Inc. (CCR) is developing a pulsed 140 kW, 402.5 MHz Inductive Output Tube (IOT) for use in proton accelerators. Unlike other high power multiple-beam IOT's currently under development, this device will use a single electron beam, and will be less expensive and have a higher reliability. The program includes the use of new design tools, including NEMESIS and a version of CCR's 3D Beam Optics Analysis (BOA) code modified to include time dependent modeling. The design will include the electron gun, collector, input and output cavities, input and output couplers and the RF output window. An emphasis will be placed on the electron gun, which will as usual include a grid for the high frequency modulation, and the input cavity. The new version of BOA is expected to be particularly useful in modeling the formation of the bunched beam and will replace the relatively slow 3D PIC code MAGIC as the primary design tool. HFSS and NEMESIS will be used for design of the input cavity. The paper will include details of the design.

TUP132	50 MW X-Band RF System for a Photoinjector Test Station at LLNL	electron, linac, high-voltage, emittance	1082
	T.L. Houck, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, R.A. Marsh LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office. In support of x-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. The timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW of RF power will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.

TUP141	RF Solid State Driver for Argonne Light Source	booster, storage-ring, background, simulation	1097
	B. Popovic University of Iowa, Iowa City, Iowa, USA G.J. Waldschmidt ANL, Argonne, USA
	Funding: 2010 Lee Teng Summer Student Program at Argonne National Laboratory Currently, power to the APS storage ring and Booster cavities is provided from klystrons with a eventual goal to move to a solid state RF system. A modular design centered around a 1 kW amplifier has been decided on. The driver amplifier was created for this module system using Agilent’s ADS circuit simulation software and then built and tested.

TUP255	Solid-State Transmitter for a 2 MW Klystron	controls, cathode, high-voltage, monitoring	1304
	M.K. Kempkes, M.P.J. Gaudreau, T.H. Hawkey, K. Schrock Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Diversified Technologies, Inc. delivered a transmitter for a 2 MW, 500 MHz klystron manufactured by Communications and Power Industries, Inc. The transmitter design eliminates the need for a large pulse transformer; eliminates the crowbar for greater system availability and klystron reliability, and provides full control and monitoring of critical transmitter functions, settings, and fault diagnostics. The klystron beam power is generated by two high voltage power supplies, each capable of producing 150 kW CW power at 100 kV, with ~0.1% regulation. The transmitter can operate at lower average power in the unlikely event a single power supply goes off-line. The main solid-state switch, a series stack of commercially available IGBTs, delivers a range of HV pulsewidths to the klystron under normal operating conditions, and protects the klystron against arc damage. Should the current in the switch exceed a preset fault threshold value, the switch opens in ~ 1 μs to disconnect the high voltage from the klystron. In this paper, DTI will describe the architecture of the 2 MW klystron transmitter and its present status.

TUP261	The ILC P2 Marx and Application of the Marx Topology to Future Accelerators	controls, power-supply, FEL, high-voltage	1313
	M.A. Kemp, A.L. Benwell, C. Burkhart, J. Hugyik, R.S. Larsen, D.J. MacNair, K.J.P. Macken, M.N. Nguyen, J.J. Olsen SLAC, Menlo Park, California, USA
	Funding: Work supported by the US Department of Energy under contract DE-AC02-76SF00515. The SLAC P2 Marx is under development for the ILC linac klystron modulator. Specifications are for an output of 120 kV, 140 A, 1.6 ms pulse width, 5 Hz pulse repetition frequency, and ± 0.5% flat-top. The SLAC P2 Marx builds upon the success of the P1 Marx, which is currently undergoing lifetime evaluation. While the P2 Marx’s target application is the ILC, characteristics of the Marx topology make it equally well-suited for different parameter ranges; for example, increased pulse repetition frequency, increased output current, longer pulse width, etc. Marx parameters such as the number of cells, cell capacitance, and component selection can be optimized for the application. This paper provides an overview of the P2 Marx development including design, fabrication progress, and test results for the modulator and sub-assemblies. High-availability features of the modulator such as the diagnostic/prognostic embedded control system and fault-adaptive automatic reconfiguration will be detailed. In addition, the scalability of the Marx topology to other long-pulse parameter ranges will be highlighted. Topology adaptations for several proposed accelerators will be presented.

TUP275	SNS Linac Modulator Operational History and Performance	linac, neutron, high-voltage, monitoring	1340
	V.V. Peplov, D.E. Anderson, R.I. Cutler, M. Wezensky ORNL, Oak Ridge, Tennessee, USA J.D. Hicks, R.B. Saethre ORNL RAD, Oak Ridge, Tennessee, USA
	Fourteen High Voltage Converter Modulators (HVCM) were initially installed at the Spallation Neutron Source Linear Accelerator (SNS Linac) at the Oak Ridge National Laboratory in 2005. A fifteenth HVCM was added in 2009. Each modulator provides a pulse of up to 140 kV at a maximum width of 1.35 msec. Peak power level is 11 MW with an 8% duty factor. The HVCM system must be available for neutron production (NP) 24/7 with the exception being two, 6-week maintenance periods per year. HVCM reliability is one of the most important factors to maximize Linac availability and achieve SNS performance goals. During the last few years several modifications have been implemented to improve the overall system reliability. This paper presents operational history of the HVCM systems and examines failure mode statistical data since the modulators began operating at 60 Hz. System enhancements and upgrades aimed at providing long term reliable operation with minimal down time are also discussed in the paper.

WEODS1	Design and Optimization of Future X-ray FELs based on Advanced High Frequency Linacs	linac, impedance, FEL, acceleration	1491
	F. Wang SLAC, Menlo Park, California, USA
	To drive future XFELs, normal-conducting linacs at various rf freqencies are being considered. With optimized accelerator structures and rf systems, a higher rf frequency linac has several advantages, such as high acceleration gradient and high rf-to-beam efficiency. This paper presents a comparison of possible S-band, C-band and X-band linac designs for two cases, single bunch operation and multibunch operation, where the bunch train length is longer than the structure fill time and the beam loading is small. General scaling laws for the main linac parameters, which can be useful in the design such linacs, are derived.
	Slides WEODS1 [5.795 MB]

THOAS2	Solid State RF Power - The route to 1W per Euro Cent	electron, radiation, linac, synchrotron	2047
	O. Heid Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany T.J.S. Hughes Siemens AG, Erlangen, Germany
	In most particle accelerators RF power is a decisive design constraint due to high costs and relative inflexibility of power sources based on electron beams i.e. Klystrons, Magnetrons, Tetrodes etc. At VHF/UHF frequencies the transition to solid state devices promises to fundamentally change the situation. Recent progress brings 1 Watt per Euro cent installed cost within reach. We present a Silicon Carbide semiconductor solution utilising the Solid State Direct Drive technology [,,*] at unprecedented efficiency, power levels and power densities. The proposed solutions allows retrofitting of existing RF solutions and opens the route to novel accelerator designs. Heid O., Hughes T. THPD002, IPAC10, Kyoto, Japan Hergt M et al, 2010 IEEE International Power Modulator and High Voltage Conf., Atlanta GA, USA * Heid O., Hughes T. THP068, LINAC10, Tsukuba, Japan
	Slides THOAS2 [1.776 MB]

THOAS3	Status of the Oak Ridge Spallation Neutron Source (SNS) RF Systems	controls, linac, rfq, neutron	2050
	T.W. Hardek, M.T. Crofford, Y.W. Kang, M.F. Piller, A.V. Vassioutchenko ORNL, Oak Ridge, Tennessee, USA S.W. Lee, M.E. Middendorf ORNL RAD, Oak Ridge, Tennessee, USA
	The SNS has been delivering production neutrons for five years with first beam delivered to the neutron target at the end of April 2006. On September 18, 2009 SNS officially reached 1 megawatt of beam on target marking the achievement of a decades-old dream of providing a U.S. megawatt class pulsed spallation source. The SNS is now routinely delivering 1 megawatt of beam power to the neutron target at over 85 percent of the scheduled beam time. The present effort is aimed at increasing availability eventually to 95 percent and gradually increasing the intensity to the 1.4 megawatt design level. While the RF systems have performed well since initial installation some improvements have been implemented. This paper provides a review of the SNS RF Systems, an overview of the performance of the various components and a detailed review of RF related issues addressed over the past several years.
	Slides THOAS3 [2.759 MB]

THOBN5	Design and Testing of Advanced Photonic Bandgap (PBG) Accelerator Structures	diagnostics, wakefield, coupling, ion	2071
	B.J. Munroe, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA V.A. Dolgashev, S.G. Tantawi, A.D. Yeremian SLAC, Menlo Park, California, USA R.A. Marsh LLNL, Livermore, California, USA
	Photonic Band-gap (PBG) structures continue to be an area of promising research for high gradient accelerators with wakefield suppression. Experimental results on an 11.4 GHz PBG structure tested at high power and high repetition rate at SLAC have shown that high gradients can be achieved in these structures. For PBG structures with thin rods, however, pulsed heating of the inner row of rods is a problem. Following these preliminary results, two new PBG structures have been designed. One structure, designated 1C-SW-A5.65-T4.6-Cu-PBG2-SLAC1, utilizes elliptical inner rods to reduce pulsed heating to an acceptable level; it will be tested at SLAC. A second PBG structure with round rods will be tested at 17.1 GHz at MIT. The MIT research will use the improved diagnostic access of the PBG structure to obtain a better understanding of the breakdown process. We will present preliminary results for the design and testing of these PBG structures.
	Slides THOBN5 [0.752 MB]

THOCN4	High-Power Options for LANSCE	DTL, linac, neutron, proton	2107
	R.W. Garnett, E.J. Pitcher, D. Rees, L. Rybarcyk, T. Tajima LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the U. S. Department of Energy Contract DE-AC52-06NA25396. The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including schemes for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several plausible options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.
	Slides THOCN4 [2.903 MB]

THOCS4	RF Power Upgrade for CEBAF at Jefferson Laboratory	solenoid, controls, cavity, cryomodule	2127
	A.J. Kimber, R.M. Nelson JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Jefferson Laboratory (JLab) is currently upgrading the 6GeV Continuous Electron Beam Accelerator Facility (CEBAF) to 12GeV. As part of the upgrade, RF systems will be added, bringing the total from 340 to 420. Existing RF systems can provide up to 6.5 kW of CW RF at 1497 MHZ. The 80 new systems will provide increased RF power of up to 13 kW CW each. Built around a newly designed and higher efficiency 13 kW klystron developed for JLab by L-3 Communications, each new RF chain is a completely revamped system using hardware different than our present installations. This paper will discuss the main components of the new systems including the 13 kW klystron, waveguide isolator, and HV power supply using switch-mode technology. Methodology for selection of the various components and results of initial testing will also be addressed.
	Slides THOCS4 [3.364 MB]

THP078	Study of a TeV Level Linear Collider Using Short rf Pulse (~20ns) Two Beam Accelerator Concept	collider, linear-collider, linac, wakefield	2279
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, J.G. Power ANL, Argonne, USA
	Funding: Work is supported by DOE SBIR grant under contract No. DE-SC0004320. In a general sense, a high gradient is desirable for a TeV level linear collider design because it can reduce the total linac length. More importantly, the efficiency and the cost to sustain such a gradient should be considered as well in the optimization process of an overall design. We propose a high energy linear collider based on a short rf pulse (~22ns flat top), high gradient (~267MV/m loaded gradient), high frequency (26GHz) dielectric two beam accelerator scheme. This scheme is a modular design and its unique locally repetitive drive beam structure allows a flexible configuration to meet different needs. Major parameters of a conceptual 3-TeV linear collider are presented. This preliminary study shows an efficient (~7% overall ) short pulse collider may be achievable. As the first step, a dielectric based broadband accelerating structure is under development.

THP124	Higher Current Operation for the APS Upgrade	HOM, cavity, lattice, feedback	2351
	K.C. Harkay, G. Berenc, M. Borland, Y.-C. Chae, L. Emery, D. Horan, R. Nassiri, V. Sajaev, K.M. Schroeder, G.J. Waldschmidt, A. Xiao, C. Yao ANL, Argonne, USA
	Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source is a 7-GeV hard x-ray synchrotron light source. Operation for users is delivered at a nominal current of 100 mA in one of three bunch patterns. The APS Upgrade calls for a minimum planned operating current of 150 mA, with an option to deliver beam up to 200 mA. The high-current threshold in the storage ring has been explored, and storage ring components have been identified that either drive collective instabilities or are subjected to excessive beam-drive higher-order-mode (HOM) heating. In this paper, we describe machine studies at 150 mA in a special lattice that simulates the upgraded APS. We also describe the accelerator upgrades that are required to accommodate 200-mA operation, as well as the ongoing machine studies plan.

FROBS4	NSLS-II RF Systems	cavity, storage-ring, linac, coupling	2583
	J. Rose, W.K. Gash, B. Holub, Y. Kawashima, H. Ma, N.A. Towne, M. Yeddulla BNL, Upton, Long Island, New York, USA
	The NSLS-II RF systems include solid state modulators for the S-band klystrons powering the traveling wave sections for the 200 MeV injector linac, 7 cell cavity with IOT amplifier for the 3 GeV booster synchrotron and superconducting 500 MHz cavities powered by klystrons and a passive 1500 MHz SRF cavity for the 3 GeV, 500 mA storage ring. The systems are controlled by digital I/Q modulators fed by an ultra-low noise master oscillator. System overviews will be given along with preliminary test data.
	Slides FROBS4 [1.041 MB]

Paper

Title

Other Keywords

Page

MOP012

Ultra-High Gradient Compact S-Band Accelerating Structure

coupling, linac, vacuum, simulation

127

L. Faillace, R.B. Agustsson, P. Frigola, A.Y. Murokh
RadiaBeam, Santa Monica, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

Funding: Dept. of Energy DE-SC0000866
In this paper, we present the radio-frequency design of the DECA (Doubled Energy Compact Accelerator) S-band accelerating structure operating in the pi-mode at 2.856 GHz, where RF power sources are commonly available. The development of the DECA structure will offer an ultra-compact drop-in replacement for a conventional S-band linac in research and industrial applications such as drivers for compact light sources, medical and security systems. The electromagnetic design has been performed with the codes SuperFish and HFSS. The choice of the single cell shape derives from an optimization process aiming to maximize RF efficiency and minimize surface fields at very high accelerating gradients, i.e. 50 MV/m and above. Such gradients can be achieved utilizing shape-optimized elliptical irises, dual-feed couplers with the "fat-lip" coupling slot geometry, and specialized fabrication procedures developed for high gradient structures. The thermal-stress analysis of the DECA structure is also presented.
* V. Dolgashev, "Status of X-band Standing Wave Structure Studies at SLAC", SLAC-PUB-10124, (2003).
** C. Limborg et al., "RF Design of LCLS Gun", LCLS-TN-05-03 (2005).

MOP144

Multi-Harmonic Cavity for RF Breakdown Studies

cavity, acceleration, cathode, electron

361

Y. Jiang
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
S. Kazakov, S.V. Kuzikov
Omega-P, Inc., New Haven, Connecticut, USA

Funding: DOE, Office of HEP
An axially-asymmetric cavity to support several modes at harmonically-related frequencies is predicted to sustain higher RF breakdown thresholds than a conventional pillbox cavity, when driven by two or more external RF phase-locked harmonic sources. Experimental efforts are underway at Yale Beam Physics Lab to study RF breakdown in a bimodal asymmetric cavity. Such a cavity could be a basic building-block for a future high-gradient warm accelerator structure.
* S.Yu. Kazakov, S.V. Kuzikov, Y. Jiang, and J.L. Hirshfield, PRSTAB, 13, 071303 (2010).
** S.V. Kuzikov, S.Yu. Kazakov, Y. Jiang, and J.L. Hirshfield, PRL 104, 214801 (2010).

MOP257

High Power RF Distribution and Control for Multi-Cavity Cryomodule Testing

cryomodule, controls, cavity, linac

591

Y.W. Kang, M. Broyles, M.T. Crofford, X. Geng, S.-H. Kim, S.W. Lee, C.L. Phibbs, K.R. Shin, W.H. Strong
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The SNS has been successfully operating 81 superconducting six-cell cavities in 23 cryomodules in its linac to achieve the goals in beam power and energy. For near-term production of spare cryomodules and the upcoming power upgrade project that will need 36 additional cavities in 9 cryomodules, high RF power testing and qualification of the cavities is required in the RF test facility. Simultaneously powering all the cavities in a cryomodule is considered desirable for robust conditioning and studying of cavity field emission since certain cavities exhibit field emissions that could be mutually coupled. A four-way variable output power waveguide splitting system is being prepared for testing cryomodules with up to four cavities. The splitting system is fed by an 805 MHz, 5 MW peak power pulsed klystron. The power output at each arm can be adjusted in both amplitude and phase to wide ranges of values using two mechanical waveguide phase shifters that form a vector modulator. The system control is implemented in the EPICS environment similar to the main accelerator controls. The work performed on the design, integration, operation, and test of the system are presented.

MOP300

The Spallation Neutron Source Eight-Channel Pulsed Power Meter

EPICS, controls, monitoring, LLRF

684

M.T. Crofford, X. Geng, T.W. Hardek
ORNL, Oak Ridge, Tennessee, USA
T.L. Davidson
ORNL RAD, Oak Ridge, Tennessee, USA

The Spallation Neutron Source (SNS) Low Level Radio Frequency (LLRF) Control System currently utilizes the High-Power Protection Module (HPM) to monitor RF power levels, arc faults, and associated signals for the protection of the RF systems and accelerating cavities. The HPM is limited to seven RF channels for monitoring signals which in some instances leaves some signals of interest unmonitored. In addition, the HPM does not support monitoring of RF frequencies below 100 MHz which makes it unusable for our Ring and Ion Source systems that operate at 1 and 2 MHz respectively. To alleviate this problem, we have developed a microprocessor based eight channel pulsed RF power meter that allows us to monitor additional channels between the frequency range of 1 MHz to 2.5 GHz. This meter has been field tested in several locations with good results and plans are in place for a wider deployment.

TUP010

Code TESLA for Modeling and Design of High-Power, High-Efficiency Klystrons

simulation, cavity, electron, gun

826

I.A. Chernyavskiy
SAIC, McLean, USA
T.M. Antonsen
UMD, College Park, Maryland, USA
S.J. Cooke, B. Levush, A.N. Vlasov
NRL, Washington, DC, USA

Funding: This work was supported by the U.S. Office of Naval Research (ONR).
This work gives an overview of the main features of the 2.5D large-signal code TESLA and its capabilities for the modelling single-beam and multiple-beam klystrons as high-power RF sources. These sources are widely used or proposed to be used in accelerators in the future. Comparison of TESLA modelling results with experimental data for a few multiple-beam klystrons are shown.

TUP015

Conceptual Design of the Project-X 1.3 GHz, 3-8 GeV Pulsed Linac

linac, cavity, controls, feedback

841

N. Solyak, Y.I. Eidelman, S. Nagaitsev, J.-F. Ostiguy, A. Vostrikov, V.P. Yakovlev
Fermilab, Batavia, USA

The Project-X, a multi-MW proton source, is under development at Fermilab. It enables a Long Baseline Neutrino Experiment via a new beam line pointed to DUSEL in Lead, South Dakota, and a broad suite of rare decay experiments. The facility contains 3-GeV 1-mA CW superconducting linac. In the second stage of about 5% of the H⁻ beam is accelerated up to 8 GeV in a 1.3 GHz SRF pulse linac to Recycler/Main Injector. In order to mitigate the problem with the stripping foil heating during injection to the Main Injector, the pulses with higher current are accelerated in CW linac together with 1 mA beam for further acceleration in the pulse linac. The optimal current in the pulse linac is discussed as well as limitations that determine it's selection. A concept design of the pulse linac is described. The lattice design is presented as well as RF stability analysis. The necessity of the HOM couplers is discussed also.

TUP061

FPC Conditioning Cart at BNL

vacuum, gun, controls, cavity

928

W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, A. Burrill, S. Deonarine, D.M. Gassner, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, L. Masi, G.T. McIntyre, D. Pate, D. Phillips, T. Seda, A.N. Steszyn, T.N. Tallerico, R.J. Todd, D. Weiss, A. Zaltsman
BNL, Upton, Long Island, New York, USA
M.D. Cole, G.J. Whitbeck
AES, Medford, NY, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 703MHz superconducting gun will have 2 fundamental power couplers (FPCs). Each FPC will deliver up to 500kW of RF power. In order to prepare the couplers for high power RF service and process multipacting, the FPCs should be conditioned before they are installed in the gun. A conditioning cart based test stand, which includes a vacuum pumping system, controllable bake-out system, diagnostics, interlocks and data log system has been designed, constructed and commissioned by collaboration of BNL and AES. This paper presents FPC conditioning cart systems and summarizes the conditioning process and results.

TUP076

First High Power Pulsed Tests of a Dressed 325 MHz Superconducting Single Spoke Resonator at Fermilab

cavity, linac, vacuum, resonance

964

R.L. Madrak, J. Branlard, B. Chase, C. Darve, P.W. Joireman, T.N. Khabiboulline, A. Mukherjee, T.H. Nicol, E. Peoples-Evans, D.W. Peterson, Y.M. Pischalnikov, L. Ristori, W. Schappert, D.A. Sergatskov, W.M. Soyars, J. Steimel, I. Terechkine, V. Tupikov, R.L. Wagner, R.C. Webber, D. Wildman
Fermilab, Batavia, USA

In the recently commissioned superconducting RF cavity test facility at Fermilab (SCTF), a 325 MHz, β=0.22 superconducting single-spoke resonator (SSR1) has been tested for the first time with its input power coupler. Previously, this cavity had been tested CW with a low power, high Qext test coupler; first as a bare cavity in the Fermilab Vertical Test Stand and then fully dressed in the SCTF. For the tests described here, the design input coupler with Q_ext ~ 10⁶ was used. Pulsed power was provided by a Toshiba E3740A 2.5 MW klystron.

TUP123

Performance of the 352-MHz 4-kW CW Solid State RF Power Amplifier System using 1-kW Push-pull Devices

controls, cavity, storage-ring, simulation

1059

D. Horan, G.J. Waldschmidt
ANL, Argonne, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Development and testing of a prototype 352-MHz, 4-kW cw solid state rf power amplifier system is underway at the Advanced Photon Source to study and evaluate the performance advantages of an upgrade to solid state rf power technology at the APS. General performance measurement data on the assembled amplifier system is discussed, with emphasis on efficiency improvements possible through the use of dynamic drain voltage control.

TUP125

High Power RF Systems for the BNL ERL Project

cavity, power-supply, electron, gun

1065

A. Zaltsman, R.F. Lambiase
BNL, Upton, Long Island, New York, USA

The Energy Recovery Linac (ERL) project, now under construction at Brookhaven National Laboratory, requires two high power RF systems. The first RF system is for the 703.75 MHz superconducting electron gun. The RF power from this system is used to drive nearly half an Ampere of beam current to 2.5 MeV. There is no provision to recover any of this energy so the minimum amplifier power is 1 MW. It consists of 1 MW CW klystron, transmitter and power supplies, 1 MW circulator, 1 MW dummy load and a two-way power splitter. The second RF system is for the 703.75 MHz superconducting cavity. The system accelerates the beam to 54.7 MeV and recovers this energy. It will provide up to 50 kW of CW RF power to the cavity. It consists of 50 kW transmitter, circulator, and dummy load. This paper describes the two high power RF systems and presents the test data for both.

TUP126

Development of a 10 kW CW, S-Band, PPM Focused Klystron

electron, cavity, simulation, gun

1068

P. Ferguson, R.L. Ives, D. Marsden, M.E. Read
CCR, San Mateo, California, USA

Funding: US Department of Energy SBIR Contract DE-SC0004558
Calabazas Creek Research Inc. (CCR) is developing a 100 kW CW, 2.815 GHz klystron for use in the Advanced Photon Source upgrade light source at Argonne National Laboratory. Periodic permanent magnet (PPM) focusing is used to avoid loss in efficiency due to the power normally required for a solenoid. The PPM structure elements consist of 4 disk (pill box) magnets with a clover-leaf shaped iron pole piece. The gaps between the magnets permit the introduction of liquid cooling into the RF circuit. Design tools include the large signal codes KLSC and TESLA for the efficiency calculations, MAXWELL 3D for the magnetic fields, and the CCR 3D code BOA for the beam trajectories. From initial simulations with seven cavities, the efficiency will be over 62% with a beam voltage of 47 kV. The saturated gain is 44 dB. The design emphasizes high reliability, with simple construction, robust cooling and low thermal loading through high efficiency. The paper will include the details of the design, including results of the simulations of the RF and magnetic structures, beam trajectories, and thermo-mechanical analyses.

TUP128

Development of a 402.5 MHz 140 kW Inductive Output Tube (IOT)

gun, electron, cavity, simulation

1070

M.E. Read, T. Bui, R.L. Ives, R.H. Jackson
CCR, San Mateo, California, USA
I.A. Chernyavskiy, H. Freund
SAIC, McLean, USA

Funding: US Department of Energy under SBIR contract DE-SC0004566
Calabazas Creek Research Inc. (CCR) is developing a pulsed 140 kW, 402.5 MHz Inductive Output Tube (IOT) for use in proton accelerators. Unlike other high power multiple-beam IOT's currently under development, this device will use a single electron beam, and will be less expensive and have a higher reliability. The program includes the use of new design tools, including NEMESIS and a version of CCR's 3D Beam Optics Analysis (BOA) code modified to include time dependent modeling. The design will include the electron gun, collector, input and output cavities, input and output couplers and the RF output window. An emphasis will be placed on the electron gun, which will as usual include a grid for the high frequency modulation, and the input cavity. The new version of BOA is expected to be particularly useful in modeling the formation of the bunched beam and will replace the relatively slow 3D PIC code MAGIC as the primary design tool. HFSS and NEMESIS will be used for design of the input cavity. The paper will include details of the design.

TUP132

50 MW X-Band RF System for a Photoinjector Test Station at LLNL

electron, linac, high-voltage, emittance

1082

T.L. Houck, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, R.A. Marsh
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office.
In support of x-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. The timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW of RF power will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.

TUP141

RF Solid State Driver for Argonne Light Source

booster, storage-ring, background, simulation

1097

B. Popovic
University of Iowa, Iowa City, Iowa, USA
G.J. Waldschmidt
ANL, Argonne, USA

Funding: 2010 Lee Teng Summer Student Program at Argonne National Laboratory
Currently, power to the APS storage ring and Booster cavities is provided from klystrons with a eventual goal to move to a solid state RF system. A modular design centered around a 1 kW amplifier has been decided on. The driver amplifier was created for this module system using Agilent’s ADS circuit simulation software and then built and tested.

TUP255

Solid-State Transmitter for a 2 MW Klystron

controls, cathode, high-voltage, monitoring

1304

M.K. Kempkes, M.P.J. Gaudreau, T.H. Hawkey, K. Schrock
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Diversified Technologies, Inc. delivered a transmitter for a 2 MW, 500 MHz klystron manufactured by Communications and Power Industries, Inc. The transmitter design eliminates the need for a large pulse transformer; eliminates the crowbar for greater system availability and klystron reliability, and provides full control and monitoring of critical transmitter functions, settings, and fault diagnostics. The klystron beam power is generated by two high voltage power supplies, each capable of producing 150 kW CW power at 100 kV, with ~0.1% regulation. The transmitter can operate at lower average power in the unlikely event a single power supply goes off-line. The main solid-state switch, a series stack of commercially available IGBTs, delivers a range of HV pulsewidths to the klystron under normal operating conditions, and protects the klystron against arc damage. Should the current in the switch exceed a preset fault threshold value, the switch opens in ~ 1 μs to disconnect the high voltage from the klystron. In this paper, DTI will describe the architecture of the 2 MW klystron transmitter and its present status.

TUP261

The ILC P2 Marx and Application of the Marx Topology to Future Accelerators

controls, power-supply, FEL, high-voltage

1313

M.A. Kemp, A.L. Benwell, C. Burkhart, J. Hugyik, R.S. Larsen, D.J. MacNair, K.J.P. Macken, M.N. Nguyen, J.J. Olsen
SLAC, Menlo Park, California, USA

Funding: Work supported by the US Department of Energy under contract DE-AC02-76SF00515.
The SLAC P2 Marx is under development for the ILC linac klystron modulator. Specifications are for an output of 120 kV, 140 A, 1.6 ms pulse width, 5 Hz pulse repetition frequency, and ± 0.5% flat-top. The SLAC P2 Marx builds upon the success of the P1 Marx, which is currently undergoing lifetime evaluation. While the P2 Marx’s target application is the ILC, characteristics of the Marx topology make it equally well-suited for different parameter ranges; for example, increased pulse repetition frequency, increased output current, longer pulse width, etc. Marx parameters such as the number of cells, cell capacitance, and component selection can be optimized for the application. This paper provides an overview of the P2 Marx development including design, fabrication progress, and test results for the modulator and sub-assemblies. High-availability features of the modulator such as the diagnostic/prognostic embedded control system and fault-adaptive automatic reconfiguration will be detailed. In addition, the scalability of the Marx topology to other long-pulse parameter ranges will be highlighted. Topology adaptations for several proposed accelerators will be presented.

TUP275

SNS Linac Modulator Operational History and Performance

linac, neutron, high-voltage, monitoring

1340

V.V. Peplov, D.E. Anderson, R.I. Cutler, M. Wezensky
ORNL, Oak Ridge, Tennessee, USA
J.D. Hicks, R.B. Saethre
ORNL RAD, Oak Ridge, Tennessee, USA

Fourteen High Voltage Converter Modulators (HVCM) were initially installed at the Spallation Neutron Source Linear Accelerator (SNS Linac) at the Oak Ridge National Laboratory in 2005. A fifteenth HVCM was added in 2009. Each modulator provides a pulse of up to 140 kV at a maximum width of 1.35 msec. Peak power level is 11 MW with an 8% duty factor. The HVCM system must be available for neutron production (NP) 24/7 with the exception being two, 6-week maintenance periods per year. HVCM reliability is one of the most important factors to maximize Linac availability and achieve SNS performance goals. During the last few years several modifications have been implemented to improve the overall system reliability. This paper presents operational history of the HVCM systems and examines failure mode statistical data since the modulators began operating at 60 Hz. System enhancements and upgrades aimed at providing long term reliable operation with minimal down time are also discussed in the paper.

WEODS1

Design and Optimization of Future X-ray FELs based on Advanced High Frequency Linacs

linac, impedance, FEL, acceleration

1491

F. Wang
SLAC, Menlo Park, California, USA

To drive future XFELs, normal-conducting linacs at various rf freqencies are being considered. With optimized accelerator structures and rf systems, a higher rf frequency linac has several advantages, such as high acceleration gradient and high rf-to-beam efficiency. This paper presents a comparison of possible S-band, C-band and X-band linac designs for two cases, single bunch operation and multibunch operation, where the bunch train length is longer than the structure fill time and the beam loading is small. General scaling laws for the main linac parameters, which can be useful in the design such linacs, are derived.

Slides WEODS1 [5.795 MB]

THOAS2

Solid State RF Power - The route to 1W per Euro Cent

electron, radiation, linac, synchrotron

2047

O. Heid
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
T.J.S. Hughes
Siemens AG, Erlangen, Germany

In most particle accelerators RF power is a decisive design constraint due to high costs and relative inflexibility of power sources based on electron beams i.e. Klystrons, Magnetrons, Tetrodes etc. At VHF/UHF frequencies the transition to solid state devices promises to fundamentally change the situation. Recent progress brings 1 Watt per Euro cent installed cost within reach. We present a Silicon Carbide semiconductor solution utilising the Solid State Direct Drive technology [*,**,***] at unprecedented efficiency, power levels and power densities. The proposed solutions allows retrofitting of existing RF solutions and opens the route to novel accelerator designs.
* Heid O., Hughes T. THPD002, IPAC10, Kyoto, Japan
** Hergt M et al, 2010 IEEE International Power Modulator and High Voltage Conf., Atlanta GA, USA
*** Heid O., Hughes T. THP068, LINAC10, Tsukuba, Japan

Slides THOAS2 [1.776 MB]

THOAS3

Status of the Oak Ridge Spallation Neutron Source (SNS) RF Systems

controls, linac, rfq, neutron

2050

T.W. Hardek, M.T. Crofford, Y.W. Kang, M.F. Piller, A.V. Vassioutchenko
ORNL, Oak Ridge, Tennessee, USA
S.W. Lee, M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

The SNS has been delivering production neutrons for five years with first beam delivered to the neutron target at the end of April 2006. On September 18, 2009 SNS officially reached 1 megawatt of beam on target marking the achievement of a decades-old dream of providing a U.S. megawatt class pulsed spallation source. The SNS is now routinely delivering 1 megawatt of beam power to the neutron target at over 85 percent of the scheduled beam time. The present effort is aimed at increasing availability eventually to 95 percent and gradually increasing the intensity to the 1.4 megawatt design level. While the RF systems have performed well since initial installation some improvements have been implemented. This paper provides a review of the SNS RF Systems, an overview of the performance of the various components and a detailed review of RF related issues addressed over the past several years.

Slides THOAS3 [2.759 MB]

THOBN5

Design and Testing of Advanced Photonic Bandgap (PBG) Accelerator Structures

diagnostics, wakefield, coupling, ion

2071

B.J. Munroe, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA
V.A. Dolgashev, S.G. Tantawi, A.D. Yeremian
SLAC, Menlo Park, California, USA
R.A. Marsh
LLNL, Livermore, California, USA

Photonic Band-gap (PBG) structures continue to be an area of promising research for high gradient accelerators with wakefield suppression. Experimental results on an 11.4 GHz PBG structure tested at high power and high repetition rate at SLAC have shown that high gradients can be achieved in these structures. For PBG structures with thin rods, however, pulsed heating of the inner row of rods is a problem. Following these preliminary results, two new PBG structures have been designed. One structure, designated 1C-SW-A5.65-T4.6-Cu-PBG2-SLAC1, utilizes elliptical inner rods to reduce pulsed heating to an acceptable level; it will be tested at SLAC. A second PBG structure with round rods will be tested at 17.1 GHz at MIT. The MIT research will use the improved diagnostic access of the PBG structure to obtain a better understanding of the breakdown process. We will present preliminary results for the design and testing of these PBG structures.

Slides THOBN5 [0.752 MB]

THOCN4

High-Power Options for LANSCE

DTL, linac, neutron, proton

2107

R.W. Garnett, E.J. Pitcher, D. Rees, L. Rybarcyk, T. Tajima
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the U. S. Department of Energy Contract DE-AC52-06NA25396.
The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including schemes for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several plausible options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.

Slides THOCN4 [2.903 MB]

THOCS4

RF Power Upgrade for CEBAF at Jefferson Laboratory

solenoid, controls, cavity, cryomodule

2127

A.J. Kimber, R.M. Nelson
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Jefferson Laboratory (JLab) is currently upgrading the 6GeV Continuous Electron Beam Accelerator Facility (CEBAF) to 12GeV. As part of the upgrade, RF systems will be added, bringing the total from 340 to 420. Existing RF systems can provide up to 6.5 kW of CW RF at 1497 MHZ. The 80 new systems will provide increased RF power of up to 13 kW CW each. Built around a newly designed and higher efficiency 13 kW klystron developed for JLab by L-3 Communications, each new RF chain is a completely revamped system using hardware different than our present installations. This paper will discuss the main components of the new systems including the 13 kW klystron, waveguide isolator, and HV power supply using switch-mode technology. Methodology for selection of the various components and results of initial testing will also be addressed.

Slides THOCS4 [3.364 MB]

THP078

Study of a TeV Level Linear Collider Using Short rf Pulse (~20ns) Two Beam Accelerator Concept

collider, linear-collider, linac, wakefield

2279

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

Funding: Work is supported by DOE SBIR grant under contract No. DE-SC0004320.
In a general sense, a high gradient is desirable for a TeV level linear collider design because it can reduce the total linac length. More importantly, the efficiency and the cost to sustain such a gradient should be considered as well in the optimization process of an overall design. We propose a high energy linear collider based on a short rf pulse (~22ns flat top), high gradient (~267MV/m loaded gradient), high frequency (26GHz) dielectric two beam accelerator scheme. This scheme is a modular design and its unique locally repetitive drive beam structure allows a flexible configuration to meet different needs. Major parameters of a conceptual 3-TeV linear collider are presented. This preliminary study shows an efficient (~7% overall ) short pulse collider may be achievable. As the first step, a dielectric based broadband accelerating structure is under development.

THP124

Higher Current Operation for the APS Upgrade

HOM, cavity, lattice, feedback

2351

K.C. Harkay, G. Berenc, M. Borland, Y.-C. Chae, L. Emery, D. Horan, R. Nassiri, V. Sajaev, K.M. Schroeder, G.J. Waldschmidt, A. Xiao, C. Yao
ANL, Argonne, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source is a 7-GeV hard x-ray synchrotron light source. Operation for users is delivered at a nominal current of 100 mA in one of three bunch patterns. The APS Upgrade calls for a minimum planned operating current of 150 mA, with an option to deliver beam up to 200 mA. The high-current threshold in the storage ring has been explored, and storage ring components have been identified that either drive collective instabilities or are subjected to excessive beam-drive higher-order-mode (HOM) heating. In this paper, we describe machine studies at 150 mA in a special lattice that simulates the upgraded APS. We also describe the accelerator upgrades that are required to accommodate 200-mA operation, as well as the ongoing machine studies plan.

FROBS4

NSLS-II RF Systems

cavity, storage-ring, linac, coupling

2583

J. Rose, W.K. Gash, B. Holub, Y. Kawashima, H. Ma, N.A. Towne, M. Yeddulla
BNL, Upton, Long Island, New York, USA

The NSLS-II RF systems include solid state modulators for the S-band klystrons powering the traveling wave sections for the 200 MeV injector linac, 7 cell cavity with IOT amplifier for the 3 GeV booster synchrotron and superconducting 500 MHz cavities powered by klystrons and a passive 1500 MHz SRF cavity for the 3 GeV, 500 mA storage ring. The systems are controlled by digital I/Q modulators fed by an ultra-low noise master oscillator. System overviews will be given along with preliminary test data.

Slides FROBS4 [1.041 MB]