2011 Particle Accelerator Conference - List of Keywords (high-voltage)

Paper	Title	Other Keywords	Page
MOP017	A Sphere Cooler Scheme for Muon Cooling	collider, solenoid, factory, simulation	139
	Y. Bao MPI, Muenchen, Germany A. Caldwell, D. Greenwald MPI-P, München, Germany
	Muon cooling is the greatest obstacle for producing an intensive muon beam. The frictional cooling method holds promise for delivering low-energy muon beams with narrow energy spreads. We outline a sphere cooler scheme based on frictional cooling to effectively produce such a “cold” muon beam. As an example source, we take the parameters of a surface muon source available at the Paul Scherrer Institute. Simulation results show that the sphere cooler has an efficiency of 50% to produce a “cold” muon beam with an energy spread of 0.9 keV. The high quality beam can potentially meet the requirements of a neutrino factory or a muon collider.

MOP155	Progress on Diamond Amplified Photo Cathode	electron, gun, cathode, cavity	382
	E. Wang PKU/IHIP, Beijing, People's Republic of China I. Ben-Zvi, X. Chang, J. Kewisch, E.M. Muller, T. Rao, J. Smedley, Q. Wu BNL, Upton, Long Island, New York, USA T. Xin Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven science Associates, LLC Contract No.DE-AC02-98CH10886 with the U.S.DOE Two years ago, we obtained an emission gain of 40 from the Diamond Amplifier Cathode (DAC) in our test system. In our current systematic study of hydrogenation, the highest gain we registered in emission scanning was 178. We proved that our treatments for improving the diamond amplifiers are reproducible. Upcoming tests planned include testing DAC in a RF cavity. Already, we have designed a system for these tests using our 112 MHz superconducting cavity, wherein we will measure DAC parameters, such as the limit, if any, on emission current density, the bunch charge, and the bunch length.

MOP243	Design of a Compact, High-Resolution Analyzer for Longitudinal Energy Studies in the University of Maryland Electron Ring	focusing, simulation, space-charge, electron	571
	E.C. Voorhies, S. Bernal, I. Haber, R.A. Kishek, T.W. Koeth, P.G. O'Shea UMD, College Park, Maryland, USA
	Funding: Work supported by US Dept. of Energy Offices of High Energy Physics and Fusion Energy Sciences, the Dept. of Defense Office of Naval Research, and the Joint Technology Office. Retarding-potential energy analyzers have long been used for energy spread measurements in low-energy beams. In addition to energy spread and energy profile measurements, a high-resolution analyzer can be used to reconstruct the longitudinal phase space. This is useful for our experimental studies of longitudinal physics topics, such as dispersion, space charge waves, and longitudinal focusing. A previous energy analyzer designed at the University of Maryland demonstrated high-resolution measurements of a 5 keV electron beam.* Motivated by the need to characterize the 10 keV electron beam of the University of Maryland Electron Ring, we have improved on the design of the earlier analyzer, increasing its high voltage breakdown threshold and vacuum performance. Results of high-voltage testing and particle optics simulations of the new design are presented. *Y. Cui, Y. Zou, et al., "Design and Operation of a Retarding Field Energy Analyzer with Variable Focusing for Space-Charge Dominated Electron Beams," Review of Scientific Instruments 75(8), 2736 (2004).

MOP278	Ultra Precision Timing System for the Laser Megajoule	laser, diagnostics, target, plasma	633
	V. Drouet, M. Luttmann, M. Prat CEA, Arpajon, France
	This article presents a specific timing system designed for the Laser Megajoule project. This accuracy timing system has to deliver 64 electrical trigger signals with a very low jitter (< 5 ps rms) in order to synchronize the 240 laser pulses on the same target, in single shot mode and over 100 meter distances. After a dimensioning phase leading to the architecture of the system and the selection of components, a prototype was developed providing 8 electrical trigger signals. We expose the architecture and the excellent results achieved on this prototype regarding jitter, thermal drift and delay linearity.

TUP017	Conceptual Design for the ARIEL 300 keV Electron Gun	gun, electron, cathode, vacuum	847
	C.D. Beard, F. Ames, S. Austen, R.A. Baartman, Y.-C. Chao, K. Fong, C. Gong, N. Khan, S.R. Koscielniak, A. Laxdal, R.E. Laxdal, C.D.P. Levy, D. Louie, J. Lu, L. Merminga, A.K. Mitra, D. Rowbotham, P. Vincent, D. Yosifov TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada C.K. Sinclair CLASSE, Ithaca, New York, USA
	The Advanced Rare Isotope Laboratory (ARIEL) at TRIUMF is a facility that will augment existing programs at ISAC. ARIEL was funded in July 2010. Products from the complementary methods of proton-driven and bremsstrahlung-driven fission will be available for nuclear and materials science. Equipment for the photofission driver is the subject of this paper: a high-intensity electron beam provided by a high-voltage electron source (or e-gun) will be accelerated in a superconducting linear accelerator, and guided to a γ-ray convertor and actinide target assembly. The electron source is a 10 mA 300 keV thermionic gun, with a control grid for modulation of the beam. This paper describes the conceptual design of the gun, and highlights some of the progress made in the engineering design. First beam from the gun is anticipated in early 2012.

TUP073	Development of an L-band Ferroelectric Phase Shifter	simulation, insertion, controls, linac	955
	S. Kazakov, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA J.L. Hirshfield Yale University, Physics Department, New Haven, CT, USA A. Kanareykin, E. Nenasheva Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Shchelkunov Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
	Effective operation of the RF cavities in the superconducting accelerators demands fast, high-power RF vector modulators. Recent progress in development of the new materials, ferroelectrics, having tunable dielectric constant and acceptable losses [] gives the possibility development of such devises. In previous papers [-*] the authors described different L-band ferroelectric phase shifter designs . At low RF level high operation speed of 2 degree/nsec was demonstrated in waveguide phase shifter. However, the experiments show that a special technology is to be developed that provides a good electric contact between ceramics and the metallic wall. In present paper a new design of the fast high–power ferroelectric phase shifter is described based on the simple ferroelectric elements. A. Kanareykin, et al, IPAC 2010, p. 3987 S. Kazakov, et al, “Fast Ferroelectric Phase Shifter Design For ERLs,” 45th ICFA Beam Dynamics Workshop, 2009 * S. Kazakov, et al, PAC2007, p. 599.

TUP117	Solid State Direct Drive RF LINAC: High Power Experimental Program	cavity, impedance, controls, linac	1056
	T.J.S. Hughes, M. Back, R. Fleck, M. Hergt, R. Irsigler, T. Kluge, J. Sirtl Siemens AG, Erlangen, Germany O. Heid Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
	We report on a 150MHz λ/4 coaxial resonator driven by 32 integrated class F RF power modules according to our direct drive concept [1,2]. Electric fields of 60MV/m at the resonator gap have been reached, which correspond to 80kW RF power. This power level has been achieved at 160V DC supply voltage, significantly less than the component limits. The observed power and Q values can be explained by a simple equivalent circuit. The model predicts that 64 modules at 160V DC supply voltage may provide 170kW RF power, and that 250V DC supply voltage should yield 400kW. The corresponding 134MV/m gap E field may not be reachable due to vacuum flashover. * 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

TUP130	Experiments on Voltage Droop Compensation for High Power Marx Modulators	controls, factory, linac, simulation	1076
	P. Chen, M. Lundquist, D. Yu DULY Research Inc., Rancho Palos Verdes, California, USA
	Funding: Work supported by DOE SBIR Phase II grant DE-FG02-08ER85052 Marx modulators, promising higher efficiency, longer lifetime and reduced cost compared with existing hard tube modulator options, are under intensive research. In this article, we describe the progress of work on our voltage droop compensation scheme for a Marx modulator. Experimental results on a compensation circuit at moderate voltage are presented.

TUP132	50 MW X-Band RF System for a Photoinjector Test Station at LLNL	klystron, electron, linac, 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.

TUP213	Research and Development toward the RHIC Injection Kicker Upgrade	kicker, injection, factory, impedance	1211
	W. Zhang, W. Fischer, H. Hahn, C. Pai, J. Sandberg, J.E. Tuozzolo BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A research and development work is on going toward the upgrade of the RHIC Injection Fast Kicker System. We report here the proposed nano-second pulse generator, the initial test result, the options of the deflector design, injection pattern, and the benefit to the future RHIC programs.

TUP253	AGS Tune Jump Power Supply Design and Test	power-supply, controls, simulation, resonance	1298
	J.-L. Mi, J.W. Glenn, H. Huang, I. Marneris, P.J. Rosas, J. Sandberg, Y. Tan, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A horizontal tune jump system has been installed to overcome the horizontal intrinsic spin resonances, which requires jumping the horizontal tune 0.04 units 82 times, 41 up and 41 down. Two quadruple magnets have been installed in AGS ring to do this. The pulsed magnet currents range from about 140 amps near injection to about 1400 amps late. Current pulse rise and fall times are around 100 micro-sec and flat tops time are around 4mS. These quadruples have separate supplies. This tune jump pulse power supply employees all semiconductor parts as the main switches. During dummy load and magnet testing, the test result showed that the power supply could meet the specification. This article will describe some detail of power supply simulation, design and testing. Some test waveform and pictures are presented in this paper.

TUP255	Solid-State Transmitter for a 2 MW Klystron	controls, klystron, cathode, 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.

TUP256	Affordable, Short Pulse Marx Modulator	controls, pick-up, status, linear-collider	1307
	M.K. Kempkes, J.A. Casey, M.P.J. Gaudreau, R.A. Phillips Diversified Technologies, Inc., Bedford, Massachusetts, USA J. Casey Rockfield Research, Inc. east, Winchester, Massachusetts, USA
	Funding: U.S. Department of Energy Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) is developing a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 500 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort are modularity and scalablity, combined with low cost, and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are simply not available with hard switch or transformer-coupled topologies. In this paper, DTI will describe the new design and provide an update on progress.

TUP259	A Solid-State Nanosecond Beam Kicker Modulator Based on the DSRD Switch	kicker, extraction, status, impedance	1310
	A.L. Benwell, R. Akre, C. Burkhart, A. Krasnykh, T. Tang SLAC, Menlo Park, California, USA A. Kardo-Sysoev IOFFE, St. Petersburg, Russia
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 A fast solid-state beam kicker modulator is under development at the SLAC National Accelerator Laboratory. The program goal is to develop a modulator that will deliver 4 ns, ±5 kV pulses to the ATF2 damping ring beam extraction kicker. The kicker is a 50 Ω, bipolar strip line, 60 cm long, fed at the downstream end and terminated at the upstream end. The bunch spacing in the ring is 5.6 ns, bunches are removed from the back end of the train, and there is a gap of 10³.6 ns before the next train. The modulator design is based on an opening switch topology that uses Drift Step Recovery Diodes as the opening switches. The design and results of the modulator development are discussed.

TUP261	The ILC P2 Marx and Application of the Marx Topology to Future Accelerators	klystron, controls, power-supply, FEL	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, klystron, 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.

WEODS3	CEBAF 200 kV Inverted Electron Gun	laser, electron, vacuum, niobium	1501
	J.M. Grames, P.A. Adderley, J. Clark, J. Hansknecht, M. Poelker, M.L. Stutzman, R. Suleiman, K.E.L. Surles-Law JLAB, Newport News, Virginia, USA M. BastaniNejad Old Dominion University, Norfolk, Virginia, USA J.L. McCarter UVa, Charlottesville, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In addition, DOE-HEP funds this work in support of the ILC R&D program. Two DC high voltage GaAs photoguns have been built at Jefferson Lab based on a compact inverted insulator design. One photogun provides the polarized electron beam at CEBAF and operates at 130 kV bias voltage. The other gun is used for high average current lifetime studies at a dedicated test facility and has been operated at bias voltage up to 225 kV. The advantages of higher DC voltage for CEBAF include reduced space-charge emittance growth and the potential for prolonged photocathode lifetime. However, a consequence of operating at higher voltages is the increased likelihood of field emission or breakdown, both of which are unacceptable. Highlights of the R&D studies leading toward a production 200keV GaAs photogun for CEBAF will be presented.
	Slides WEODS3 [1.360 MB]

WEP207	Progress Towards A Novel Compact High Voltage Electrostatic Accelerator	vacuum, proton, tandem-accelerator, injection	1876
	P. Beasley, O. Heid Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
	A proof-of-principle demonstrator system has been successfully built and tested. It is based on a Cockcroft-Walton (or Greinacher) cascade but has been developed using a different design philosophy and using modern materials. This can then enable this compact accelerator configuration to operate at much higher voltage gradients. This paper explores the progress made to-date and future plans to utilize the technology to develop one such concept for an energy efficient 10 MV, 100 microamp, tandem proton accelerator, with less than a 2 square meter footprint .

WEP209	Reliability Study of the AIRIX Induction Accelerator over a Functioning Period of Ten Years (2000-2010)	electron, vacuum, diagnostics, controls	1882
	H. Dzitko, A. Georges, B. Gouin, M. Mouillet CEA, Pontfaverger-Moronvilliers, France
	AIRIX is a high current (19 MeV, 2 kA) electron linear induction accelerator used as a 60 ns single shot X-ray source for hydrodynamic experiments. As single shot experiments are performed with the AIRIX facility, the best performances and a high reliability level must be met for each experiment. A high availability is also a key issue for the successful development of hydrotest projects. The AIRIX accelerator has been running for hydroshot experiments since 2000 and several thousands electron and X-ray beams have been produced. This paper outlines the reliability results of the AIRIX accelerator over a functioning period of ten years. Failure rates for each main subsystems are shown : injector, accelerating cells, high voltage generators, and measurement chains. We also give an overview of the most probable faults, with the associated occurrence rates, which can alter the X source of the AIRIX machine over this ten year period.

WEP229	Status of 2 MeV Electron Cooler for COSY-Julich/HESR	electron, antiproton, proton, solenoid	1918
	J. Dietrich, V. Kamerdzhiev FZJ, Jülich, Germany M.I. Bryzgunov, A.D. Goncharov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov BINP SB RAS, Novosibirsk, Russia
	The 2 MeV electron cooling system for COSY-Jülich was proposed to further boost the luminosity even in presence of strong heating effects of high-density internal targets. The 2 MeV cooler is also well suited in the start up phase of the High Energy Storage Ring (HESR) at FAIR in Darmstadt. It can be used for beam cooling at injection energy and is intended to test new features of the high energy electron cooler for HESR. The project is funded since mid 2009. The design and construction of the cooler is accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The technical layout of the 2 MeV electron cooler is described. The infrastructure necessary for the operation of the cooler in the COSY ring (radiation shielding, cabling, water cooling etc.) is established. The electron beam commissioning at BINP Novosibirsk is scheduled to start at the end of 2010. First results are reported.

WEP284	Performance Study of K2CsSb Photocathode inside a DC High Voltage Gun	gun, laser, cathode, vacuum	2017
	T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA J.M. Grames, R.R. Mammei, J.L. McCarter, M. Poelker, R. Suleiman JLAB, Newport News, Virginia, USA
	Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grant DE-FG02-08ER41547. In the past decade, there has been considerable interest in the generation of tens of mA average current in a photoinjector. Until recently, GaAs:Cs cathodes and K2CsSb cathodes have been tested successfully in DC and RF injectors respectively for this application. Our goal is to test the GaAs:Cs in RF injector and the K2CsSb cathode in the DC gun in order to widen our choices. Since the multialkali cathode is a compound with uniform stochiometry over its entire thickness, we anticipate that the life time issues seen in GaAs:Cs due surface damage by ion bombardment would be minimized with this material. Hence successful operation of the K2CsSb cathode in DC gun could lead to a relatively robust electron source capable of delivering ampere level currents. In order to test the performance of K2CsSb cathode in a DC gun, we have designed and built a load lock system that would allow the fabrication of the cathode at BNL and its testing at JLab. In this paper, we will present the design of the load-lock system, cathode fabrication, and the cathode performance in the preparation chamber and in the DC gun.

WEP287	Field Emission Measurements from Niobium Electrodes	niobium, cathode, vacuum, SRF	2020
	M. BastaniNejad Old Dominion University, Norfolk, Virginia, USA P.A. Adderley, J. Clark, S. Covert, J. Hansknecht, C. Hernandez-Garcia, R.R. Mammei, M. Poelker JLAB, Newport News, Virginia, USA
	Increasing the operating voltage of a DC high voltage photogun serves to minimize space charge induced emittance growth and thereby preserve electron beam brightness, however, field emission from the photogun cathode electrode can pose significant problems: constant low level field emission degrades vacuum via electron stimulated desorption which in turn reduces photocathode yield through chemical poisoning and/or ion bombardment and high levels of field emission can damage the ceramic insulator. Niobium electrodes (single crystal, large grain and fine grain) were characterized using a DC high voltage field emission test stand at maximum voltage -225kV and electric field gradient > 10MV/m. Niobium electrodes appear to be superior to diamond-paste polished stainless steel electrodes.

THP108	Analysis of RHIC Beam Dump Pre-fires	radiation, kicker, survey, secondary-beams	2327
	W. Zhang, L. A. Ahrens, W. Fischer, H. Hahn, J.-L. Mi, J. Sandberg, Y. Tan BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. It has been speculated that the beam may cause instability of the RHIC Beam Abort Kickers. In this study, we explore the available data of past beam operations, the device history of key modulator components, and the radiation patterns to examine the correlations.

THP203	Improved Inverted DC Gun Insulator Assembly	gun, vacuum, power-supply	2501
	M.L. Neubauer, A. Dudas, R. Sah Muons, Inc, Batavia, USA
	Funding: Work supported in part by USDOE Contract No. DE-AC05-84-ER-40150. High gradient DC guns are currently being developed with inverted ceramic insulators in order to avoid failure of the insulators from field emission and charge build-up. Our goal is to increase the DC voltages from 250 kV to 500 kV in these inverted ceramic DC Gun insulator assemblies. To achieve reliability, the arc-path gradient along the length of the insulator ceramic at the interface with the dielectric material should be lower than 500 kV/m (13 V/mil). In order to achieve this low arc-path gradient, a novel extended inverted insulator ceramic is being developed. Novel assembly processes are being developed for the high voltage connector, so that the interface between the connector dielectric and the surface of the extended inverted ceramic insulator will be void free. A complete DC Gun Inverted Ceramic Insulator Assembly will be designed and fabricated for reliable 500 kV DC operation.

Paper

Title

Other Keywords

Page

MOP017

A Sphere Cooler Scheme for Muon Cooling

collider, solenoid, factory, simulation

139

Y. Bao
MPI, Muenchen, Germany
A. Caldwell, D. Greenwald
MPI-P, München, Germany

Muon cooling is the greatest obstacle for producing an intensive muon beam. The frictional cooling method holds promise for delivering low-energy muon beams with narrow energy spreads. We outline a sphere cooler scheme based on frictional cooling to effectively produce such a “cold” muon beam. As an example source, we take the parameters of a surface muon source available at the Paul Scherrer Institute. Simulation results show that the sphere cooler has an efficiency of 50% to produce a “cold” muon beam with an energy spread of 0.9 keV. The high quality beam can potentially meet the requirements of a neutrino factory or a muon collider.

MOP155

Progress on Diamond Amplified Photo Cathode

electron, gun, cathode, cavity

382

E. Wang
PKU/IHIP, Beijing, People's Republic of China
I. Ben-Zvi, X. Chang, J. Kewisch, E.M. Muller, T. Rao, J. Smedley, Q. Wu
BNL, Upton, Long Island, New York, USA
T. Xin
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven science Associates, LLC Contract No.DE-AC02-98CH10886 with the U.S.DOE
Two years ago, we obtained an emission gain of 40 from the Diamond Amplifier Cathode (DAC) in our test system. In our current systematic study of hydrogenation, the highest gain we registered in emission scanning was 178. We proved that our treatments for improving the diamond amplifiers are reproducible. Upcoming tests planned include testing DAC in a RF cavity. Already, we have designed a system for these tests using our 112 MHz superconducting cavity, wherein we will measure DAC parameters, such as the limit, if any, on emission current density, the bunch charge, and the bunch length.

MOP243

Design of a Compact, High-Resolution Analyzer for Longitudinal Energy Studies in the University of Maryland Electron Ring

focusing, simulation, space-charge, electron

571

E.C. Voorhies, S. Bernal, I. Haber, R.A. Kishek, T.W. Koeth, P.G. O'Shea
UMD, College Park, Maryland, USA

Funding: Work supported by US Dept. of Energy Offices of High Energy Physics and Fusion Energy Sciences, the Dept. of Defense Office of Naval Research, and the Joint Technology Office.
Retarding-potential energy analyzers have long been used for energy spread measurements in low-energy beams. In addition to energy spread and energy profile measurements, a high-resolution analyzer can be used to reconstruct the longitudinal phase space. This is useful for our experimental studies of longitudinal physics topics, such as dispersion, space charge waves, and longitudinal focusing. A previous energy analyzer designed at the University of Maryland demonstrated high-resolution measurements of a 5 keV electron beam.* Motivated by the need to characterize the 10 keV electron beam of the University of Maryland Electron Ring, we have improved on the design of the earlier analyzer, increasing its high voltage breakdown threshold and vacuum performance. Results of high-voltage testing and particle optics simulations of the new design are presented.
*Y. Cui, Y. Zou, et al., "Design and Operation of a Retarding Field Energy Analyzer with Variable Focusing for Space-Charge Dominated Electron Beams," Review of Scientific Instruments 75(8), 2736 (2004).

MOP278

Ultra Precision Timing System for the Laser Megajoule

laser, diagnostics, target, plasma

633

V. Drouet, M. Luttmann, M. Prat
CEA, Arpajon, France

This article presents a specific timing system designed for the Laser Megajoule project. This accuracy timing system has to deliver 64 electrical trigger signals with a very low jitter (< 5 ps rms) in order to synchronize the 240 laser pulses on the same target, in single shot mode and over 100 meter distances. After a dimensioning phase leading to the architecture of the system and the selection of components, a prototype was developed providing 8 electrical trigger signals. We expose the architecture and the excellent results achieved on this prototype regarding jitter, thermal drift and delay linearity.

TUP017

Conceptual Design for the ARIEL 300 keV Electron Gun

gun, electron, cathode, vacuum

847

C.D. Beard, F. Ames, S. Austen, R.A. Baartman, Y.-C. Chao, K. Fong, C. Gong, N. Khan, S.R. Koscielniak, A. Laxdal, R.E. Laxdal, C.D.P. Levy, D. Louie, J. Lu, L. Merminga, A.K. Mitra, D. Rowbotham, P. Vincent, D. Yosifov
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
C.K. Sinclair
CLASSE, Ithaca, New York, USA

The Advanced Rare Isotope Laboratory (ARIEL) at TRIUMF is a facility that will augment existing programs at ISAC. ARIEL was funded in July 2010. Products from the complementary methods of proton-driven and bremsstrahlung-driven fission will be available for nuclear and materials science. Equipment for the photofission driver is the subject of this paper: a high-intensity electron beam provided by a high-voltage electron source (or e-gun) will be accelerated in a superconducting linear accelerator, and guided to a γ-ray convertor and actinide target assembly. The electron source is a 10 mA 300 keV thermionic gun, with a control grid for modulation of the beam. This paper describes the conceptual design of the gun, and highlights some of the progress made in the engineering design. First beam from the gun is anticipated in early 2012.

TUP073

Development of an L-band Ferroelectric Phase Shifter

simulation, insertion, controls, linac

955

S. Kazakov, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
A. Kanareykin, E. Nenasheva
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA

Effective operation of the RF cavities in the superconducting accelerators demands fast, high-power RF vector modulators. Recent progress in development of the new materials, ferroelectrics, having tunable dielectric constant and acceptable losses [*] gives the possibility development of such devises. In previous papers [**-***] the authors described different L-band ferroelectric phase shifter designs . At low RF level high operation speed of 2 degree/nsec was demonstrated in waveguide phase shifter. However, the experiments show that a special technology is to be developed that provides a good electric contact between ceramics and the metallic wall. In present paper a new design of the fast high–power ferroelectric phase shifter is described based on the simple ferroelectric elements.
* A. Kanareykin, et al, IPAC 2010, p. 3987
** S. Kazakov, et al, “Fast Ferroelectric Phase Shifter Design For ERLs,” 45th ICFA Beam Dynamics Workshop, 2009
*** S. Kazakov, et al, PAC2007, p. 599.

TUP117

Solid State Direct Drive RF LINAC: High Power Experimental Program

cavity, impedance, controls, linac

1056

T.J.S. Hughes, M. Back, R. Fleck, M. Hergt, R. Irsigler, T. Kluge, J. Sirtl
Siemens AG, Erlangen, Germany
O. Heid
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany

We report on a 150MHz λ/4 coaxial resonator driven by 32 integrated class F RF power modules according to our direct drive concept [1,2]. Electric fields of 60MV/m at the resonator gap have been reached, which correspond to 80kW RF power. This power level has been achieved at 160V DC supply voltage, significantly less than the component limits. The observed power and Q values can be explained by a simple equivalent circuit. The model predicts that 64 modules at 160V DC supply voltage may provide 170kW RF power, and that 250V DC supply voltage should yield 400kW. The corresponding 134MV/m gap E field may not be reachable due to vacuum flashover.
* 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

TUP130

Experiments on Voltage Droop Compensation for High Power Marx Modulators

controls, factory, linac, simulation

1076

P. Chen, M. Lundquist, D. Yu
DULY Research Inc., Rancho Palos Verdes, California, USA

Funding: Work supported by DOE SBIR Phase II grant DE-FG02-08ER85052
Marx modulators, promising higher efficiency, longer lifetime and reduced cost compared with existing hard tube modulator options, are under intensive research. In this article, we describe the progress of work on our voltage droop compensation scheme for a Marx modulator. Experimental results on a compensation circuit at moderate voltage are presented.

TUP132

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

klystron, electron, linac, 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.

TUP213

Research and Development toward the RHIC Injection Kicker Upgrade

kicker, injection, factory, impedance

1211

W. Zhang, W. Fischer, H. Hahn, C. Pai, J. Sandberg, J.E. Tuozzolo
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A research and development work is on going toward the upgrade of the RHIC Injection Fast Kicker System. We report here the proposed nano-second pulse generator, the initial test result, the options of the deflector design, injection pattern, and the benefit to the future RHIC programs.

TUP253

AGS Tune Jump Power Supply Design and Test

power-supply, controls, simulation, resonance

1298

J.-L. Mi, J.W. Glenn, H. Huang, I. Marneris, P.J. Rosas, J. Sandberg, Y. Tan, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A horizontal tune jump system has been installed to overcome the horizontal intrinsic spin resonances, which requires jumping the horizontal tune 0.04 units 82 times, 41 up and 41 down. Two quadruple magnets have been installed in AGS ring to do this. The pulsed magnet currents range from about 140 amps near injection to about 1400 amps late. Current pulse rise and fall times are around 100 micro-sec and flat tops time are around 4mS. These quadruples have separate supplies. This tune jump pulse power supply employees all semiconductor parts as the main switches. During dummy load and magnet testing, the test result showed that the power supply could meet the specification. This article will describe some detail of power supply simulation, design and testing. Some test waveform and pictures are presented in this paper.

TUP255

Solid-State Transmitter for a 2 MW Klystron

controls, klystron, cathode, 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.

TUP256

Affordable, Short Pulse Marx Modulator

controls, pick-up, status, linear-collider

1307

M.K. Kempkes, J.A. Casey, M.P.J. Gaudreau, R.A. Phillips
Diversified Technologies, Inc., Bedford, Massachusetts, USA
J. Casey
Rockfield Research, Inc. east, Winchester, Massachusetts, USA

Funding: U.S. Department of Energy
Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) is developing a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 500 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort are modularity and scalablity, combined with low cost, and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are simply not available with hard switch or transformer-coupled topologies. In this paper, DTI will describe the new design and provide an update on progress.

TUP259

A Solid-State Nanosecond Beam Kicker Modulator Based on the DSRD Switch

kicker, extraction, status, impedance

1310

A.L. Benwell, R. Akre, C. Burkhart, A. Krasnykh, T. Tang
SLAC, Menlo Park, California, USA
A. Kardo-Sysoev
IOFFE, St. Petersburg, Russia

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515
A fast solid-state beam kicker modulator is under development at the SLAC National Accelerator Laboratory. The program goal is to develop a modulator that will deliver 4 ns, ±5 kV pulses to the ATF2 damping ring beam extraction kicker. The kicker is a 50 Ω, bipolar strip line, 60 cm long, fed at the downstream end and terminated at the upstream end. The bunch spacing in the ring is 5.6 ns, bunches are removed from the back end of the train, and there is a gap of 10³.6 ns before the next train. The modulator design is based on an opening switch topology that uses Drift Step Recovery Diodes as the opening switches. The design and results of the modulator development are discussed.

TUP261

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

klystron, controls, power-supply, FEL

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, klystron, 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.

WEODS3

CEBAF 200 kV Inverted Electron Gun

laser, electron, vacuum, niobium

1501

J.M. Grames, P.A. Adderley, J. Clark, J. Hansknecht, M. Poelker, M.L. Stutzman, R. Suleiman, K.E.L. Surles-Law
JLAB, Newport News, Virginia, USA
M. BastaniNejad
Old Dominion University, Norfolk, Virginia, USA
J.L. McCarter
UVa, Charlottesville, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In addition, DOE-HEP funds this work in support of the ILC R&D program.
Two DC high voltage GaAs photoguns have been built at Jefferson Lab based on a compact inverted insulator design. One photogun provides the polarized electron beam at CEBAF and operates at 130 kV bias voltage. The other gun is used for high average current lifetime studies at a dedicated test facility and has been operated at bias voltage up to 225 kV. The advantages of higher DC voltage for CEBAF include reduced space-charge emittance growth and the potential for prolonged photocathode lifetime. However, a consequence of operating at higher voltages is the increased likelihood of field emission or breakdown, both of which are unacceptable. Highlights of the R&D studies leading toward a production 200keV GaAs photogun for CEBAF will be presented.

Slides WEODS3 [1.360 MB]

WEP207

Progress Towards A Novel Compact High Voltage Electrostatic Accelerator

vacuum, proton, tandem-accelerator, injection

1876

P. Beasley, O. Heid
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany

A proof-of-principle demonstrator system has been successfully built and tested. It is based on a Cockcroft-Walton (or Greinacher) cascade but has been developed using a different design philosophy and using modern materials. This can then enable this compact accelerator configuration to operate at much higher voltage gradients. This paper explores the progress made to-date and future plans to utilize the technology to develop one such concept for an energy efficient 10 MV, 100 microamp, tandem proton accelerator, with less than a 2 square meter footprint .

WEP209

Reliability Study of the AIRIX Induction Accelerator over a Functioning Period of Ten Years (2000-2010)

electron, vacuum, diagnostics, controls

1882

H. Dzitko, A. Georges, B. Gouin, M. Mouillet
CEA, Pontfaverger-Moronvilliers, France

AIRIX is a high current (19 MeV, 2 kA) electron linear induction accelerator used as a 60 ns single shot X-ray source for hydrodynamic experiments. As single shot experiments are performed with the AIRIX facility, the best performances and a high reliability level must be met for each experiment. A high availability is also a key issue for the successful development of hydrotest projects. The AIRIX accelerator has been running for hydroshot experiments since 2000 and several thousands electron and X-ray beams have been produced. This paper outlines the reliability results of the AIRIX accelerator over a functioning period of ten years. Failure rates for each main subsystems are shown : injector, accelerating cells, high voltage generators, and measurement chains. We also give an overview of the most probable faults, with the associated occurrence rates, which can alter the X source of the AIRIX machine over this ten year period.

WEP229

Status of 2 MeV Electron Cooler for COSY-Julich/HESR

electron, antiproton, proton, solenoid

1918

J. Dietrich, V. Kamerdzhiev
FZJ, Jülich, Germany
M.I. Bryzgunov, A.D. Goncharov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov
BINP SB RAS, Novosibirsk, Russia

The 2 MeV electron cooling system for COSY-Jülich was proposed to further boost the luminosity even in presence of strong heating effects of high-density internal targets. The 2 MeV cooler is also well suited in the start up phase of the High Energy Storage Ring (HESR) at FAIR in Darmstadt. It can be used for beam cooling at injection energy and is intended to test new features of the high energy electron cooler for HESR. The project is funded since mid 2009. The design and construction of the cooler is accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The technical layout of the 2 MeV electron cooler is described. The infrastructure necessary for the operation of the cooler in the COSY ring (radiation shielding, cabling, water cooling etc.) is established. The electron beam commissioning at BINP Novosibirsk is scheduled to start at the end of 2010. First results are reported.

WEP284

Performance Study of K2CsSb Photocathode inside a DC High Voltage Gun

gun, laser, cathode, vacuum

2017

T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA
J.M. Grames, R.R. Mammei, J.L. McCarter, M. Poelker, R. Suleiman
JLAB, Newport News, Virginia, USA

Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grant DE-FG02-08ER41547.
In the past decade, there has been considerable interest in the generation of tens of mA average current in a photoinjector. Until recently, GaAs:Cs cathodes and K2CsSb cathodes have been tested successfully in DC and RF injectors respectively for this application. Our goal is to test the GaAs:Cs in RF injector and the K2CsSb cathode in the DC gun in order to widen our choices. Since the multialkali cathode is a compound with uniform stochiometry over its entire thickness, we anticipate that the life time issues seen in GaAs:Cs due surface damage by ion bombardment would be minimized with this material. Hence successful operation of the K2CsSb cathode in DC gun could lead to a relatively robust electron source capable of delivering ampere level currents. In order to test the performance of K2CsSb cathode in a DC gun, we have designed and built a load lock system that would allow the fabrication of the cathode at BNL and its testing at JLab. In this paper, we will present the design of the load-lock system, cathode fabrication, and the cathode performance in the preparation chamber and in the DC gun.

WEP287

Field Emission Measurements from Niobium Electrodes

niobium, cathode, vacuum, SRF

2020

M. BastaniNejad
Old Dominion University, Norfolk, Virginia, USA
P.A. Adderley, J. Clark, S. Covert, J. Hansknecht, C. Hernandez-Garcia, R.R. Mammei, M. Poelker
JLAB, Newport News, Virginia, USA

Increasing the operating voltage of a DC high voltage photogun serves to minimize space charge induced emittance growth and thereby preserve electron beam brightness, however, field emission from the photogun cathode electrode can pose significant problems: constant low level field emission degrades vacuum via electron stimulated desorption which in turn reduces photocathode yield through chemical poisoning and/or ion bombardment and high levels of field emission can damage the ceramic insulator. Niobium electrodes (single crystal, large grain and fine grain) were characterized using a DC high voltage field emission test stand at maximum voltage -225kV and electric field gradient > 10MV/m. Niobium electrodes appear to be superior to diamond-paste polished stainless steel electrodes.

THP108

Analysis of RHIC Beam Dump Pre-fires

radiation, kicker, survey, secondary-beams

2327

W. Zhang, L. A. Ahrens, W. Fischer, H. Hahn, J.-L. Mi, J. Sandberg, Y. Tan
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
It has been speculated that the beam may cause instability of the RHIC Beam Abort Kickers. In this study, we explore the available data of past beam operations, the device history of key modulator components, and the radiation patterns to examine the correlations.

THP203

Improved Inverted DC Gun Insulator Assembly

gun, vacuum, power-supply

2501

M.L. Neubauer, A. Dudas, R. Sah
Muons, Inc, Batavia, USA

Funding: Work supported in part by USDOE Contract No. DE-AC05-84-ER-40150.
High gradient DC guns are currently being developed with inverted ceramic insulators in order to avoid failure of the insulators from field emission and charge build-up. Our goal is to increase the DC voltages from 250 kV to 500 kV in these inverted ceramic DC Gun insulator assemblies. To achieve reliability, the arc-path gradient along the length of the insulator ceramic at the interface with the dielectric material should be lower than 500 kV/m (13 V/mil). In order to achieve this low arc-path gradient, a novel extended inverted insulator ceramic is being developed. Novel assembly processes are being developed for the high voltage connector, so that the interface between the connector dielectric and the surface of the extended inverted ceramic insulator will be void free. A complete DC Gun Inverted Ceramic Insulator Assembly will be designed and fabricated for reliable 500 kV DC operation.