IPAC2012 - List of Keywords (high-voltage)

Paper	Title	Other Keywords	Page
MOPPD006	Commissioning of the 2MeV Electron Cooler for COSY / HESR	electron, solenoid, gun, laser	379
	V. Kamerdzhiev, J. Dietrich FZJ, Jülich, Germany V.N. Bocharov, M.I. Bryzgunov, A.D. Goncharov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov BINP SB RAS, Novosibirsk, Russia
	The new electron cooler for COSY is built at BINP Novosibirsk. Electron beam commissioning is in progress. Installation in COSY and commissioning with proton beam is scheduled for the beginning of 2012. Beam cooling with up to 3 A of electron current at up to 2 MeV is expected to boost the luminosity in the entire energy range of COSY by counteracting the effects caused by dense targets interacting with the circulating beam. Furthermore, the 2 MeV electron cooler can be used for beam cooling at injection energy in the HESR ring in the FAIR project. The electron beam is guided by a solenoidal magnetic field all the way from the electron gun to the collector. A cascade transformer provides power to numerous high voltage sections, short solenoids, and the collector inside a pressure vessel filed with SF6 gas. Commissioning results are reported.

MOPPD045	Performance Study of the PEFP Microwave Ion Source with Modified Microwave System	ion-source, ion, proton, linac	463
	D.I. Kim, Y.-S. Cho, H.S. Kim, H.-J. Kwon, K.T. Seol KAERI, Daejon, Republic of Korea
	Funding: This work is supported by the Ministry of Science and Technology of the Korean government. A microwave ion source has been developed as a proton injector for the Proton Engineering Frontier Project (PEFP) 100-MeV proton linac. The microwave ion source consists of the 2.45-GHz microwave components, a solenoid magnet, a vacuum system, power supplies for beam extraction and bias electrode, a cooling system. It was operating for 1 year to supply beam to the 20-MeV proton accelerator. Recently, a multi-layer insulation DC break was installed between proton source and 2.45-GHz microwave components. Also, the magnetron was replaced with lower saturation power level. The tests of the microwave system have been done to study the effect of the DC break and new magnetron compared with the former one. Also, the beam test was done after the operating conditions of the microwave system were adjusted. In this paper, the performance studies of the PEFP microwave ion source with DC break and new magnetron are discussed.

MOPPD053	Reduction of Outgassing from the Ferrite Cores in the Kicker Magnet of J-PARC RCS	vacuum, kicker, beam-transport, proton	487
	N. Ogiwara, Y. Hikichi, J. Kamiya, M. Kinsho, M. Nishikawa, K. Suganuma, T. Yanagibashi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Kicker magnets are used to kick out the accelerated beam to the beam transport lines in the RCS of the J-PARC. A high voltage is applied to kickers for a short period, so they must be installed in a vacuum to prevent discharge. Therefore, it is important to reduce the outgassing of water vapor from the ferrite cores. After bake-out at 200°C for 300 hours, the outgassing rate decreased to less than 1×10^-7 Pam/s. However, the small amount of water vapor and carbon monoxide were emitted from the ferrite cores at charging voltage of 80 kV. This time, we have decided to construct the reserve magnets with very low outgassing at high-voltage discharge. First of all, the thermal desorption behavior of the ferrite was investigated. Water vapor has two peaks: at ~ 100°C and 350°C. Carbon monoxide is rather largely emitted until 300°C. From these results, the ferrite cores were vacuum-fired at 450°C for 10 h. Then the good properties for the magnetic cores were confirmed. And now the assembling of the kicker magnet is undertaken. The performance of the kicker magnet made of the vacuum-fired ferrite will be shown in this meeting.

MOPPR043	Design, Construction and Calibration of a First Prototype of Beam Position System for Hadron Therapy Facilities	controls, proton, vacuum, power-supply	876
	A. Faus-Golfe, C. Belver-Aguilar, C. Blanch Gutierrez, J.J. García-Garrigós IFIC, Valencia, Spain E. Benveniste, M. Haguenauer, P. Poilleux LLR, Palaiseau, France
	Funding: AIC10-D-000518 and AIC-D-2011-0673. Beam Position Monitors (BPM) are essential elements in the instrumentation for the beam control in hadron therapy accelerators. The measurement of the beam position become more important at the secondary transport lines towards the patient room where this parameter must be completely determined. In this paper we describe the design, construction, read-out electronics and first calibration tests of a new type of BPM based on four scintillating fibers coupled to four photodiodes to detect the light produced by the fibers when intercepting the beam tails. The prototype will serve to evaluate the different design options in the mechanical and the read-out electronics implementation as well as to define the best processing method to get the beam position.

TUPPD050	Investigation of Laser-cleaning Process on Lead Photocathodes	laser, electron, cathode, photon	1515
	S.G. Schubert, R. Barday, T. Kamps, T. Quast, A. Varykhalov HZB, Berlin, Germany R. Nietubyć The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland F. Siewert BESSY GmbH, Berlin, Germany J. Smedley BNL, Upton, Long Island, New York, USA G. Weinberg FHI, Berlin, Germany
	Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin. Metal photocathodes are widely used in electron injectors due to their stability and long life time; unfortunately they exhibit low quantum efficiency. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is further reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley. The process was studied on witness samples in a combined photo emission, SEM and quantum efficiency measurement study. Thin Lead films were arc-deposited on optical polished Mo-substrates. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. We followed the change of the Pb 5d signals. In the initial situation we observed signals originating from metallic Pb and Pb in the oxidized state, respectively. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM. J. Smedley et al, PRST-AB 11, 013502 (2008). ** Rao, T. et al., IPAC 2010, THPEC020 (2010).

TUPPD081	Development of Carbon NanoTube (CNT) Cathodes at RadiaBeam	cathode, vacuum, gun, electron	1590
	L. Faillace, R.B. Agustsson, S. Boucher, A.Y. Murokh, A.V. Smirnov RadiaBeam, Santa Monica, USA
	RadiaBeam is developing Carbon Nanotube (CNT) cathodes for DC-pulsed and radio frequency (RF) driven electron sources. CNT cathodes, if realized, are capable of producing very high current density with low thermal emittance, due to ambient operating temperature. The initial experimental results of CNT cathodes are presented, including the high-voltage tests, and life time studies. CNT cathodes potential applications in accelerator science and microwave industry are discussed, and near term plans to test the CNT cathodes in the RF environment are presented.

WEPPC027	A Quarter Wave Design for Crab Crossing in the LHC	cavity, HOM, acceleration, higher-order-mode	2260
	R. Calaga CERN, Geneva, Switzerland S.A. Belomestnykh, I. Ben-Zvi, Q. Wu BNL, Upton, Long Island, New York, USA
	Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP). The aperture constraints of the LHC interaction region and the alternating crossing schemes at two collision points calls for a superconducting deflecting cavity with very compact dimensions at low frequencies for the purpose of crab crossing. A new concept of using a superconducting 1/4-wave design, ideally suited to address the LHC constraints at 400 MHz, is proposed. The optimized RF cavity design and associated advantages of using a 1/4 wave resonator are presented. Aspects related to higher order mode damping, multipacting and frequency tuning are also addressed.

WEPPD062	Measurements of the First RF Prototype of the Spiral2 Single Bunch Selector	vacuum, impedance, scattering, simulation	2663
	M. Di Giacomo GANIL, Caen, France A.C. Caruso, F. Consoli, G. Gallo, D. Rifuggiato, E. Zappalà INFN/LNS, Catania, Italy A. Longhitano ALTEK, San Gregorio (CATANIA), Italy
	Funding: Work supported by EU commission 7th framework project n. 212692. The single bunch selector of the Spiral2 driver uses 100 Ω travelling wave electrodes driven by fast pulse generators. A 2.5 kV, 1 kW feed-through and a vacuum chamber housing the water cooled electrodes have been designed and built. The paper reviews the whole design and reports the results of first RF and power measurements.

THAP01	Secondary-electron Emission from Hydrogen-terminated Diamond	electron, vacuum, linac, simulation	3223
	E. Wang, I. Ben-Zvi, T. Rao, Q. Wu BNL, Upton, Long Island, New York, USA D.A. Dimitrov Tech-X, Boulder, Colorado, USA T. Xin Stony Brook University, Stony Brook, USA
	Diamond amplifiers demonstrably are an electron source with the potential to support high-brightness, high-average-current emission into a vacuum. We recently developed a reliable hydrogenation procedure for the diamond amplifier. The systematic study of hydrogenation resulted in the reproducible fabrication of high gain diamond amplifier. Furthermore, we measured the emission probability of diamond amplifier as a function of the external field and modeled the process with resulting changes in the vacuum level due to the Schottky effect. We demonstrated that the decrease in the secondary electrons’ average emission gain was a function of the pulse width and related this to the trapping of electrons by the effective NEA surface. The findings from the model agree well with our experimental measurements. As an application of the model, the energy spread of secondary electrons inside the diamond was estimated from the measured emission.
	Slides THAP01 [2.034 MB]

THPPC016	PLSII Linac RF Conditioning Status	linac, klystron, storage-ring, vacuum	3311
	H.-S. Lee, J.Y. Huang, W.H. Hwang, H.-G. Kim, K.R. Kim, S.H. Kim, S.H. Kim, S.H. Nam, W. Namkung, S.S. Park, S.J. Park, Y.J. Park, S. Shin PAL, Pohang, Kyungbuk, Republic of Korea
	PLS linac has been upgraded in energy from 2.5 to 3.0 GeV. A klystron supplies RF power of 80 MW four acceleration structures through a SLED. But our machine is not enough RF power to get 3 GeV beam energy. So we have changed the RF scheme in four modules as a klystron supplies RF power of 80 MW two accelerating structures through a SLED. There were several problems during the RF conditioning and beam operation. So we will describe the conditioning results and the current status in this paper.

THPPC048	Innovative Low-Energy Ultra-Fast Electron Diffraction (UED) System	electron, cathode, gun, vacuum	3395
	L. Faillace, S. Boucher RadiaBeam, Santa Monica, USA P. Musumeci UCLA, Los Angeles, California, USA
	Funding: Work supported by DOE. RadiaBeam, in collaboration with UCLA, is developing an innovative, inexpensive, low-energy ultra-fast electron diffraction (UED) system which allows us to reconstruct a single ultrafast event with a single pulse of electrons. Time resolved measurement of atomic motion is one of the frontiers of modern science, and advancements in this area will greatly improve our understanding of the basic processes in materials science, chemistry and biology. The high-frequency (GHz), high voltage, phase-locked RF field in the deflector allows temporal resolution as fine as 100 fs. In this paper, we show the complete design of a UED system based on this concept, including an optimized electron gun, a high-resolution RF deflector, and the post-interaction imaging system.

THPPC060	Commissioning of the First Klystron-based X-band Power Source at CERN	klystron, vacuum, controls, low-level-rf	3428
	J.W. Kovermann, N. Catalan-Lasheras, S. Curt, S. Döbert, G. McMonagle, S.F. Rey, G. Riddone, K.M. Schirm, I. Syratchev, L. Timeo CERN, Geneva, Switzerland J.P. Eichner, A.A. Haase, D.W. Sprehn SLAC, Menlo Park, California, USA A. Hamdi, F. Peauger CEA/DSM/IRFU, France
	A new klystron based x-band rf power source working at 11.994GHz has been installed and commissioned at CERN in collaboration with CEA Saclay and SLAC for CLIC accelerating structure tests. The system comprises a solid state high voltage modulator, an XL5 klystron developed by SLAC, a cavity based SLED type pulse compressor, the necessary low level rf system including rf diagnostics and interlocks and the surrounding vacuum, cooling and controls infrastructure. The klystron can produce up to 50MW rf pulses of 1500ns pulse width and 50Hz repetition rate. After pulse compression, up to 100MW of rf power at 250ns pulse with are available in the structure test bunker. This paper describes in more detail this setup and the results of the commissioning which was necessary to arrive at the mentioned performance.

THPPC073	Development of the Energy-Efficient Solid State RF Power Source for the Jefferson Laboratory CEBAF Linac	controls, klystron, linac, insertion	3455
	X. Chang, N. Barov, D.J. Newsham, D. Wu Far-Tech, Inc., San Diego, California, USA
	Funding: Work supported by DOE Office of Nuclear Physics, DOE-SBIR #DE-SC0002529 We present the current status of FAR-TECH's Solid State RF Power Source for the Jefferson Laboratory CEBAF Linac. This power source design features up to 8 kW CW RF output power, GaN amplifier stages with high efficiency (>60%), and a compact design to fit existing rack space and cooling requirements at the installation site. We have finished most of the designs and have performed successfully the most critical tests of this project, the 4 to 1 combiner test and the cooling test. FAR-TECH’s solid state amplifier design has high efficiency, a wide range of design frequency (DC-3GHz), and long lifetime, which provides a good RF power source.

THPPD053	Study on Eddy Current Power Losses in Insulated Core Transformer Primary Coil	induction, power-supply, factory, simulation	3632
	L. Yang, X. Liu, Y.Q. Xiong, J. Yang Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China T. Yu HUST, Wuhan, People's Republic of China
	Insulated core transformer (ICT) high-voltage DC power supply is widely used in electron beam accelerator. With air gap in ICT, the reluctance of magnetic circuit is larger than other transformers, and the transverse magnetic flux leakage around the primary coil is more serious. Because the magnetic flux on the radial direction of coil cannot be ignored, the eddy current loss on the wire should be discussed. In this paper, simulation and analysis of the eddy current loss is presented. The relationship between the sizes of the coil wire is also discussed. An optimal design of the primary coil is shown.

THPPD056	Performance of the Crowbar of the LHC High Power RF System	klystron, proton, power-supply, controls	3641
	G. Ravida, O. Brunner, D. Valuch CERN, Geneva, Switzerland
	During operation, the LHC high power RF equipment such as klystrons, circulators, waveguides and couplers have to be protected from damage caused by electromagnetic discharges. Once ignited, these arcs grow over the full height of the waveguide and travel towards the RF source. The burning plasma can cause serious damage to the metal surfaces or ferrite materials. The "crowbar" protection system consists of an arc current detector coupled with a fast high voltage switch in order to rapidly discharge the main high voltage components such as cables and capacitors and to shut down the high voltage source. The existing protection system, which uses a thyratron for grounding the high voltage circuit, has been installed in the LHC about 20 years ago. The problem of "faulty shots" appears due to the higher energy of LHC compared to LEP, which may lead to unnecessary stops of the LHC due to the crowbar system. This paper presents two approaches under consideration to improve the thyratron’s performance and to use a solid state thyristor in high energy environment. The main objectives will be dissipate as little energy as possible in the arc and avoid "faulty shots".
	Poster THPPD056 [0.703 MB]

THPPD058	Reduction of Conductive EMI Noise Resulted from the Commercial Power Supply	power-supply, vacuum, impedance, coupling	3644
	C.S. Chen, C.K. Chan, J.-C. Chang, Y.L. Chu, K.H. Hsu, C.Y. Kuo, Y.-H. Liu, C.S. Yang NSRRC, Hsinchu, Taiwan
	Almost every electronic equipment must be connected to power system. Because of the complexity of power lines, the reduction of conductive electro-magnetic interference (C-EMI) plays an important role in precise measurements. In this paper, a line impedance stabilization network (LISN) was built up to get the spectrum from power lines. After several measurements by some commercial power supplies, it is found that some of these power supplies induce effectively C-EMI into power lines, even if a passive filter is bound in power line. These noises may influence numerous equipments in a local area near the sources. Therefore, how to choose a suitable filter is a decisive factor to reduce the magnitude of C-EMI.

THPPD069	Adjustable Pulse Duration Fast Kicker for the CRYRING Storage Ring	kicker, extraction, injection, controls	3671
	J.-P. Lavieville, P. Lebasque SOLEIL, Gif-sur-Yvette, France W. Beeckman, O. Cosson Sigmaphi, Vannes, France
	The CRYRING storage ring of the Manne Siegbahn Laboratory (MSL, Stockholm) shall be moved to become part of FLAIR accelerators complex in Darmstadt to be used for deceleration of antiprotons and charged ions. That needs an upgrade to adapt it to the full energy range (30MeV – 0.13 MeV) of its future exploitation. SIGMAPHI, in close collaboration with SOLEIL light Source, is in charge of new fast injection and extraction magnets kickers and their pulsed power supplies. The injection will be done at maximum energy (30 MeV) while the extraction need to cover the full energy range (30 MeV – 0.13 MeV) that requires a continuous adjustment capability on the pulse duration and on the deviation amplitude. The development made specifically for the CRYRING kickers is based on a new design involving two different pulsed power supplies, each one managing either the fast rise time or the current flat top. Using solid state switches allows adapting simultaneously the pulse duration and its amplitude. This contribution presents the specific scheme and the development of a kicker system working up to 20 kV with pulse duration from 1.62 μs to 16.3 μs with transient times less than 300 ns.

THPPD072	Performance Optimization of the Stacked-Blumlein	simulation, coupling, impedance, induction	3680
	L.W. Zhang, J. Li, W.D. Wang CAEP/IFP, Mainyang, Sichuan, People's Republic of China Y. Li CAEP, Mainyang, Sichuan, People's Republic of China
	Funding: This work was supported by the National Natural Science Foundation of China (11035004) For the applications of the Dielectric Wall Accelerator (DWA), the stacked Blumlein pulse generator comprised of parallel-plate transmission lines is being developed. The peak output voltage of the stacked Blumlein will be much lower than expected due to the parasitic coupling among the individual pulse forming lines of the Blumlein stack. The finite difference time domain method is used to model the stacked Blumlein structure and determine the outputs. We present the optimization of a 20-Blumleins-stack in this paper. The results for different structures are discussed.

THPPD075	Design and Measurements of a Fast High-voltage Pulse Generator for the MedAustron Low Energy Transfer Line Fast Deflector	injection, synchrotron, power-supply, simulation	3689
	T. Fowler, M.J. Barnes, T. Kramer, F. Müller, T. Stadlbauer CERN, Geneva, Switzerland
	MedAustron, a centre for ion-therapy and research, will comprise an accelerator facility based on a synchrotron for the delivery of protons and light ions for cancer treatment. The Low Energy Beam Transfer line (LEBT) to the synchrotron contains an electrostatic fast deflector (EFE) which, when energized, deviates the continuous beam arriving from the ion source onto a Faraday Cup: the specified voltage is ±3.5 kV. De-energizing the EFE for variable pulse durations from 500 ns up to d.c. allows beam passage for multi-turn injection into the synchrotron. To maintain beam quality in the synchrotron, the EFE pulse generator requires rise and fall times of less than 300 ns between 90 % of peak voltage and a ±1 V level. To achieve this, a pulsed power supply (PKF), with high voltage MOSFET switches connected in a push-pull configuration, will be mounted in close proximity to the deflector itself. A fast, large dynamic range monitoring circuit will verify switching to the ±1 V level and subsequent flat bottom pulse quality. A prototype will be installed in the injector test stand in 2012; this paper presents the design and first measurements of the PKF and its monitoring circuit.

THPPD078	Cold Cathode Thyratron Based High-voltage Kicker Generators at the Duke Accelerators: Six Year Experience	kicker, power-supply, cathode, extraction	3698
	V. Popov, S.F. Mikhailov, P.W. Wallace, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant #DE-FG02-97ER41033. The performance of the Duke storage ring based light sources, the Duke storage ring FEL and High Intensity Gamma-ray Source (HIGS), has been greatly improved since 2007 as the result of operating a new full-energy, top-off booster injector (0.18 - 1.2 GeV), allowing fixed energy operation of the storage ring (0.25 - 1.2 GeV). The injection/extraction kicker system is one of the key components of the accelerator facility which determines efficiency and reliability of the light source operation. Pseudo-Spark Switches(PSS), also known as cold cathode thyratrons, are the critical components of the high voltage pulse generators for kickers. More than six years of operation has allowed us to study the lifetime issue for the 10 kA class devices. Recently, we have tested the next generation cold cathode thyratron, with one installed in one of our storage ring kicker high voltage generators. In the present paper we will also present preliminary test results of this new thyratron and the required modifications of its triggering driver to improve its performance.

THPPD079	Compact, High Current, High Voltage Solid State Switches for Accelerator Applications	pulsed-power, klystron, laser, linac	3701
	H.D. Sanders, S.C. Glidden APP, Freeville, USA
	Most switches used for high current, high voltage accelerator applications are vacuum or gas switches, such as spark gaps and thyratrons. Recently, high voltage IGBT based switches have become common, but are limited in current and are not compact. This paper will describe a compact, high current, high voltage solid state switch. These switches have been tested to 50kV, to greater than 12kA, to greater than 50kA/μs, to 360Hz, and to 3x10⁸ pulses, without failure. They have been used in accelerators to drive klystrons and kickers, and have been used as crowbars while offering advantages over thyratron switches for cost, lifetime, size and weight. The switches are based on series connected fast thyristors with 3cm² die in a 20cm² package. This package is more compact than TO-200 Puk sized devices, and does not require compression for proper operation. Each package is rated for 4kV, 14kA and 30kA/μs. One example, a 48kV switch which includes the trigger and snubber circuits, fits in a volume of 200mm x 85mm x 65mm, and requires only a fiber-optic trigger input. Such switches have been used on SRS and EMMA at Daresbury Laboratory in the UK, and at several US national laboratories.

THPPD081	Droop Compensation for the High Voltage Converter Modulators at the Spallation Neutron Source	controls, klystron, LLRF, cathode	3704
	G. Patel, D.E. Anderson, D.J. Solley, M. Wezensky ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725 The Spallation Neutron Source (SNS) has been in operation since 2006 and has demonstrated up to 1 MW of beam power. At 1MW, the High Voltage Converter Modulators (HVCMs) are delivering 11MW pulsed power to the Klystrons for 1185us at 60 Hz. The pulsed output of the modulator has a substantial voltage droop. The future operational goals of the accelerator involve delivering 1.4 MW to the target. This implies an increase in the output pulse width of the HVCM, resulting in loss of RF control from inadequate control margin for LLRF systems due to modulator voltage reduction at the end of pulse. Initially, the HVCM was designed with a pulse width modulation scheme for droop compensation but early operations revealed this technique unreliable for full power operation. Increasing the output voltage of the modulator would likely compromise system reliability. This paper proposes the use of alternate modulation schemes to address the voltage droop. The effect of frequency modulation and phase shift modulation on output pulse is studied and concludes by selecting an optimum modulation algorithm to be implemented. Experimental results will also be presented.

THPPD082	A Novel Solid-State Marx Modulator Topology with Voltage Droop Self-Compensation	controls, simulation, linac, factory	3707
	P. Chen, M. Lundquist, D. Yu DULY Research Inc., Rancho Palos Verdes, California, USA
	Funding: Work supported by U.S. Department of Energy SBIR grant no. DE-FG02-08ER85052. Solid-state Marx modulators are preferred over conventional modulators in accelerators and radar applications because of their high flexibility, high reliability and long life. However, voltage droop is a notable issue. A novel topology of solid-state Marx modulators is described in this paper for raising their electric energy utilization ratios (EEURs). The new Marx modulator incorporates a buck regulator circuit into each Marx cell and adopts a higher charge voltage than that of application. The topology allows Marx cells to store more electric energy and utilize the energy more efficiently than others. Initial theoretical analysis and preliminary experiments show that solid-state Marx modulators constructed with this topology and under proper control of the stepwise energy release are able to significantly enhance their EEURs. The cost effective Marx modulators with compact energy storage sizes will resolve the issue of voltage droop when they are used in high power, long pulse applications.

THPPD083	Analysis of Kicker Noise Induced Beam Emittance Growth	kicker, emittance, injection, monitoring	3710
	W. Zhang, L. A. Ahrens, I. Blackler, M. Blaskiewicz, J.M. Brennan, W. Fischer, H. Hahn, H. Huang, N.A. Kling, M. Lafky, G.J. Marr, K. Mernick, J.-L. Mi, M.G. Minty, C. Naylor, T. Roser, J. Sandberg, T.C. Shrey, B. Van Kuik, A. Zelenski 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. Over the last few years, physicists have suspected the presence of noise acting on the RHIC beams observable as occasional emittance growth at high beam energies. While the noise was sporadic in the past, it became more persistent during the run-11 setup period. An investigation diagnosed the source as originating from the RHIC abort kicker system. Once identified the issue was quickly resolved. We report in this paper the investigation result, circuit analysis, measured and simulated waveforms, solutions, and future plans.

THPPD084	Analysis of Beam Loss Induced Abort Kicker Instability	radiation, kicker, factory, electron	3713
	W. Zhang, L. A. Ahrens, W. Fischer, H. Hahn, J.-L. Mi, C. Pai, 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. Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation.

THPPD085	Research and Development of RHIC Injection Kicker Upgrade with Nano Second FID Pulse Generator	kicker, injection, monitoring, pulsed-power	3716
	W. Zhang, W. Fischer, H. Hahn, C.J. Liaw, 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. Our recent effort to test a 50 kV, 1 kA, 50 ns pulse width, 10 ns pulse rise time FID pulse generator with 250 ft transmission cable, resistive load, and existing RHIC injection kicker magnet has produced unparalleled result. This is the very first attempt to drive a high strength fast kicker magnet with a nanosecond high pulsed power (50 MVA) generator for large accelerator and colliders. The technology is impressive. We report here the result and future plan of RHIC Injection kicker upgrade.

THPPR025	Operational Efficiency of the AIRIX Accelerator Since its Commissioning	electron, site, vacuum, induction	4017
	H. Dzitko, V. Bernigaud, A. Georges, B. Gouin, G. Grandpierre, M. Mouillet CEA, Pontfaverger-Moronvilliers, France L. Buche, Y. Collet, S. Combacon, G. Gobert, R. Nicolas, R. Reynaud CEA/DAM/DIF, Arpajon, 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, the best performances and a high reliability level must be met for each experiment. This accelerator has been running for hydroshot experiments since 2000 and several thousands electron and X-ray beams have been produced so far. The functioning time of the AIRIX machine in the CEA/Moronvilliers test site is now coming to its end. From mid-2012, it will be then refurbished, dismounted and moved to another CEA test site. This paper draws up the report of AIRIX operations over this long eleven-year period. Maintenance policy, relative cost efficiency, reliability and performance results of the AIRIX accelerator over this period are dealt with and discussed.

Paper

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Other Keywords

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MOPPD006

Commissioning of the 2MeV Electron Cooler for COSY / HESR

electron, solenoid, gun, laser

379

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

The new electron cooler for COSY is built at BINP Novosibirsk. Electron beam commissioning is in progress. Installation in COSY and commissioning with proton beam is scheduled for the beginning of 2012. Beam cooling with up to 3 A of electron current at up to 2 MeV is expected to boost the luminosity in the entire energy range of COSY by counteracting the effects caused by dense targets interacting with the circulating beam. Furthermore, the 2 MeV electron cooler can be used for beam cooling at injection energy in the HESR ring in the FAIR project. The electron beam is guided by a solenoidal magnetic field all the way from the electron gun to the collector. A cascade transformer provides power to numerous high voltage sections, short solenoids, and the collector inside a pressure vessel filed with SF6 gas. Commissioning results are reported.

MOPPD045

Performance Study of the PEFP Microwave Ion Source with Modified Microwave System

ion-source, ion, proton, linac

463

D.I. Kim, Y.-S. Cho, H.S. Kim, H.-J. Kwon, K.T. Seol
KAERI, Daejon, Republic of Korea

Funding: This work is supported by the Ministry of Science and Technology of the Korean government.
A microwave ion source has been developed as a proton injector for the Proton Engineering Frontier Project (PEFP) 100-MeV proton linac. The microwave ion source consists of the 2.45-GHz microwave components, a solenoid magnet, a vacuum system, power supplies for beam extraction and bias electrode, a cooling system. It was operating for 1 year to supply beam to the 20-MeV proton accelerator. Recently, a multi-layer insulation DC break was installed between proton source and 2.45-GHz microwave components. Also, the magnetron was replaced with lower saturation power level. The tests of the microwave system have been done to study the effect of the DC break and new magnetron compared with the former one. Also, the beam test was done after the operating conditions of the microwave system were adjusted. In this paper, the performance studies of the PEFP microwave ion source with DC break and new magnetron are discussed.

MOPPD053

Reduction of Outgassing from the Ferrite Cores in the Kicker Magnet of J-PARC RCS

vacuum, kicker, beam-transport, proton

487

N. Ogiwara, Y. Hikichi, J. Kamiya, M. Kinsho, M. Nishikawa, K. Suganuma, T. Yanagibashi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Kicker magnets are used to kick out the accelerated beam to the beam transport lines in the RCS of the J-PARC. A high voltage is applied to kickers for a short period, so they must be installed in a vacuum to prevent discharge. Therefore, it is important to reduce the outgassing of water vapor from the ferrite cores. After bake-out at 200°C for 300 hours, the outgassing rate decreased to less than 1×10^-7 Pam/s. However, the small amount of water vapor and carbon monoxide were emitted from the ferrite cores at charging voltage of 80 kV. This time, we have decided to construct the reserve magnets with very low outgassing at high-voltage discharge. First of all, the thermal desorption behavior of the ferrite was investigated. Water vapor has two peaks: at ~ 100°C and 350°C. Carbon monoxide is rather largely emitted until 300°C. From these results, the ferrite cores were vacuum-fired at 450°C for 10 h. Then the good properties for the magnetic cores were confirmed. And now the assembling of the kicker magnet is undertaken. The performance of the kicker magnet made of the vacuum-fired ferrite will be shown in this meeting.

MOPPR043

Design, Construction and Calibration of a First Prototype of Beam Position System for Hadron Therapy Facilities

controls, proton, vacuum, power-supply

876

A. Faus-Golfe, C. Belver-Aguilar, C. Blanch Gutierrez, J.J. García-Garrigós
IFIC, Valencia, Spain
E. Benveniste, M. Haguenauer, P. Poilleux
LLR, Palaiseau, France

Funding: AIC10-D-000518 and AIC-D-2011-0673.
Beam Position Monitors (BPM) are essential elements in the instrumentation for the beam control in hadron therapy accelerators. The measurement of the beam position become more important at the secondary transport lines towards the patient room where this parameter must be completely determined. In this paper we describe the design, construction, read-out electronics and first calibration tests of a new type of BPM based on four scintillating fibers coupled to four photodiodes to detect the light produced by the fibers when intercepting the beam tails. The prototype will serve to evaluate the different design options in the mechanical and the read-out electronics implementation as well as to define the best processing method to get the beam position.

TUPPD050

Investigation of Laser-cleaning Process on Lead Photocathodes

laser, electron, cathode, photon

1515

S.G. Schubert, R. Barday, T. Kamps, T. Quast, A. Varykhalov
HZB, Berlin, Germany
R. Nietubyć
The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland
F. Siewert
BESSY GmbH, Berlin, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
G. Weinberg
FHI, Berlin, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin.
Metal photocathodes are widely used in electron injectors due to their stability and long life time; unfortunately they exhibit low quantum efficiency. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is further reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley*. The process was studied on witness samples in a combined photo emission, SEM and quantum efficiency measurement study. Thin Lead films were arc-deposited on optical polished Mo-substrates**. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. We followed the change of the Pb 5d signals. In the initial situation we observed signals originating from metallic Pb and Pb in the oxidized state, respectively. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM.
*J. Smedley et al, PRST-AB 11, 013502 (2008).
** Rao, T. et al., IPAC 2010, THPEC020 (2010).

TUPPD081

Development of Carbon NanoTube (CNT) Cathodes at RadiaBeam

cathode, vacuum, gun, electron

1590

L. Faillace, R.B. Agustsson, S. Boucher, A.Y. Murokh, A.V. Smirnov
RadiaBeam, Santa Monica, USA

RadiaBeam is developing Carbon Nanotube (CNT) cathodes for DC-pulsed and radio frequency (RF) driven electron sources. CNT cathodes, if realized, are capable of producing very high current density with low thermal emittance, due to ambient operating temperature. The initial experimental results of CNT cathodes are presented, including the high-voltage tests, and life time studies. CNT cathodes potential applications in accelerator science and microwave industry are discussed, and near term plans to test the CNT cathodes in the RF environment are presented.

WEPPC027

A Quarter Wave Design for Crab Crossing in the LHC

cavity, HOM, acceleration, higher-order-mode

2260

R. Calaga
CERN, Geneva, Switzerland
S.A. Belomestnykh, I. Ben-Zvi, Q. Wu
BNL, Upton, Long Island, New York, USA

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The aperture constraints of the LHC interaction region and the alternating crossing schemes at two collision points calls for a superconducting deflecting cavity with very compact dimensions at low frequencies for the purpose of crab crossing. A new concept of using a superconducting 1/4-wave design, ideally suited to address the LHC constraints at 400 MHz, is proposed. The optimized RF cavity design and associated advantages of using a 1/4 wave resonator are presented. Aspects related to higher order mode damping, multipacting and frequency tuning are also addressed.

WEPPD062

Measurements of the First RF Prototype of the Spiral2 Single Bunch Selector

vacuum, impedance, scattering, simulation

2663

M. Di Giacomo
GANIL, Caen, France
A.C. Caruso, F. Consoli, G. Gallo, D. Rifuggiato, E. Zappalà
INFN/LNS, Catania, Italy
A. Longhitano
ALTEK, San Gregorio (CATANIA), Italy

Funding: Work supported by EU commission 7th framework project n. 212692.
The single bunch selector of the Spiral2 driver uses 100 Ω travelling wave electrodes driven by fast pulse generators. A 2.5 kV, 1 kW feed-through and a vacuum chamber housing the water cooled electrodes have been designed and built. The paper reviews the whole design and reports the results of first RF and power measurements.

THAP01

Secondary-electron Emission from Hydrogen-terminated Diamond

electron, vacuum, linac, simulation

3223

E. Wang, I. Ben-Zvi, T. Rao, Q. Wu
BNL, Upton, Long Island, New York, USA
D.A. Dimitrov
Tech-X, Boulder, Colorado, USA
T. Xin
Stony Brook University, Stony Brook, USA

Diamond amplifiers demonstrably are an electron source with the potential to support high-brightness, high-average-current emission into a vacuum. We recently developed a reliable hydrogenation procedure for the diamond amplifier. The systematic study of hydrogenation resulted in the reproducible fabrication of high gain diamond amplifier. Furthermore, we measured the emission probability of diamond amplifier as a function of the external field and modeled the process with resulting changes in the vacuum level due to the Schottky effect. We demonstrated that the decrease in the secondary electrons’ average emission gain was a function of the pulse width and related this to the trapping of electrons by the effective NEA surface. The findings from the model agree well with our experimental measurements. As an application of the model, the energy spread of secondary electrons inside the diamond was estimated from the measured emission.

Slides THAP01 [2.034 MB]

THPPC016

PLSII Linac RF Conditioning Status

linac, klystron, storage-ring, vacuum

3311

H.-S. Lee, J.Y. Huang, W.H. Hwang, H.-G. Kim, K.R. Kim, S.H. Kim, S.H. Kim, S.H. Nam, W. Namkung, S.S. Park, S.J. Park, Y.J. Park, S. Shin
PAL, Pohang, Kyungbuk, Republic of Korea

PLS linac has been upgraded in energy from 2.5 to 3.0 GeV. A klystron supplies RF power of 80 MW four acceleration structures through a SLED. But our machine is not enough RF power to get 3 GeV beam energy. So we have changed the RF scheme in four modules as a klystron supplies RF power of 80 MW two accelerating structures through a SLED. There were several problems during the RF conditioning and beam operation. So we will describe the conditioning results and the current status in this paper.

THPPC048

Innovative Low-Energy Ultra-Fast Electron Diffraction (UED) System

electron, cathode, gun, vacuum

3395

L. Faillace, S. Boucher
RadiaBeam, Santa Monica, USA
P. Musumeci
UCLA, Los Angeles, California, USA

Funding: Work supported by DOE.
RadiaBeam, in collaboration with UCLA, is developing an innovative, inexpensive, low-energy ultra-fast electron diffraction (UED) system which allows us to reconstruct a single ultrafast event with a single pulse of electrons. Time resolved measurement of atomic motion is one of the frontiers of modern science, and advancements in this area will greatly improve our understanding of the basic processes in materials science, chemistry and biology. The high-frequency (GHz), high voltage, phase-locked RF field in the deflector allows temporal resolution as fine as 100 fs. In this paper, we show the complete design of a UED system based on this concept, including an optimized electron gun, a high-resolution RF deflector, and the post-interaction imaging system.

THPPC060

Commissioning of the First Klystron-based X-band Power Source at CERN

klystron, vacuum, controls, low-level-rf

3428

J.W. Kovermann, N. Catalan-Lasheras, S. Curt, S. Döbert, G. McMonagle, S.F. Rey, G. Riddone, K.M. Schirm, I. Syratchev, L. Timeo
CERN, Geneva, Switzerland
J.P. Eichner, A.A. Haase, D.W. Sprehn
SLAC, Menlo Park, California, USA
A. Hamdi, F. Peauger
CEA/DSM/IRFU, France

A new klystron based x-band rf power source working at 11.994GHz has been installed and commissioned at CERN in collaboration with CEA Saclay and SLAC for CLIC accelerating structure tests. The system comprises a solid state high voltage modulator, an XL5 klystron developed by SLAC, a cavity based SLED type pulse compressor, the necessary low level rf system including rf diagnostics and interlocks and the surrounding vacuum, cooling and controls infrastructure. The klystron can produce up to 50MW rf pulses of 1500ns pulse width and 50Hz repetition rate. After pulse compression, up to 100MW of rf power at 250ns pulse with are available in the structure test bunker. This paper describes in more detail this setup and the results of the commissioning which was necessary to arrive at the mentioned performance.

THPPC073

Development of the Energy-Efficient Solid State RF Power Source for the Jefferson Laboratory CEBAF Linac

controls, klystron, linac, insertion

3455

X. Chang, N. Barov, D.J. Newsham, D. Wu
Far-Tech, Inc., San Diego, California, USA

Funding: Work supported by DOE Office of Nuclear Physics, DOE-SBIR #DE-SC0002529
We present the current status of FAR-TECH's Solid State RF Power Source for the Jefferson Laboratory CEBAF Linac. This power source design features up to 8 kW CW RF output power, GaN amplifier stages with high efficiency (>60%), and a compact design to fit existing rack space and cooling requirements at the installation site. We have finished most of the designs and have performed successfully the most critical tests of this project, the 4 to 1 combiner test and the cooling test. FAR-TECH’s solid state amplifier design has high efficiency, a wide range of design frequency (DC-3GHz), and long lifetime, which provides a good RF power source.

THPPD053

Study on Eddy Current Power Losses in Insulated Core Transformer Primary Coil

induction, power-supply, factory, simulation

3632

L. Yang, X. Liu, Y.Q. Xiong, J. Yang
Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China
T. Yu
HUST, Wuhan, People's Republic of China

Insulated core transformer (ICT) high-voltage DC power supply is widely used in electron beam accelerator. With air gap in ICT, the reluctance of magnetic circuit is larger than other transformers, and the transverse magnetic flux leakage around the primary coil is more serious. Because the magnetic flux on the radial direction of coil cannot be ignored, the eddy current loss on the wire should be discussed. In this paper, simulation and analysis of the eddy current loss is presented. The relationship between the sizes of the coil wire is also discussed. An optimal design of the primary coil is shown.

THPPD056

Performance of the Crowbar of the LHC High Power RF System

klystron, proton, power-supply, controls

3641

G. Ravida, O. Brunner, D. Valuch
CERN, Geneva, Switzerland

During operation, the LHC high power RF equipment such as klystrons, circulators, waveguides and couplers have to be protected from damage caused by electromagnetic discharges. Once ignited, these arcs grow over the full height of the waveguide and travel towards the RF source. The burning plasma can cause serious damage to the metal surfaces or ferrite materials. The "crowbar" protection system consists of an arc current detector coupled with a fast high voltage switch in order to rapidly discharge the main high voltage components such as cables and capacitors and to shut down the high voltage source. The existing protection system, which uses a thyratron for grounding the high voltage circuit, has been installed in the LHC about 20 years ago. The problem of "faulty shots" appears due to the higher energy of LHC compared to LEP, which may lead to unnecessary stops of the LHC due to the crowbar system. This paper presents two approaches under consideration to improve the thyratron’s performance and to use a solid state thyristor in high energy environment. The main objectives will be dissipate as little energy as possible in the arc and avoid "faulty shots".

Poster THPPD056 [0.703 MB]

THPPD058

Reduction of Conductive EMI Noise Resulted from the Commercial Power Supply

power-supply, vacuum, impedance, coupling

3644

C.S. Chen, C.K. Chan, J.-C. Chang, Y.L. Chu, K.H. Hsu, C.Y. Kuo, Y.-H. Liu, C.S. Yang
NSRRC, Hsinchu, Taiwan

Almost every electronic equipment must be connected to power system. Because of the complexity of power lines, the reduction of conductive electro-magnetic interference (C-EMI) plays an important role in precise measurements. In this paper, a line impedance stabilization network (LISN) was built up to get the spectrum from power lines. After several measurements by some commercial power supplies, it is found that some of these power supplies induce effectively C-EMI into power lines, even if a passive filter is bound in power line. These noises may influence numerous equipments in a local area near the sources. Therefore, how to choose a suitable filter is a decisive factor to reduce the magnitude of C-EMI.

THPPD069

Adjustable Pulse Duration Fast Kicker for the CRYRING Storage Ring

kicker, extraction, injection, controls

3671

J.-P. Lavieville, P. Lebasque
SOLEIL, Gif-sur-Yvette, France
W. Beeckman, O. Cosson
Sigmaphi, Vannes, France

The CRYRING storage ring of the Manne Siegbahn Laboratory (MSL, Stockholm) shall be moved to become part of FLAIR accelerators complex in Darmstadt to be used for deceleration of antiprotons and charged ions. That needs an upgrade to adapt it to the full energy range (30MeV – 0.13 MeV) of its future exploitation. SIGMAPHI, in close collaboration with SOLEIL light Source, is in charge of new fast injection and extraction magnets kickers and their pulsed power supplies. The injection will be done at maximum energy (30 MeV) while the extraction need to cover the full energy range (30 MeV – 0.13 MeV) that requires a continuous adjustment capability on the pulse duration and on the deviation amplitude. The development made specifically for the CRYRING kickers is based on a new design involving two different pulsed power supplies, each one managing either the fast rise time or the current flat top. Using solid state switches allows adapting simultaneously the pulse duration and its amplitude. This contribution presents the specific scheme and the development of a kicker system working up to 20 kV with pulse duration from 1.62 μs to 16.3 μs with transient times less than 300 ns.

THPPD072

Performance Optimization of the Stacked-Blumlein

simulation, coupling, impedance, induction

3680

L.W. Zhang, J. Li, W.D. Wang
CAEP/IFP, Mainyang, Sichuan, People's Republic of China
Y. Li
CAEP, Mainyang, Sichuan, People's Republic of China

Funding: This work was supported by the National Natural Science Foundation of China (11035004)
For the applications of the Dielectric Wall Accelerator (DWA), the stacked Blumlein pulse generator comprised of parallel-plate transmission lines is being developed. The peak output voltage of the stacked Blumlein will be much lower than expected due to the parasitic coupling among the individual pulse forming lines of the Blumlein stack. The finite difference time domain method is used to model the stacked Blumlein structure and determine the outputs. We present the optimization of a 20-Blumleins-stack in this paper. The results for different structures are discussed.

THPPD075

Design and Measurements of a Fast High-voltage Pulse Generator for the MedAustron Low Energy Transfer Line Fast Deflector

injection, synchrotron, power-supply, simulation

3689

T. Fowler, M.J. Barnes, T. Kramer, F. Müller, T. Stadlbauer
CERN, Geneva, Switzerland

MedAustron, a centre for ion-therapy and research, will comprise an accelerator facility based on a synchrotron for the delivery of protons and light ions for cancer treatment. The Low Energy Beam Transfer line (LEBT) to the synchrotron contains an electrostatic fast deflector (EFE) which, when energized, deviates the continuous beam arriving from the ion source onto a Faraday Cup: the specified voltage is ±3.5 kV. De-energizing the EFE for variable pulse durations from 500 ns up to d.c. allows beam passage for multi-turn injection into the synchrotron. To maintain beam quality in the synchrotron, the EFE pulse generator requires rise and fall times of less than 300 ns between 90 % of peak voltage and a ±1 V level. To achieve this, a pulsed power supply (PKF), with high voltage MOSFET switches connected in a push-pull configuration, will be mounted in close proximity to the deflector itself. A fast, large dynamic range monitoring circuit will verify switching to the ±1 V level and subsequent flat bottom pulse quality. A prototype will be installed in the injector test stand in 2012; this paper presents the design and first measurements of the PKF and its monitoring circuit.

THPPD078

Cold Cathode Thyratron Based High-voltage Kicker Generators at the Duke Accelerators: Six Year Experience

kicker, power-supply, cathode, extraction

3698

V. Popov, S.F. Mikhailov, P.W. Wallace, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant #DE-FG02-97ER41033.
The performance of the Duke storage ring based light sources, the Duke storage ring FEL and High Intensity Gamma-ray Source (HIGS), has been greatly improved since 2007 as the result of operating a new full-energy, top-off booster injector (0.18 - 1.2 GeV), allowing fixed energy operation of the storage ring (0.25 - 1.2 GeV). The injection/extraction kicker system is one of the key components of the accelerator facility which determines efficiency and reliability of the light source operation. Pseudo-Spark Switches(PSS), also known as cold cathode thyratrons, are the critical components of the high voltage pulse generators for kickers. More than six years of operation has allowed us to study the lifetime issue for the 10 kA class devices. Recently, we have tested the next generation cold cathode thyratron, with one installed in one of our storage ring kicker high voltage generators. In the present paper we will also present preliminary test results of this new thyratron and the required modifications of its triggering driver to improve its performance.

THPPD079

Compact, High Current, High Voltage Solid State Switches for Accelerator Applications

pulsed-power, klystron, laser, linac

3701

H.D. Sanders, S.C. Glidden
APP, Freeville, USA

Most switches used for high current, high voltage accelerator applications are vacuum or gas switches, such as spark gaps and thyratrons. Recently, high voltage IGBT based switches have become common, but are limited in current and are not compact. This paper will describe a compact, high current, high voltage solid state switch. These switches have been tested to 50kV, to greater than 12kA, to greater than 50kA/μs, to 360Hz, and to 3x10⁸ pulses, without failure. They have been used in accelerators to drive klystrons and kickers, and have been used as crowbars while offering advantages over thyratron switches for cost, lifetime, size and weight. The switches are based on series connected fast thyristors with 3cm² die in a 20cm² package. This package is more compact than TO-200 Puk sized devices, and does not require compression for proper operation. Each package is rated for 4kV, 14kA and 30kA/μs. One example, a 48kV switch which includes the trigger and snubber circuits, fits in a volume of 200mm x 85mm x 65mm, and requires only a fiber-optic trigger input. Such switches have been used on SRS and EMMA at Daresbury Laboratory in the UK, and at several US national laboratories.

THPPD081

Droop Compensation for the High Voltage Converter Modulators at the Spallation Neutron Source

controls, klystron, LLRF, cathode

3704

G. Patel, D.E. Anderson, D.J. Solley, M. Wezensky
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725
The Spallation Neutron Source (SNS) has been in operation since 2006 and has demonstrated up to 1 MW of beam power. At 1MW, the High Voltage Converter Modulators (HVCMs) are delivering 11MW pulsed power to the Klystrons for 1185us at 60 Hz. The pulsed output of the modulator has a substantial voltage droop. The future operational goals of the accelerator involve delivering 1.4 MW to the target. This implies an increase in the output pulse width of the HVCM, resulting in loss of RF control from inadequate control margin for LLRF systems due to modulator voltage reduction at the end of pulse. Initially, the HVCM was designed with a pulse width modulation scheme for droop compensation but early operations revealed this technique unreliable for full power operation. Increasing the output voltage of the modulator would likely compromise system reliability. This paper proposes the use of alternate modulation schemes to address the voltage droop. The effect of frequency modulation and phase shift modulation on output pulse is studied and concludes by selecting an optimum modulation algorithm to be implemented. Experimental results will also be presented.

THPPD082

A Novel Solid-State Marx Modulator Topology with Voltage Droop Self-Compensation

controls, simulation, linac, factory

3707

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

Funding: Work supported by U.S. Department of Energy SBIR grant no. DE-FG02-08ER85052.
Solid-state Marx modulators are preferred over conventional modulators in accelerators and radar applications because of their high flexibility, high reliability and long life. However, voltage droop is a notable issue. A novel topology of solid-state Marx modulators is described in this paper for raising their electric energy utilization ratios (EEURs). The new Marx modulator incorporates a buck regulator circuit into each Marx cell and adopts a higher charge voltage than that of application. The topology allows Marx cells to store more electric energy and utilize the energy more efficiently than others. Initial theoretical analysis and preliminary experiments show that solid-state Marx modulators constructed with this topology and under proper control of the stepwise energy release are able to significantly enhance their EEURs. The cost effective Marx modulators with compact energy storage sizes will resolve the issue of voltage droop when they are used in high power, long pulse applications.

THPPD083

Analysis of Kicker Noise Induced Beam Emittance Growth

kicker, emittance, injection, monitoring

3710

W. Zhang, L. A. Ahrens, I. Blackler, M. Blaskiewicz, J.M. Brennan, W. Fischer, H. Hahn, H. Huang, N.A. Kling, M. Lafky, G.J. Marr, K. Mernick, J.-L. Mi, M.G. Minty, C. Naylor, T. Roser, J. Sandberg, T.C. Shrey, B. Van Kuik, A. Zelenski
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.
Over the last few years, physicists have suspected the presence of noise acting on the RHIC beams observable as occasional emittance growth at high beam energies. While the noise was sporadic in the past, it became more persistent during the run-11 setup period. An investigation diagnosed the source as originating from the RHIC abort kicker system. Once identified the issue was quickly resolved. We report in this paper the investigation result, circuit analysis, measured and simulated waveforms, solutions, and future plans.

THPPD084

Analysis of Beam Loss Induced Abort Kicker Instability

radiation, kicker, factory, electron

3713

W. Zhang, L. A. Ahrens, W. Fischer, H. Hahn, J.-L. Mi, C. Pai, 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.
Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation.

THPPD085

Research and Development of RHIC Injection Kicker Upgrade with Nano Second FID Pulse Generator

kicker, injection, monitoring, pulsed-power

3716

W. Zhang, W. Fischer, H. Hahn, C.J. Liaw, 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.
Our recent effort to test a 50 kV, 1 kA, 50 ns pulse width, 10 ns pulse rise time FID pulse generator with 250 ft transmission cable, resistive load, and existing RHIC injection kicker magnet has produced unparalleled result. This is the very first attempt to drive a high strength fast kicker magnet with a nanosecond high pulsed power (50 MVA) generator for large accelerator and colliders. The technology is impressive. We report here the result and future plan of RHIC Injection kicker upgrade.

THPPR025

Operational Efficiency of the AIRIX Accelerator Since its Commissioning

electron, site, vacuum, induction

4017

H. Dzitko, V. Bernigaud, A. Georges, B. Gouin, G. Grandpierre, M. Mouillet
CEA, Pontfaverger-Moronvilliers, France
L. Buche, Y. Collet, S. Combacon, G. Gobert, R. Nicolas, R. Reynaud
CEA/DAM/DIF, Arpajon, 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, the best performances and a high reliability level must be met for each experiment. This accelerator has been running for hydroshot experiments since 2000 and several thousands electron and X-ray beams have been produced so far. The functioning time of the AIRIX machine in the CEA/Moronvilliers test site is now coming to its end. From mid-2012, it will be then refurbished, dismounted and moved to another CEA test site. This paper draws up the report of AIRIX operations over this long eleven-year period. Maintenance policy, relative cost efficiency, reliability and performance results of the AIRIX accelerator over this period are dealt with and discussed.