IPAC2014 - Classification: 07 Accelerator Technology Main Systems / T16 Pulsed Power Technology

Paper	Title	Page
MOPRO028	Measurements on Prototype Inductive Adders with Ultra-flat-top Output Pulses for CLIC DR Kickers	128
	J. Holma, M.J. Barnes CERN, Geneva, Switzerland C. Belver-Aguilar IFIC, Valencia, Spain
	The CLIC study is investigating the technical feasibility of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the DR kicker systems must provide extremely flat, high-voltage, pulses. The specifications for the DR extraction kickers call for a 160 ns duration flat-top pulses of ±12.5 kV, 250 A, with a combined ripple and droop of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications because this topology allows the use of both passive and analogue modulation methods to adjust the output waveform. Recently, two five-layer, 3.5 kV, prototype inductive adders have been built at CERN. The first of these has been used to test the passive and active analogue modulation methods to compensate voltage droop and ripple of the output pulses. Pulse waveforms have been recorded with ±0.05 % relative (±1.0 V) stability for 160 ns flat-top duration at 1.823 kV.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO028
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MOPRO087	High Voltage Generators Upgrade of Siberia-2 Injection System	292
	S.I. Tomin, A. Belkov, V. Korchuganov, I. Kuzmin, K. Kuznetsov NRC, Moscow, Russia
	The injection system is one of the important systems which determine efficiency and reliability of the accelerator facility. The spark gap switches (SGS), which were used before at Siberia-2 in high voltage nanosecond pulse generators, are the critical components requiring permanent maintenance. SGS has a series of limitations such as a relatively large pulse jitter and a work at a high pressure nitrogen atmosphere. The new injection system uses new half-sine microsecond pulse generators which based on Pseudo-Spark Switches. Some technical aspects of the new injection system are considered and results of generators operation are shown in the article.
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MOPME066	Development of 400 kA Pulsed Power Supply for Magnetic Horn at FAIR Antiproton Target	517
	S.S. Mohite, R. Hettinger, K. Knie, I.J. Petzenhauser GSI, Darmstadt, Germany
	This report presents an overview of the magnetic horn and its pulsed power system at the upcoming FAIR (Facility for Antiproton and Ion Research) complex at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. In the planned antiproton (pbar) separator scheme a magnetic horn will be used as a device for collection and focusing of highly divergent antiprotons emerging from the target with energies around 3 GeV and within a cone of about 80 mrad .To achieve the desired focusing effect, the horn needs to be powered with a current pulse of 400 kA peak amplitude at the same repetition rate as the primary proton beam, i.e. 0.1 Hz. In future, operation up to 0.2 Hz is planned without major design alterations. Due to civil construction and radiation protection limitations, possible technical realization of this system has some key design issues. The aim is to develop a reliable and efficient magnetic horn system for effective focusing of antiprotons by producing a very strong pulsed magnetic field.
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MOPME067	Kicker Development at the ELBE Facility	520
	G.S. Staats FZD, Dresden, Germany A. Arnold, H. Büttig, T. Kirschke, M. Kuntzsch, P. Michel, J. Teichert, H. Vennekate, A. Wagner, R. Xiang HZDR, Dresden, Germany R. Krause-Rehberg, A. Müller Martin-Luther-Universität, Naturwissenschaftliche Fakultät II, Halle (Saale), Germany
	Kicker-devices, also known as choppers, are of great interest for a multi-purpose electron accelerator like the ELBE at HZDR. They serve the following three main tasks: Firstly, they can be used to improve the time resolution for the positron beam line by removing certain parts of the bunch. As a second advantage they enable the machine to run two independent experiments at the same, as a chopper may split the beam into two separate parts. Lastly, a well-positioned kicker can reduce the dark current emitted by the SRF injector of the accelerator. Different designs for structures, deflecting the bunch in the beam line, have been simulated using CST Particle Studio. Here, no big difference to well-known strip line structures do exist. The next step is to design the supply electronics driving the kickers. As the ELBE accelerator runs at a high bunch repetition rate, the kicker has to keep up to this frequencies of up to 13 MHz. Hence, the high power levels needed for the operation may cause additional problems for the driver electronics. The poster is going to present the state of our development for all three tasks and our approaches to solve the corresponding challenges.
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MOPME068	SiC-JFET Switching Power Supply toward for Induction Ring Accelerators	523
	K. Okamura, K. Takayama, M. Wake, T. Yoshimoto KEK, Ibaraki, Japan R. Sasaki, K. Takaki Iwate university, Morioka, Iwate, Japan K. Takayama, T. Yoshimoto TIT, Yokohama, Japan F. Tamura Nagaoka University of Technology, Nagaoka, Niigata, Japan
	Funding: Japan Science and Technology Agency Grant-In Aid for Scientific Research(s) (KAKENHI No. 24310077) A new induction synchrotron system using an induction cell has been developed and constructed at KEK. In that system, the switching power supply is one of the key devices that realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device. However, series connection gives large complexity and less reliability. Among various switching devices, a SiC-JFET should be a promising candidate because it has ultrafast switching speed and high voltage blocking capability. We have developed a new and original SiC-JFET switching device and a compact switching power supply employing this switching element. Now it is integrated into the induction acceleration system for the KEK-DA. Furthermore we have started development of the next generation of SiC package, which has higher voltage capability (2.4 kV) and 2 in 1 module construction. At the conference, the first experimental demonstration of heavy ion acceleration utilizing the SiC-JFET and the design status of the new device package will be presented. T. Iwashita et al., Phys. Rev. ST-AB 14, 071302 (2011). ** K. Okamura et al., “A Compact Switching Power Supply Utilizing SiC-JFET for The Digital Accelerator ”, in Proc. of IPAC’12, pp 3677-3679.
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MOPME069	Upgrade of the Injection Kicker System for J-PARC Main Ring	526
	T. Sugimoto, K. Fan, K. Ishii, H. Matsumoto KEK, Ibaraki, Japan
	Four lumped inductance injection kicker magnets for the J-PARC main ring (MR) produce a kick of 0.1096 T·m with a 1% to 99% rise-time of about 400 nsec. A residual field of about 6% of the flat-top exists at the tail of the pulse due to an impedance mismatching. The residual field is required to be suppressed less than 1% to reduce injection losses. For a higher intensity beam operation, the kicker rise-time of less than 300nsec is required to inject longer beam bunches which reduces a space charge effect. During the long shutdown in FY2013, 140Ω resistor and 7nF capacitor were connected to the thyratron to improve the post-pulse shape. In addition, an optimization of a capacitance in the matching circuit was carried out to optimize the waveform. As the result, the rise-time of 195nsec and the residual tail field of 2% were achieved. However, another reflection peak of about 9% is appeared. We plan to compensate the effect of the new peak by using a new small kicker magnet. This paper discusses the detail of the circuit and the beam test results.
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MOPME070	Investigation of a High Power, Low Impedance Pulse Forming Network based on Ceramic Capacitors	529
	J. Gao, X.J. Ge, J. He, J. Liu NUDT, Changsha, People's Republic of China
	Solid state is one of the most important development directions for pulsed power technologies. For GW level pulse generators, switches and pulse forming units are difficult to implement with solid state components restricted by high power tolerance and high voltage insulation. Under certain pulse power, operation voltage is decided by impedance of the pulse forming unit, which means that pulse modulation with low impedance method should help improve insulation strength of a pulsed power system. Therefore, a high power, low impedance pulse forming network is developed based on solid components of ceramic capacitors in this research. It is designed that the impedance is 1.6 Ω, the pulse width is about 150 ns, and the output power is above 1 GW. Low impedance is accomplished via several pulse forming units connected in parallel with a circumferential structure, which could reduce the stray inductance due to good symmetrical characteristics. Key factors influencing pulse modulation process are investigated, stray parameters are examined by electromagnetic calculations and preliminary experiments are carried out, with results giving reasonable agreement with the theoretical cases.
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MOPME071	Configurations and Applications of Saturable Pulse Transformers in High Power Pulse Modulation	532
	J. Liu, J. Gao, X.J. Ge, J. He, Y. Zhang NUDT, Changsha, People's Republic of China
	Saturable pulse transformers (SPTs) based on multiple batches of windings in parallel combination and coaxial cylindrical conductors are presented. The proposed SPT can be employed as the transformer and magnetic switch simultaneously for pulse capacitor or high-voltage pulse modulator of several hundred kV range. The SPT, with important features such as auto-resetting of core, high step-up ratio and low saturation inductance, achieves a compact integration of common transformer and magnetic switch. In the SPT, The physical suppression effect caused by reversed magnetic coupling mechanism among primary and secondary windings can reduce the saturation inductance of the SPT windings to a level lower than their structure inductances, which helps to achieve a magnetic switch with low saturation inductance. The proposed SPTs were applied in a high power pulse modulator based on a helical Blumlein pulse forming line (HBPFL). When the SPT played as a pulse transformer, the HBPFL can be charged to 200 kV. When the SPT played as a main magnetic switch of the HBPFL, it helped to form a quasi-square voltage pulse with amplitude of 180 kV，pulse duration of 130 ns, rise time of 60 ns.
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MOPME072	Pulse Power Supplies for the Dipole Kickers of MAX-IV and Solaris Storage Rings	535
	A.A. Korepanov, A.A. Eliseev, A. Panov, A.A. Starostenko BINP SB RAS, Novosibirsk, Russia
	For initial operation of the MAX-IV and Solaris storage rings the single dipole kickers were decided to use. The pulsers wich drive the magnets have the following requirements: current amplitude up to 4kA (3 GeV ring), pulse length 0.6us (1.5 GeV ring) and 3.5us (3 GeV ring), pulse amplitude stability ±0.1%, timing jitter <±5ns, maximium repetition frequency 10 Hz. The design and test results of the pulse power supplies are presented in the paper.
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MOPME074	High Voltage Performance of the Beam Screen of the LHC Injection Kicker Magnets	541
	M.J. Barnes, P. Adraktas, G. Bregliozzi, S. Calatroni, P. Costa Pinto, H.A. Day, L. Ducimetière, V. Gomes Namora, T. Kramer, V. Mertens, M. Taborelli CERN, Geneva, Switzerland
	The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wakefields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. The design of the beam screen has been upgraded to overcome limitations and permit LHC operation with increasingly higher bunch intensity and short bunch lengths: the new design also significantly reduces the electric field associated with the screen conductors, decreasing the probability of electrical breakdown. The high voltage conditioning process for the upgraded kicker magnets is presented and discussed. In addition a test setup has been utilized to study flashover, on the inner wall of the ceramic tube, as a function of both applied voltage and vacuum pressure: results from the test setup are presented.
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MOPME075	Cooling of the LHC Injection Kicker Magnet Ferrite Yoke: Measurements and Future Proposals	544
	M.J. Barnes, S. Bouleghlimat, L. Ducimetière, M. Garlaschè, V. Gomes Namora, T. Kramer, R. Noulibos, Y. Sillanoli, Z.K. Sobiech, W.J.M. Weterings CERN, Geneva, Switzerland
	LHC operation with high intensity beam, stable for many hours, resulted in significant heating of the ferrite yoke of the LHC Injection Kicker Magnets. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the yoke can require several hours to cool sufficiently to allow re-injection of beam, thus limiting the running efficiency of the LHC. The beam screen, which screens the ferrite yoke from wakefields, has been upgraded to limit ferrite heating. In addition it is important to improve the cooling of the ferrite yoke: one method is to increase the internal emissivity of the cylindrical vacuum tank, in which the kicker magnet is installed. This paper describes a method developed for measuring the emissivity of the inside of the tanks, which has been benchmarked against measurements of the ferrite yoke temperature during heat treatment in an oven and transient thermal simulations. Conclusions are drawn regarding an ion bombardment technique evaluated for improving emissivity without degrading vacuum properties. In addition initial concepts for improved cooling are presented.
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MOPME078	Relief of an Electric Field via a Cone Structure	550
	Y.T. Huang, C.K. Chan, C.S. Chen, J.-R. Chen, G.-Y. Hsiung, Y.-H. Liu NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	A terminated power cable is typically applied not only for terminated ends but also to connect two or more cables. The electric field inside the insulation layer becomes disturbed when a coaxial cable structure is broken and the electric stress increases near the ground edge. A structure of cone type is a major method to alter the lines of equi- potential and to relieve the electric stress around the ground. The dimensions of the cone depend on the cable structure. In this paper we introduce a way to calculate the displacement of equi-potential lines when a cone is brought into a coaxial cable, RG220, and then determine a suitable angle and length of the cone, which are important factors to withstand tens of kV and even greater. The corresponding high-voltage tests are also presented here.
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MOPME079	The DC and AC Withstands Test for TPS Booster Injection Kicker	554
	Y.-H. Liu, C.K. Chan, C.-S. Chen, H.H. Chen, J.-R. Chen, Y.T. Huang, C.S. Yang NSRRC, Hsinchu, Taiwan
	TPS requires highly precise and stable pulsed magnets for top-up mode operation. One injection and two extraction in vacuum kicker magnets in the booster ring are designed and noticed to minimize driving voltage. The HV insulation for magnet itself and vacuum feedthrough need to be tested. A DC withstand voltage tester MUSASHI 3802 (Model: IP-701G) is used to test the DC breakdown voltage, which the maximum driving voltage is 37 kV. And the AC withstand voltage tester was also test the AC breakdown voltage. Thicker than 10 mm ceramic plate could effectively avoid the breakdown occurred with 37 kV DC charging. Thus HV withstand voltage will be higher in vacuum chamber and the insulation with HV will not be the problem.
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MOPME080	Affordable Short Pulse Marx Modulator	557
	R.A. Phillips, G. DelPriore, M.P.J. Gaudreau, M.K. Kempkes Diversified Technologies, Inc., Bedford, Massachusetts, USA J.A. Casey Rockfield Research Inc., Las Vegas, Nevada, USA
	Funding: US Department of Energy, Award DE-SC00004251 High energy, short-pulse modulators are being re-examined for the Compact Linear Collider (CLIC) and numerous X-Band accelerator designs. At the very high voltages required for these systems, all of the existing designs are based on pulse transformers, which significantly limit their performance and efficiency. There is not a fully optimized, transformerless modulator design capable of meeting the demanding requirements of very high voltage pulses at short pulse widths. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) 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 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort are modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies. The system is in the final stages of testing prior to installation at Yale University.
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MOPME081	A Stripline Kicker Driver for the Next Generation Light Source	559
	F.M. Niell, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, J. Kinross-Wright Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: US Department of Energy, Award DE-SC00004255 Diversified Technologies, Inc. (DTI) assembled a prototype pulse generator capable of meeting the original specifications for the Next Generation Light Source (NGLS) fast deflector. The ultimate NGLS kicker driver must drive a 50 Ω terminated Transverse Electromagnetic (TEM) deflector blade at 10 kV, with flat-topped pulses and a sustained repetition rate of 100 kHz. Additional requirements of the specification include a 2 ns rise time (10 – 90%), a highly repeatable flattop with pulse width from 5 – 40 ns, and a fall time less than 1 μs (down to 10-4 of the peak value). The driver must also effectively absorb high-order mode signals emerging from the deflector itself. It is envisioned that a scintilla of deflection will be imparted by a symmetric pair of shaped parallel deflection blades, pulsed in opposition at 10 kV. Within the guide, each TEM wave produced by the two pulse generators traverses the guide synchronously with the selected (relativistic) charge packet. The DTI team has designed and demonstrated the key elements of a solid state kicker driver capable of meeting the NGLS requirements, with possible extension to a wide range of fast-pulse applications.
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MOPME082	ILC-Class Marx Modulator at KEK	562
	M.P.J. Gaudreau, N. Silverman, B.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA J.A. Casey Rockfield Research Inc., Las Vegas, Nevada, USA
	Funding: US Department of Energy, Award DE-FG02-05ER84352 KEK, High Energy Accelerator Research Organization In October 2013, Diversified Technologies, Inc. (DTI) successfully installed and began operation of a 120 kV, 120 A, 1.7 ms Marx modulator for the High Energy Accelerator Research Organization (KEK) in Japan. Originally conceived, and built under a DOE SBIR grant to support SLAC (completed in 2010), the Marx bank modulator demonstrates a new technology for compact and economic ILC-class performance; the design meets the performance requirements for ILC, does so in a more compact form factor than other known technologies, and, we believe, will be more economic than other technologies. The basic concept of a Marx modulator is that it charges an array of capacitors in parallel (low voltage), then erects them in series to form a high-voltage discharge. Using DTI’s solid-state switches (instead of traditional spark gaps or SCRs) to construct a Marx modulator enables it to open and close; thus the capacitors serve as storage capacitors rather than fully exhausting during each pulse. The opening capability of the DTI switches also provides for arc protection of the load, exactly as they would in a hard-switch. Such a system requires no crowbar protection to protect the load against arcs.
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MOPME083	Fast Kicker Systems for ALS-U	564
	G.C. Pappas, S. De Santis, J.E. Galvin, L.R. Reginato, C. Steier, C. Sun, H. Tarawneh, W.L. Waldron LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 Fast kicker systems are required for the proposed upgrade of ALS to a diffraction-limited light source (ALS-U). The main approach is to have multiple stripline kicker magnets driven by inductive adders. The design details of the kicker structures and the inductive adder options will be discussed.
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Paper

Title

Page

Measurements on Prototype Inductive Adders with Ultra-flat-top Output Pulses for CLIC DR Kickers

128

J. Holma, M.J. Barnes
CERN, Geneva, Switzerland
C. Belver-Aguilar
IFIC, Valencia, Spain

The CLIC study is investigating the technical feasibility of an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. To avoid beam emittance increase, the DR kicker systems must provide extremely flat, high-voltage, pulses. The specifications for the DR extraction kickers call for a 160 ns duration flat-top pulses of ±12.5 kV, 250 A, with a combined ripple and droop of not more than ±0.02 % (±2.5 V). An inductive adder is a very promising approach to meeting the specifications because this topology allows the use of both passive and analogue modulation methods to adjust the output waveform. Recently, two five-layer, 3.5 kV, prototype inductive adders have been built at CERN. The first of these has been used to test the passive and active analogue modulation methods to compensate voltage droop and ripple of the output pulses. Pulse waveforms have been recorded with ±0.05 % relative (±1.0 V) stability for 160 ns flat-top duration at 1.823 kV.

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MOPRO087

High Voltage Generators Upgrade of Siberia-2 Injection System

292

S.I. Tomin, A. Belkov, V. Korchuganov, I. Kuzmin, K. Kuznetsov
NRC, Moscow, Russia

The injection system is one of the important systems which determine efficiency and reliability of the accelerator facility. The spark gap switches (SGS), which were used before at Siberia-2 in high voltage nanosecond pulse generators, are the critical components requiring permanent maintenance. SGS has a series of limitations such as a relatively large pulse jitter and a work at a high pressure nitrogen atmosphere. The new injection system uses new half-sine microsecond pulse generators which based on Pseudo-Spark Switches. Some technical aspects of the new injection system are considered and results of generators operation are shown in the article.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO087

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MOPME066

Development of 400 kA Pulsed Power Supply for Magnetic Horn at FAIR Antiproton Target

517

S.S. Mohite, R. Hettinger, K. Knie, I.J. Petzenhauser
GSI, Darmstadt, Germany

This report presents an overview of the magnetic horn and its pulsed power system at the upcoming FAIR (Facility for Antiproton and Ion Research) complex at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. In the planned antiproton (pbar) separator scheme a magnetic horn will be used as a device for collection and focusing of highly divergent antiprotons emerging from the target with energies around 3 GeV and within a cone of about 80 mrad .To achieve the desired focusing effect, the horn needs to be powered with a current pulse of 400 kA peak amplitude at the same repetition rate as the primary proton beam, i.e. 0.1 Hz. In future, operation up to 0.2 Hz is planned without major design alterations. Due to civil construction and radiation protection limitations, possible technical realization of this system has some key design issues. The aim is to develop a reliable and efficient magnetic horn system for effective focusing of antiprotons by producing a very strong pulsed magnetic field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME066

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MOPME067

Kicker Development at the ELBE Facility

520

G.S. Staats
FZD, Dresden, Germany
A. Arnold, H. Büttig, T. Kirschke, M. Kuntzsch, P. Michel, J. Teichert, H. Vennekate, A. Wagner, R. Xiang
HZDR, Dresden, Germany
R. Krause-Rehberg, A. Müller
Martin-Luther-Universität, Naturwissenschaftliche Fakultät II, Halle (Saale), Germany

Kicker-devices, also known as choppers, are of great interest for a multi-purpose electron accelerator like the ELBE at HZDR. They serve the following three main tasks: Firstly, they can be used to improve the time resolution for the positron beam line by removing certain parts of the bunch. As a second advantage they enable the machine to run two independent experiments at the same, as a chopper may split the beam into two separate parts. Lastly, a well-positioned kicker can reduce the dark current emitted by the SRF injector of the accelerator. Different designs for structures, deflecting the bunch in the beam line, have been simulated using CST Particle Studio. Here, no big difference to well-known strip line structures do exist. The next step is to design the supply electronics driving the kickers. As the ELBE accelerator runs at a high bunch repetition rate, the kicker has to keep up to this frequencies of up to 13 MHz. Hence, the high power levels needed for the operation may cause additional problems for the driver electronics. The poster is going to present the state of our development for all three tasks and our approaches to solve the corresponding challenges.

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MOPME068

SiC-JFET Switching Power Supply toward for Induction Ring Accelerators

523

K. Okamura, K. Takayama, M. Wake, T. Yoshimoto
KEK, Ibaraki, Japan
R. Sasaki, K. Takaki
Iwate university, Morioka, Iwate, Japan
K. Takayama, T. Yoshimoto
TIT, Yokohama, Japan
F. Tamura
Nagaoka University of Technology, Nagaoka, Niigata, Japan

Funding: Japan Science and Technology Agency Grant-In Aid for Scientific Research(s) (KAKENHI No. 24310077)
A new induction synchrotron system using an induction cell has been developed and constructed at KEK*. In that system, the switching power supply is one of the key devices that realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device. However, series connection gives large complexity and less reliability. Among various switching devices, a SiC-JFET should be a promising candidate because it has ultrafast switching speed and high voltage blocking capability. We have developed a new and original SiC-JFET switching device and a compact switching power supply employing this switching element**. Now it is integrated into the induction acceleration system for the KEK-DA. Furthermore we have started development of the next generation of SiC package, which has higher voltage capability (2.4 kV) and 2 in 1 module construction. At the conference, the first experimental demonstration of heavy ion acceleration utilizing the SiC-JFET and the design status of the new device package will be presented.
* T. Iwashita et al., Phys. Rev. ST-AB 14, 071302 (2011).
** K. Okamura et al., “A Compact Switching Power Supply Utilizing SiC-JFET for The Digital Accelerator ”, in Proc. of IPAC’12, pp 3677-3679.

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MOPME069

Upgrade of the Injection Kicker System for J-PARC Main Ring

526

T. Sugimoto, K. Fan, K. Ishii, H. Matsumoto
KEK, Ibaraki, Japan

Four lumped inductance injection kicker magnets for the J-PARC main ring (MR) produce a kick of 0.1096 T·m with a 1% to 99% rise-time of about 400 nsec. A residual field of about 6% of the flat-top exists at the tail of the pulse due to an impedance mismatching. The residual field is required to be suppressed less than 1% to reduce injection losses. For a higher intensity beam operation, the kicker rise-time of less than 300nsec is required to inject longer beam bunches which reduces a space charge effect. During the long shutdown in FY2013, 140Ω resistor and 7nF capacitor were connected to the thyratron to improve the post-pulse shape. In addition, an optimization of a capacitance in the matching circuit was carried out to optimize the waveform. As the result, the rise-time of 195nsec and the residual tail field of 2% were achieved. However, another reflection peak of about 9% is appeared. We plan to compensate the effect of the new peak by using a new small kicker magnet. This paper discusses the detail of the circuit and the beam test results.

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MOPME070

Investigation of a High Power, Low Impedance Pulse Forming Network based on Ceramic Capacitors

529

J. Gao, X.J. Ge, J. He, J. Liu
NUDT, Changsha, People's Republic of China

Solid state is one of the most important development directions for pulsed power technologies. For GW level pulse generators, switches and pulse forming units are difficult to implement with solid state components restricted by high power tolerance and high voltage insulation. Under certain pulse power, operation voltage is decided by impedance of the pulse forming unit, which means that pulse modulation with low impedance method should help improve insulation strength of a pulsed power system. Therefore, a high power, low impedance pulse forming network is developed based on solid components of ceramic capacitors in this research. It is designed that the impedance is 1.6 Ω, the pulse width is about 150 ns, and the output power is above 1 GW. Low impedance is accomplished via several pulse forming units connected in parallel with a circumferential structure, which could reduce the stray inductance due to good symmetrical characteristics. Key factors influencing pulse modulation process are investigated, stray parameters are examined by electromagnetic calculations and preliminary experiments are carried out, with results giving reasonable agreement with the theoretical cases.

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MOPME071

Configurations and Applications of Saturable Pulse Transformers in High Power Pulse Modulation

532

J. Liu, J. Gao, X.J. Ge, J. He, Y. Zhang
NUDT, Changsha, People's Republic of China

Saturable pulse transformers (SPTs) based on multiple batches of windings in parallel combination and coaxial cylindrical conductors are presented. The proposed SPT can be employed as the transformer and magnetic switch simultaneously for pulse capacitor or high-voltage pulse modulator of several hundred kV range. The SPT, with important features such as auto-resetting of core, high step-up ratio and low saturation inductance, achieves a compact integration of common transformer and magnetic switch. In the SPT, The physical suppression effect caused by reversed magnetic coupling mechanism among primary and secondary windings can reduce the saturation inductance of the SPT windings to a level lower than their structure inductances, which helps to achieve a magnetic switch with low saturation inductance. The proposed SPTs were applied in a high power pulse modulator based on a helical Blumlein pulse forming line (HBPFL). When the SPT played as a pulse transformer, the HBPFL can be charged to 200 kV. When the SPT played as a main magnetic switch of the HBPFL, it helped to form a quasi-square voltage pulse with amplitude of 180 kV，pulse duration of 130 ns, rise time of 60 ns.

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MOPME072

Pulse Power Supplies for the Dipole Kickers of MAX-IV and Solaris Storage Rings

535

A.A. Korepanov, A.A. Eliseev, A. Panov, A.A. Starostenko
BINP SB RAS, Novosibirsk, Russia

For initial operation of the MAX-IV and Solaris storage rings the single dipole kickers were decided to use. The pulsers wich drive the magnets have the following requirements: current amplitude up to 4kA (3 GeV ring), pulse length 0.6us (1.5 GeV ring) and 3.5us (3 GeV ring), pulse amplitude stability ±0.1%, timing jitter <±5ns, maximium repetition frequency 10 Hz. The design and test results of the pulse power supplies are presented in the paper.

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MOPME074

High Voltage Performance of the Beam Screen of the LHC Injection Kicker Magnets

541

M.J. Barnes, P. Adraktas, G. Bregliozzi, S. Calatroni, P. Costa Pinto, H.A. Day, L. Ducimetière, V. Gomes Namora, T. Kramer, V. Mertens, M. Taborelli
CERN, Geneva, Switzerland

The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wakefields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. The design of the beam screen has been upgraded to overcome limitations and permit LHC operation with increasingly higher bunch intensity and short bunch lengths: the new design also significantly reduces the electric field associated with the screen conductors, decreasing the probability of electrical breakdown. The high voltage conditioning process for the upgraded kicker magnets is presented and discussed. In addition a test setup has been utilized to study flashover, on the inner wall of the ceramic tube, as a function of both applied voltage and vacuum pressure: results from the test setup are presented.

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MOPME075

Cooling of the LHC Injection Kicker Magnet Ferrite Yoke: Measurements and Future Proposals

544

M.J. Barnes, S. Bouleghlimat, L. Ducimetière, M. Garlaschè, V. Gomes Namora, T. Kramer, R. Noulibos, Y. Sillanoli, Z.K. Sobiech, W.J.M. Weterings
CERN, Geneva, Switzerland

LHC operation with high intensity beam, stable for many hours, resulted in significant heating of the ferrite yoke of the LHC Injection Kicker Magnets. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the yoke can require several hours to cool sufficiently to allow re-injection of beam, thus limiting the running efficiency of the LHC. The beam screen, which screens the ferrite yoke from wakefields, has been upgraded to limit ferrite heating. In addition it is important to improve the cooling of the ferrite yoke: one method is to increase the internal emissivity of the cylindrical vacuum tank, in which the kicker magnet is installed. This paper describes a method developed for measuring the emissivity of the inside of the tanks, which has been benchmarked against measurements of the ferrite yoke temperature during heat treatment in an oven and transient thermal simulations. Conclusions are drawn regarding an ion bombardment technique evaluated for improving emissivity without degrading vacuum properties. In addition initial concepts for improved cooling are presented.

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MOPME078

Relief of an Electric Field via a Cone Structure

550

Y.T. Huang, C.K. Chan, C.S. Chen, J.-R. Chen, G.-Y. Hsiung, Y.-H. Liu
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

A terminated power cable is typically applied not only for terminated ends but also to connect two or more cables. The electric field inside the insulation layer becomes disturbed when a coaxial cable structure is broken and the electric stress increases near the ground edge. A structure of cone type is a major method to alter the lines of equi- potential and to relieve the electric stress around the ground. The dimensions of the cone depend on the cable structure. In this paper we introduce a way to calculate the displacement of equi-potential lines when a cone is brought into a coaxial cable, RG220, and then determine a suitable angle and length of the cone, which are important factors to withstand tens of kV and even greater. The corresponding high-voltage tests are also presented here.

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MOPME079

The DC and AC Withstands Test for TPS Booster Injection Kicker

554

Y.-H. Liu, C.K. Chan, C.-S. Chen, H.H. Chen, J.-R. Chen, Y.T. Huang, C.S. Yang
NSRRC, Hsinchu, Taiwan

TPS requires highly precise and stable pulsed magnets for top-up mode operation. One injection and two extraction in vacuum kicker magnets in the booster ring are designed and noticed to minimize driving voltage. The HV insulation for magnet itself and vacuum feedthrough need to be tested. A DC withstand voltage tester MUSASHI 3802 (Model: IP-701G) is used to test the DC breakdown voltage, which the maximum driving voltage is 37 kV. And the AC withstand voltage tester was also test the AC breakdown voltage. Thicker than 10 mm ceramic plate could effectively avoid the breakdown occurred with 37 kV DC charging. Thus HV withstand voltage will be higher in vacuum chamber and the insulation with HV will not be the problem.

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MOPME080

Affordable Short Pulse Marx Modulator

557

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

Funding: US Department of Energy, Award DE-SC00004251
High energy, short-pulse modulators are being re-examined for the Compact Linear Collider (CLIC) and numerous X-Band accelerator designs. At the very high voltages required for these systems, all of the existing designs are based on pulse transformers, which significantly limit their performance and efficiency. There is not a fully optimized, transformerless modulator design capable of meeting the demanding requirements of very high voltage pulses at short pulse widths. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) 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 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort are modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies. The system is in the final stages of testing prior to installation at Yale University.

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MOPME081

A Stripline Kicker Driver for the Next Generation Light Source

559

F.M. Niell, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, J. Kinross-Wright
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: US Department of Energy, Award DE-SC00004255
Diversified Technologies, Inc. (DTI) assembled a prototype pulse generator capable of meeting the original specifications for the Next Generation Light Source (NGLS) fast deflector. The ultimate NGLS kicker driver must drive a 50 Ω terminated Transverse Electromagnetic (TEM) deflector blade at 10 kV, with flat-topped pulses and a sustained repetition rate of 100 kHz. Additional requirements of the specification include a 2 ns rise time (10 – 90%), a highly repeatable flattop with pulse width from 5 – 40 ns, and a fall time less than 1 μs (down to 10-4 of the peak value). The driver must also effectively absorb high-order mode signals emerging from the deflector itself. It is envisioned that a scintilla of deflection will be imparted by a symmetric pair of shaped parallel deflection blades, pulsed in opposition at 10 kV. Within the guide, each TEM wave produced by the two pulse generators traverses the guide synchronously with the selected (relativistic) charge packet. The DTI team has designed and demonstrated the key elements of a solid state kicker driver capable of meeting the NGLS requirements, with possible extension to a wide range of fast-pulse applications.

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MOPME082

ILC-Class Marx Modulator at KEK

562

M.P.J. Gaudreau, N. Silverman, B.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA
J.A. Casey
Rockfield Research Inc., Las Vegas, Nevada, USA

Funding: US Department of Energy, Award DE-FG02-05ER84352 KEK, High Energy Accelerator Research Organization
In October 2013, Diversified Technologies, Inc. (DTI) successfully installed and began operation of a 120 kV, 120 A, 1.7 ms Marx modulator for the High Energy Accelerator Research Organization (KEK) in Japan. Originally conceived, and built under a DOE SBIR grant to support SLAC (completed in 2010), the Marx bank modulator demonstrates a new technology for compact and economic ILC-class performance; the design meets the performance requirements for ILC, does so in a more compact form factor than other known technologies, and, we believe, will be more economic than other technologies. The basic concept of a Marx modulator is that it charges an array of capacitors in parallel (low voltage), then erects them in series to form a high-voltage discharge. Using DTI’s solid-state switches (instead of traditional spark gaps or SCRs) to construct a Marx modulator enables it to open and close; thus the capacitors serve as storage capacitors rather than fully exhausting during each pulse. The opening capability of the DTI switches also provides for arc protection of the load, exactly as they would in a hard-switch. Such a system requires no crowbar protection to protect the load against arcs.

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MOPME083

Fast Kicker Systems for ALS-U

564

G.C. Pappas, S. De Santis, J.E. Galvin, L.R. Reginato, C. Steier, C. Sun, H. Tarawneh, W.L. Waldron
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
Fast kicker systems are required for the proposed upgrade of ALS to a diffraction-limited light source (ALS-U). The main approach is to have multiple stripline kicker magnets driven by inductive adders. The design details of the kicker structures and the inductive adder options will be discussed.

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