IPAC2014 - List of Keywords (high-voltage)

Paper	Title	Other Keywords	Page
MOPRO020	FLUKA Simulation of Particle Fluences to ALICE due to LHC Injection Kicker Failures	injection, simulation, kicker, detector	109
	N.V. Shetty, C. Bracco, A. Di Mauro, A. Lechner, E. Leogrande, J.A. Uythoven CERN, Geneva, Switzerland
	The counter-rotating beams of the LHC are injected in insertion regions which also accommodate the ALICE and LHCb experiments. An assembly of beam absorbers ensures the protection of machine elements in case of injection kicker failures, which can affect either the injected or the stored beam. In the first years of LHC operation, secondary particle showers due to beam impact on the injection beam stopper caused damage to the MOS injectors of the ALICE silicon drift detector as well as high-voltage trips in other ALICE subdetectors. In this study, we present FLUKA simulations of particle fluences to the ALICE cavern for injection failures encountered during operation. Two different cases are reported, one where the miskicked beam is fully intercepted and one where the beam grazes the beam stopper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO020
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MOPRO028	Measurements on Prototype Inductive Adders with Ultra-flat-top Output Pulses for CLIC DR Kickers	kicker, flattop, damping, operation	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	kicker, injection, operation, power-supply	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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MOPME051	Turbo Generators for Powering the HV-solenoids at the HESR Electron Cooler	solenoid, electron, power-supply, acceleration	492
	A. Hofmann, K. Aulenbacher, M.W. Bruker, J. Dietrich, T. Weilbach HIM, Mainz, Germany M.I. Bryzgunov, A.P. Denisov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva BINP SB RAS, Novosibirsk, Russia
	New experiments at the planned 'High Energy Storage Ring' (HESR) require magnetised electron cooling. One of the challenges is the powering of the HV-solenoids, because they are located on HV-sections, which sit on an electrical potential inside a high voltage vessel. We discuss a Multi-MV system where the solenoids are powered by a series of cascade transformers which are in turn supplied by turbogenerators. The usage of SF6 as turbine fluid is desirable from the viewpoint of operational stability and may also lead to energy efficient operation of the turboexpanders since a Organic Rankine-cycle (so-called ORC-process) may be used instead of electrically driven compressors. The paper gives an overview of the turbo generator and ORC project: an introduction, a status report and a road map will be given.
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MOPME071	Configurations and Applications of Saturable Pulse Transformers in High Power Pulse Modulation	coupling, experiment, plasma, controls	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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MOPME078	Relief of an Electric Field via a Cone Structure	kicker, extraction, booster, vacuum	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME078
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MOPME080	Affordable Short Pulse Marx Modulator	controls, network, flattop, linear-collider	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME080
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MOPME081	A Stripline Kicker Driver for the Next Generation Light Source	kicker, simulation, coupling, impedance	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME081
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MOPME082	ILC-Class Marx Modulator at KEK	controls, damping, operation, flattop	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME082
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MOPRI074	Conceptual Project Relativistic Electron Cooler for FAIR/HESR	electron, proton, acceleration, cathode	774
	V.V. Parkhomchuk, M.I. Bryzgunov, A.P. Denisov, V.M. Panasiuk, V.B. Reva BINP SB RAS, Novosibirsk, Russia K. Aulenbacher, J. Dietrich HIM, Mainz, Germany V. Kamerdzhiev FZJ, Jülich, Germany
	To develop a 4 MeV relativistic electron cooling system for the HESR storage ring, which is part of the future GSI facility FAIR, is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the upgrade to 8 MeV of the relativistic electron cooler is essential for the future Electron Nucleon Collider (ENC@FAIR) project. The basic feature of the design are the power for magnet field coils at accelerating and decelerating column is generated by turbines (one option under investigation in this research group) operated on SF6 gas under pressure
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI074
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TUPME039	System Integration of the Demonstration Siemens Electrostatic Accelerator	ion-source, ion, power-supply, experiment	1440
	H. von Jagwitz-Biegnitz JAI, Oxford, United Kingdom P. Beasley, S. Goßmann-Levchuk, O. Heid Siemens AG, Erlangen, Germany D.C. Faircloth STFC/RAL, Chilton, Didcot, Oxon, United Kingdom R.G. Selway Inspired Engineering Ltd, Climping, United Kingdom
	Siemens has proposed a novel compact DC electrostatic tandem accelerator to produce protons of a few MeV. Siemens is currently building a prototype of the accelerator at the Rutherford Appleton Laboratory. This paper reports on recent progress on the different components of the system as well as the commissioning of the whole machine.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME039
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WEPME004	Prediction of Severe Electron Loading of High-gradient Accelerating Structures based on Field Emission Measurements of Nb and Cu Samples	electron, cavity, vacuum, factory	2258
	S. Lagotzky, G. Müller Bergische Universität Wuppertal, Wuppertal, Germany
	Funding: The work is funded by BMBF project 05H12PX6. Enhanced field emission (EFE) limits the performance of both superconducting and normal conducting high-gradient accelerating structures. Systematic field emission scanning microscopy and correlated SEM/EDX measurements of relevant Nb and Cu samples have revealed particulates and surface irregularities with field enhancement factors b = 10 - 90 as origin of EFE. Based on sufficient emitter statistics, an exponential increase of the emitter number density N with increasing surface field (E) was found. This allows a prediction of the EFE loading of future ILC and CLIC accelerating structures by scaling of N to relevant E and using a weighted integration over the high-field cavity surface. Accordingly, an electropolished (Ra < 300 nm) and dry-ice cleaned (DIC) TESLA-shape 9-cell 1.3 GHz Nb cavity * will still suffer from EFE at Eacc = 35 MV/m (N = 0.3 /cm² at Epeak = 70 MV/m). Moreover, a diamond-turned, chemically etched and DIC 11.2 GHz Cu structure ** will breakdown at Eacc = 100 MV/m (N = 20 /cm² at Epeak = 243 MV/m). Possible improvements, i.e. by emitter processing will be discussed. * ILC Technical Design Report (2013) ** A. Grudiev and W. Wuensch, Proceedings of LINAC2010, Tsukuba, Japan, pp. 211 - 213
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WEPME020	Commissioning of the MICE RF System	operation, power-supply, experiment, cavity	2297
	A.J. Moss, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S.M.H. Alsari Imperial College of Science and Technology, Department of Physics, London, United Kingdom A.J. Dick, K. Ronald, D.C. Speirs, C.G. Whyte USTRAT/SUPA, Glasgow, United Kingdom T. Stanley STFC/RAL, Chilton, Didcot, Oxon, United Kingdom C.J. White STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The Muon Ionisation Cooling Experiment (MICE) is being constructed at Rutherford Appleton Laboratory in the UK. The muon beam will be cooled using multiple hydrogen absorbers then reaccelerated using an RF cavity system operating at 201MHz. This paper describes recent progress in commissioning the amplifier systems at their design operation conditions, installation and operation within the Ionisation Cooling Test Facility (ICTF) as part of the MICE project.
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WEPME021	Solid-state Pulsed Klystron Transmitters	klystron, operation, power-supply, flattop	2300
	K. Schrock, C. Chipman, M.P.J. Gaudreau, B.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: Lawrence Berkeley National Laboratory Daresbury Laboratory Diversified Technologies, Inc. (DTI) is currently building and will deliver in early 2014 two solid-state pulsed klystron transmitters. Though not identical, the units are similar in design, and will be delivered to Lawrence Berkeley National Laboratory (LBNL) and Daresbury Laboratory in England. DTI’s goal across these two projects is to develop a complete package which can subsequently be marketed in the high peak power laboratory transmitter market. The modulator is a pulse transformer-coupled hybrid system, including ancillary klystron components (i.e., focus coil, socket) but not the actual klystron tube. Both systems employ a relatively simple modulator, consisting of an energy storage capacitor, a high voltage series switch, a step-up pulse transformer, and a passive pulse-flattening circuit. This arrangement gives an extremely flat pulse and allows the use of a moderate value of storage capacitor. The DTI switch can open or close as commanded, so the pulse width is adjusted by the gate pulse to the system.
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THPRO035	Improving and Maintaining FEL Beam Stability of the LCLS	FEL, feedback, timing, undulator	2943
	F.-J. Decker, A.L. Benwell, W.S. Colocho, Z. Huang, A. Krasnykh, J.R. Lewandowski, T.J. Maxwell, J. Sheppard, J.L. Turner SLAC, Menlo Park, California, USA
	Funding: *Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented.
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THPRO105	MTCA.4 Module for Cavity and Laser Piezo Operation	laser, cavity, controls, feedback	3140
	K.P. Przygoda, J. Branlard, M. Felber, C. Gerth, M. Heuer, U. Mavrič, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany T. Kozak, P. Prędki TUL-DMCS, Łódź, Poland
	A MicroTCA.4 (MTCA.4) compliant Piezo Driver (DRTM-PZT4)* has been developed to drive piezoelectric-based actuators used in accelerator instrumentation applications. More specifically, it is used for superconducting cavities fine tuning, synchronization of pulsed lasers and stabilization of fiber links. This paper briefly presents the designed system requirements and discusses the main hardware issues. The Piezo Driver performance measurements are also discussed. The first results of the prototype hardware usage for laser locking** to an external RF source and fiber link stabilization are summarized. K. Przygoda et all.,“MTCA.4 Compilant Piezo Driver RTM for Laser Synchronization”,MIXDES'13*U. Mavric et. all, "Precision Synchronization of Optical Lasers based on MTCA.4 Electronics", IBIC'13
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FRXAB01	Trends in RF Technology for Applications to Light Sources with Great Average Power	klystron, operation, rf-amplifier, power-supply	4065
	Ch. Wang NSRRC, Hsinchu, Taiwan
	RF systems are a major part of both the capital and operating costs of contemporary light sources and directly impact their capability, reliability and availability. The RF community has been discussing for many years the best choice of CW RF power source for light sources. In the domain of great average power, the choice is among a klystron, inductive-output tube, and solid-state RF amplifier. Here we review their current development and challenges and offer a perspective from a point of view of operating a light source with high reliability and availability.
	Slides FRXAB01 [4.033 MB]
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Paper

Title

Other Keywords

Page

MOPRO020

FLUKA Simulation of Particle Fluences to ALICE due to LHC Injection Kicker Failures

injection, simulation, kicker, detector

109

N.V. Shetty, C. Bracco, A. Di Mauro, A. Lechner, E. Leogrande, J.A. Uythoven
CERN, Geneva, Switzerland

The counter-rotating beams of the LHC are injected in insertion regions which also accommodate the ALICE and LHCb experiments. An assembly of beam absorbers ensures the protection of machine elements in case of injection kicker failures, which can affect either the injected or the stored beam. In the first years of LHC operation, secondary particle showers due to beam impact on the injection beam stopper caused damage to the MOS injectors of the ALICE silicon drift detector as well as high-voltage trips in other ALICE subdetectors. In this study, we present FLUKA simulations of particle fluences to the ALICE cavern for injection failures encountered during operation. Two different cases are reported, one where the miskicked beam is fully intercepted and one where the beam grazes the beam stopper.

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MOPRO028

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

kicker, flattop, damping, operation

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

kicker, injection, operation, power-supply

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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MOPME051

Turbo Generators for Powering the HV-solenoids at the HESR Electron Cooler

solenoid, electron, power-supply, acceleration

492

A. Hofmann, K. Aulenbacher, M.W. Bruker, J. Dietrich, T. Weilbach
HIM, Mainz, Germany
M.I. Bryzgunov, A.P. Denisov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva
BINP SB RAS, Novosibirsk, Russia

New experiments at the planned 'High Energy Storage Ring' (HESR) require magnetised electron cooling. One of the challenges is the powering of the HV-solenoids, because they are located on HV-sections, which sit on an electrical potential inside a high voltage vessel. We discuss a Multi-MV system where the solenoids are powered by a series of cascade transformers which are in turn supplied by turbogenerators. The usage of SF6 as turbine fluid is desirable from the viewpoint of operational stability and may also lead to energy efficient operation of the turboexpanders since a Organic Rankine-cycle (so-called ORC-process) may be used instead of electrically driven compressors. The paper gives an overview of the turbo generator and ORC project: an introduction, a status report and a road map will be given.

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MOPME071

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

coupling, experiment, plasma, controls

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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MOPME078

Relief of an Electric Field via a Cone Structure

kicker, extraction, booster, vacuum

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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MOPME080

Affordable Short Pulse Marx Modulator

controls, network, flattop, linear-collider

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

kicker, simulation, coupling, impedance

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

controls, damping, operation, flattop

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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MOPRI074

Conceptual Project Relativistic Electron Cooler for FAIR/HESR

electron, proton, acceleration, cathode

774

V.V. Parkhomchuk, M.I. Bryzgunov, A.P. Denisov, V.M. Panasiuk, V.B. Reva
BINP SB RAS, Novosibirsk, Russia
K. Aulenbacher, J. Dietrich
HIM, Mainz, Germany
V. Kamerdzhiev
FZJ, Jülich, Germany

To develop a 4 MeV relativistic electron cooling system for the HESR storage ring, which is part of the future GSI facility FAIR, is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the upgrade to 8 MeV of the relativistic electron cooler is essential for the future Electron Nucleon Collider (ENC@FAIR) project. The basic feature of the design are the power for magnet field coils at accelerating and decelerating column is generated by turbines (one option under investigation in this research group) operated on SF6 gas under pressure

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TUPME039

System Integration of the Demonstration Siemens Electrostatic Accelerator

ion-source, ion, power-supply, experiment

1440

H. von Jagwitz-Biegnitz
JAI, Oxford, United Kingdom
P. Beasley, S. Goßmann-Levchuk, O. Heid
Siemens AG, Erlangen, Germany
D.C. Faircloth
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
R.G. Selway
Inspired Engineering Ltd, Climping, United Kingdom

Siemens has proposed a novel compact DC electrostatic tandem accelerator to produce protons of a few MeV. Siemens is currently building a prototype of the accelerator at the Rutherford Appleton Laboratory. This paper reports on recent progress on the different components of the system as well as the commissioning of the whole machine.

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WEPME004

Prediction of Severe Electron Loading of High-gradient Accelerating Structures based on Field Emission Measurements of Nb and Cu Samples

electron, cavity, vacuum, factory

2258

S. Lagotzky, G. Müller
Bergische Universität Wuppertal, Wuppertal, Germany

Funding: The work is funded by BMBF project 05H12PX6.
Enhanced field emission (EFE) limits the performance of both superconducting and normal conducting high-gradient accelerating structures. Systematic field emission scanning microscopy and correlated SEM/EDX measurements of relevant Nb and Cu samples have revealed particulates and surface irregularities with field enhancement factors b = 10 - 90 as origin of EFE. Based on sufficient emitter statistics, an exponential increase of the emitter number density N with increasing surface field (E) was found. This allows a prediction of the EFE loading of future ILC and CLIC accelerating structures by scaling of N to relevant E and using a weighted integration over the high-field cavity surface. Accordingly, an electropolished (Ra < 300 nm) and dry-ice cleaned (DIC) TESLA-shape 9-cell 1.3 GHz Nb cavity * will still suffer from EFE at Eacc = 35 MV/m (N = 0.3 /cm² at Epeak = 70 MV/m). Moreover, a diamond-turned, chemically etched and DIC 11.2 GHz Cu structure ** will breakdown at Eacc = 100 MV/m (N = 20 /cm² at Epeak = 243 MV/m). Possible improvements, i.e. by emitter processing will be discussed.
* ILC Technical Design Report (2013)
** A. Grudiev and W. Wuensch, Proceedings of LINAC2010, Tsukuba, Japan, pp. 211 - 213

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WEPME020

Commissioning of the MICE RF System

operation, power-supply, experiment, cavity

2297

A.J. Moss, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.M.H. Alsari
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
A.J. Dick, K. Ronald, D.C. Speirs, C.G. Whyte
USTRAT/SUPA, Glasgow, United Kingdom
T. Stanley
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
C.J. White
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The Muon Ionisation Cooling Experiment (MICE) is being constructed at Rutherford Appleton Laboratory in the UK. The muon beam will be cooled using multiple hydrogen absorbers then reaccelerated using an RF cavity system operating at 201MHz. This paper describes recent progress in commissioning the amplifier systems at their design operation conditions, installation and operation within the Ionisation Cooling Test Facility (ICTF) as part of the MICE project.

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WEPME021

Solid-state Pulsed Klystron Transmitters

klystron, operation, power-supply, flattop

2300

K. Schrock, C. Chipman, M.P.J. Gaudreau, B.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: Lawrence Berkeley National Laboratory Daresbury Laboratory
Diversified Technologies, Inc. (DTI) is currently building and will deliver in early 2014 two solid-state pulsed klystron transmitters. Though not identical, the units are similar in design, and will be delivered to Lawrence Berkeley National Laboratory (LBNL) and Daresbury Laboratory in England. DTI’s goal across these two projects is to develop a complete package which can subsequently be marketed in the high peak power laboratory transmitter market. The modulator is a pulse transformer-coupled hybrid system, including ancillary klystron components (i.e., focus coil, socket) but not the actual klystron tube. Both systems employ a relatively simple modulator, consisting of an energy storage capacitor, a high voltage series switch, a step-up pulse transformer, and a passive pulse-flattening circuit. This arrangement gives an extremely flat pulse and allows the use of a moderate value of storage capacitor. The DTI switch can open or close as commanded, so the pulse width is adjusted by the gate pulse to the system.

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THPRO035

Improving and Maintaining FEL Beam Stability of the LCLS

FEL, feedback, timing, undulator

2943

F.-J. Decker, A.L. Benwell, W.S. Colocho, Z. Huang, A. Krasnykh, J.R. Lewandowski, T.J. Maxwell, J. Sheppard, J.L. Turner
SLAC, Menlo Park, California, USA

Funding: *Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented.

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THPRO105

MTCA.4 Module for Cavity and Laser Piezo Operation

laser, cavity, controls, feedback

3140

K.P. Przygoda, J. Branlard, M. Felber, C. Gerth, M. Heuer, U. Mavrič, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
T. Kozak, P. Prędki
TUL-DMCS, Łódź, Poland

A MicroTCA.4 (MTCA.4) compliant Piezo Driver (DRTM-PZT4)* has been developed to drive piezoelectric-based actuators used in accelerator instrumentation applications. More specifically, it is used for superconducting cavities fine tuning, synchronization of pulsed lasers and stabilization of fiber links. This paper briefly presents the designed system requirements and discusses the main hardware issues. The Piezo Driver performance measurements are also discussed. The first results of the prototype hardware usage for laser locking** to an external RF source and fiber link stabilization are summarized.
*K. Przygoda et all.,“MTCA.4 Compilant Piezo Driver RTM for Laser Synchronization”,MIXDES'13**U. Mavric et. all, "Precision Synchronization of Optical Lasers based on MTCA.4 Electronics", IBIC'13

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FRXAB01

Trends in RF Technology for Applications to Light Sources with Great Average Power

klystron, operation, rf-amplifier, power-supply

4065

Ch. Wang
NSRRC, Hsinchu, Taiwan

RF systems are a major part of both the capital and operating costs of contemporary light sources and directly impact their capability, reliability and availability. The RF community has been discussing for many years the best choice of CW RF power source for light sources. In the domain of great average power, the choice is among a klystron, inductive-output tube, and solid-state RF amplifier. Here we review their current development and challenges and offer a perspective from a point of view of operating a light source with high reliability and availability.

Slides FRXAB01 [4.033 MB]

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