IPAC2018 - List of Keywords (high-voltage)

Paper	Title	Other Keywords	Page
MOPMF070	High Voltage Design for the Electrostatic Septum for the Mu2e Beam Resonant Extraction	cathode, vacuum, simulation, extraction	289
	M.L. Alvarez, C.C. Jensen, D.K. Morris, V.P. Nagaslaev, H. Pham, D.G. Tinsley Fermilab, Batavia, Illinois, USA
	Two electrostatic septa (ESS) are being designed for the slow extraction of 8GeV proton beam for the Mu2e experiment at Fermilab. Special attention is given to the high voltage components that affect the performance of the septa. The components under consideration are the high voltage (HV) feedthrough, cathode standoff (CS), and clearing electrode ceramic standoffs (CECS). Previous experience with similar HV systems at Fermilab was used to define the evaluation criteria of the design of the high voltage components. Using electric field simulation software, high E-field intensities on the components and integrated field strength along the surface of the dielectric material were minimized. Here we discuss the limitations found and improvements made based on those studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF070
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TUPML071	Experimental Performance of the Chopper for the ESS Linac	electron, linac, experiment, proton	1709
	G. Torrisi, L. Allegra, A.C. Caruso, G. Castro, L. Celona, G. Gallo, S. Gammino, O. Leonardi, A. Longhitano, D. Mascali, L. Neri, S. Passarello, G. Sorbello INFN/LNS, Catania, Italy
	At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS) the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. The ESS requires a high intensity proton beam (74 mA pulsed at 14 Hz of repetition rate), with fast Beam pulse rise/fall time (< 20 μs). In order to meet the project requirement, an electrostatic chopping system has been used in the Low Energy Beam Transport (LEBT). The design of the control system was done also to be the main element of the fast beam abort system and taking into account the radiation issue in the accelerator tunnel. This paper describes the performances of the chopper. The experimentally-achieved rise/fall times of the beam pulses measured by using an AC Current Transformer (ACCT) at the end of the LEBT collimator, are presented. An experimental investigation of the effects of different amounts and types of gas injected into the LEBT (for the sake of space charge compensation) has been carried out with respect to the beam and chopper parameters.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML071
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WEYGBF4	Development of a Solid-State Pulse Generator Driving Kicker Magnets for a Novel Injection System of a Low Emittance Storage Ring	kicker, injection, timing, storage-ring	1804
	T. Inagaki, H. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan H. Akikawa, K. Sato Nihon Koshuha Co. Ltd, Yokohama, Japan K. Fukami, C. Kondo, S. Takano Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan
	Funding: Funded by MEXT Japan A next generation electron storage ring represented by a diffraction-limited light source pursues an extremely low emittance leading to a small dynamic aperture and short beam lifetime. The top-up injection is hence indispensable to keep the stored beam current. The beam orbit fluctuation caused by the injection magnets should seriously obstruct utilization of an electron beam with sharp transverse profile. In order to solve these problems, a novel off-axis in-vacuum beam injection system was proposed. In the system, twin kicker magnets driven by a single solid-state pulsed power supply to launch a linear pi- bump orbit is the key to suppress the horizontal orbit fluctuation down to a level of several microns. Here, a big challenge is to achieve the magnetic field identity of the two kickers within an accuracy of 0.1%. This presentation overviews the proposed injection system and reports the development status focusing on the solid-state pulse generator.
	Slides WEYGBF4 [3.062 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBF4
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WEPAF025	Fast Intensity Monitor Based on Channeltron Electron Multiplier	electron, electronics, proton, detector	1873
	G.M.A. Calvi, V. Lante, L. Lanzavecchia, G. Magro, A. Parravicini, E. Rojatti, C. Viviani CNAO Foundation, Milan, Italy
	The paper concerns the Fast Intensity Monitor (FIM) designed for the CNAO (Centro Nazionale di Adroterapia Oncologica), the Italian facility of Oncological Hadrontherapy. The FIM detector has been designed with the purpose of having a continuous and non-destructive measurement of the beam intensity in the High Energy Beam Transfer (HEBT) line. The passage of the beam through a thin aluminum foil produces secondary electrons whose yield depends on beam species (protons or carbon ions), intensity and energy. Secondary electrons are focused on the Channeltron Electron Multiplier (CEM) input, multiplied and sensed over a precision resistor. In order to minimize the perturbation to the beam, the foil is grounded and the read out electronics is floating. This makes electronics design harder but it is a key point to make FIM use possible continuously even during patients treatment. Measurements performed with the FIM are discussed and checked against reference detectors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF025
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WEPAF053	Status and Commissioning of the European XFEL Beam Loss Monitor System	FEL, electron, controls, hardware	1940
	T. Wamsat, T. Lensch, P.A. Smirnov DESY, Hamburg, Germany
	The European XFEL MTCA based Beam Loss Monitor System (BLM) is composed of about 450 monitors, which are part of the Machine Protection System (MPS). The BLMs detect losses of the electron beam, in order to protect accelerator components from damage and excessive activation, in particular the undulators, since they are made of permanent magnets. Also each cold accelerating module is equipped with a BLM to measure the sudden onset of field emission (dark current) in cavities. In addition some BLMs are used as detectors for wire- scanners. Experience from the already running BLM system in FLASH2 which is based on the same technology, led to a fast implementation of the system in the XFEL. Further firmware and server developments related to alarm generation and handling are ongoing. The BLM systems structure, the current status and the different possibilities to trigger alarms which stop the electron beam will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF053
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WEPMF063	Thyratron Replacement*	operation, klystron, linear-collider, collider	2512
	I. Roth, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: Funded under US DOE grant no. DE-SC0011292. Thyratrons are typically used as the switch in high power, short pulse modulators with pulse-forming networks. However, thyratrons have a lifetime of only ten to twenty thousand hours, their reservoir heater voltage needs to be adjusted periodically, and reduced overall demand has led multiple thyratron vendors to slow or cease production. In contrast, solid-state switches have a much longer lifetime, need no maintenance, and are based on widely-available commercial items. Despite these advantages, solid-state devices have not historically seen use, due to limited voltage, current, and risetime. Diversified Technologies, Inc. (DTI) has removed this barrier, having developed, built, and tested a thyratron-replacement switch for SLAC based on an array of series and parallel-connected commercial insulated-gate bipolar transistors (IGBTs). This switch has demonstrated operation at very high voltage and current, meeting the full specifications required by SLAC to completely replace (form-fit-function-interface) the L-4888 thyratron: 48 kV, 6.3 kA, and 1 μs risetime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF063
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WEPMF064	Daresbury Laboratory Short Pulse Klystron Modulators	klystron, operation, power-supply, factory	2515
	C. Chipman, M.P.J. Gaudreau, L. Jashari, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA S.A. Griffiths, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.J. Zhang Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
	Diversified Technologies, Inc. (DTI) has developed a unique short pulse klystron modulator system for the Compact Linear Advanced Research Accelerator (CLARA) Project at Daresbury Laboratory. One unit has been delivered and three more are on contract. This system is based on the combination of a high voltage solid-state switch, with a conventional 1:7 pulse transformer, and a passive pulse corrector with automated adjustment. This unique passive circuitry delivers the extremely flat output pulse required for advanced accelerator applications. The CLARA modulators share design elements with previous DTI modulators which provides both a lower cost and easier to maintain system. The modulators are designed to pulse 80 MW-class klystrons at an avg power of 250 kW and provides adjustable high efficiency operation in the 45 kV to 450 kV range for currents up to 545 A and pulse lengths of 1.5 to 4.0 μs. One key objective of modulator development is optimization of voltage flatness (± 0.02 %), stability (± 0.05 %), and reproducibility (± 0.05 %).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF064
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WEPMF076	First Prototype Inductive Adder for the FCC Injection	kicker, injection, distributed, impedance	2553
	D. Woog, M.J. Barnes, A. Ferrero Colomo, J. Holma, T. Kramer CERN, Geneva, Switzerland
	A highly reliable kicker system is required as part of the injection for the FCC. A significant weak point of conventional kicker systems is often the pulse generator, where a Pulse Forming Network/Line (PFN/PFL) is discharged through a thyratron switch to generate the current pulse for the kicker magnet. This design has several disadvantages: in particular the occasional erratic turn-on of the switch which cannot be accepted for the FCC. A potential replacement is the inductive adder (IA) that uses semiconductor switches and distributed capacitors as energy storage. The modular design, low maintenance and high flexibility make the IA a very interesting alternative. In addition, the ability to both turn-on and off the current also permits the replacement of PFN/PFL by the capacitors. A first FCC prototype IA, capable of generating 9 kV and 2.4 kA pulses, has been designed and built at CERN. It will be upgrade to a full-scale prototype (15 kV, 2.4 kA) in 2018. This paper presents measurement results from the 9 kV prototype and outlines the conceptual changes and expected performance of the 15 kV prototype.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF076
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THPAK021	Design of High Resolution Mass Spectrometer for SPES	dipole, HOM, simulation, emittance	3252
	M. Comunian, C. Baltador, L. Bellan, M. Cavenago, A. Pisent INFN/LNL, Legnaro (PD), Italy E. Khabibullina ITEP, Moscow, Russia E. Khabibullina MEPhI, Moscow, Russia
	Within the framework of the SPES (Selective Production of Exotic Species) project at National Institute of Nuclear Physics (INFN laboratory, Legnaro, Italy) the High Resolution Mass Spectrometer (HRMS) will be build. HRMS needs to provide full separation of the ions with mass resolution 1/20000 for the following breeding and acceleration on ALPI Linac. In this article the main design choice of the HRMS and of the transport channel will be reported.
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THPAL055	A Novel High Step-down DC-DC Converter with Isolated Transformer and Switched Capacitor Techniques for Corrector Magnet Bulk Power in Taiwan Photon Source	ISOL, power-supply, simulation, operation	3769
	Y.S. Wong, K.-B. Liu NSRRC, Hsinchu, Taiwan J.F. Chen NCKU, Tainan city, Taiwan
	In this study, a high step down DC-DC converter was successfully integrated using switch capacitor and isolated transformer techniques. Switching capacitor techniques has use of capacitor parallel energy storage and series release of the way to improve the voltage conversion ratio. In addition, the output voltage ripple will be smaller due to the input current being continuous, the inductance is an element to prevent a surge current. The isolated transformer techniques has use of inductor coil turns ratio to achieve high conversion ratio. But, the leakage inductor and parasitic capacitance on the power switch will be resonant to generate a surge voltage spike when the power switch S is turned off. So that, additional a passive clamp circuit, energy of leakage inductor will be recycled to clamp capacitor and voltage stress of main power switch. The power switch S can be selected a lower Rds(on) components and reduce the conduction losses to improve power converter efficiency. Step down mode operation principle and steady-state analysis were discussed in this paper. Finally, simulation and prototype circuit is implemented in this laboratory to verify the performance, the step-down DC-DC converter is input voltage 400-V, output voltage 48-V and output power 960-W.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL055
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THPAL102	Design a High Power Pulse Transformer for C-band Klystron Modulator	flattop, klystron, plasma, FEL	3875
	Y.F. Liu, Z.H. Chen, M. Gu, Y. Wu, Q. Yuan, X.X. Zhou SINAP, Shanghai, People's Republic of China
	Shanghai soft X-ray Free Electron Lasers (SXFEL) first uses C band accelerator structure to accelerate electrons at SINAP. SXFEL is an X-ray free electron laser facility, which requests very stable amplitude stability and very tight tolerances of phase jitter. 50MW C-band klystron and 110MW modulator is used to provide power supply for accelerator structure. Typical specifications of the modulator are peak beam voltage 350KV, peak beam current 320A, 10Hz repetition rate, 3us flat-top pulse width. In order to meet these demands, we developed a reliable and stable high power pulse transformer. In this paper, the analysis and design of high power pulse transformer for C band klystron modulator are presented. The methods of shortening rise time, diminishing droop and diminishing flat top oscillation are highlighted. Detailed design, simulation and relevant experimental results are given. The relevant experiments show that this pulse transformer can meet the requirement of 50MW C band klystron.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL102
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THPMK088	Low Emittance Thermionic Electron Gun at SLRI	electron, gun, cathode, emittance	4509
	K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak SLRI, Nakhon Ratchasima, Thailand
	The Synchrotron Light Research Institute (SLRI) has developed a new thermionic electron gun producing low emittance electron beam for the future upgrade of the existing one. The thermionic cathode made of a CeB6 single crystal is selected due to its properties providing high electron beam current, uniform current density, and high resistance to contamination. In addition, the CeB6 cathode of 3 mm in diameter can produce up to a few Amperes of electron beam current. The electron gun is pulsed at 500 kV with a few microseconds wide to avoid high voltage breakdown as well as to reduce space charge effect resulting in the emittance growth of the extracted electron beam. The preliminary simulation and design of the electron gun together with the high voltage system are described in the paper.
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THPMK110	300 kV DC High Voltage Photogun with Inverted Insulator Geometry and CsK2sb Photocathode	cathode, gun, emittance, laser	4571
	Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, M.G. Tiefenback, S. Zhang JLab, Newport News, Virginia, USA G.A. Krafft, S.A.K. Wijethunga ODU, Norfolk, Virginia, USA
	Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177 A compact DC high voltage photogun with inverted-insulator geometry was designed, built and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This presentation describes key electrostatic design features of the photogun with accompanying emittance measurements obtained across the entire photocathode surface that speak to field non-uniformity within the cathode/anode gap. A summary of initial photocathode lifetime measurements at beam currents up to 4.5 mA is also presented.
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THPML059	Re-Commissioning the Front End Test Stand Negative Hydrogen Ion Source, Beam Transport and Interlocks	ion-source, rfq, vacuum, MMI	4769
	S.R. Lawrie, R.E. Abel, M. Dudman, D.C. Faircloth, A.P. Letchford, J.H. Macgregor, M. Perkins, T. M. Sarmento, R.C. Searle, M. Whitehead, T. Wood STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The front end test stand (FETS) is a demonstrator for a future high intensity, high duty factor negative hydrogen (H') ion injector. With the radio-frequency quadrupole (RFQ) nearing installation, the ion source has been re-commissioned in preparation for long-term operation. The 3 MeV beam exceeds the radio-activation energy of common engineering materials, so radiation shielding has been erected. A new interlocking scheme has been signed-off which integrates the existing ion source high voltage area with the new shielding access points, to ensure that the machine can operate safely during beam production. The existing vacuum arrangement has been extended to in-clude the RFQ and medium energy beam transport (MEBT) line. A new programmable logic controller (PLC) has been built to operate the entire vacuum chain. The ion source high voltage equipment has been upgraded to minimise both spark rate and intensity. A collimating aperture and Faraday cup have been installed after the low energy beam transport (LEBT) section to ensure the beam is well aligned for injection into the RFQ. Re-commissioning the ion source has given a rugged shakedown of all these new systems before beam is required for the RFQ. *scott.lawrie@stfc.ac.uk
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THPML080	Preliminary Results of a New High Brightness H⁻ Ion Source Developed at TRIUMF	emittance, ion-source, extraction, TRIUMF	4839
	K. Jayamanna, F. Ames, Y. Bylinskii, J.Y. Cheng, M. Lovera, M. Minato TRIUMF, Vancouver, Canada
	This paper describes the preliminary results of a high brightness ion source developed at TRIUMF, which is capable of producing a negative hydrogen ion beam (H⁻) of up to 5 mA of direct current. A 1.7 mm.mrad and 5 mm.mrad emittance(rms) is achieved for 500 uA and for 1 mA H-, respectively. Characteristics as well as a brief description regarding extraction issues of the source to date are also presented.
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THPML100	A High Voltage Feedforward Subsystem of Low Level RF System for the High Power RF System	LLRF, low-level-rf, experiment, controls	4898
	Z.Y. Lin, Y. C. Du, H.Q. Feng, W.-H. Huang, CY. Song, C.-X. Tang, Y.L. Xu, J. Yang TUB, Beijing, People's Republic of China G. Huang LBNL, Berkeley, California, USA
	The Low Level Radio Frequency control (LLRF) system measures the RF signals from the accelerator tube, compares it with the phase reference received from the timing distribution system, and provides the drive signal to the high power RF system to provide synchronized RF voltage to the electron beam. Usually, the LLRF system can achieve a ~50 fs RMS phase jitter which is limited by the microwave devices. The phase noise arise from the high voltage variation of the high power system will significantly increase phase noise from low level RF signal to high power RF. A high voltage feed forward subsystem is proposed to deal with the phase noise caused by the high voltage jitter of the modulator. The demo system is depolyed in Thomson scattering X-ray source (TTX).and the primary experiment result anaylse is discussed.
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Paper

Title

Other Keywords

Page

MOPMF070

High Voltage Design for the Electrostatic Septum for the Mu2e Beam Resonant Extraction

cathode, vacuum, simulation, extraction

289

M.L. Alvarez, C.C. Jensen, D.K. Morris, V.P. Nagaslaev, H. Pham, D.G. Tinsley
Fermilab, Batavia, Illinois, USA

Two electrostatic septa (ESS) are being designed for the slow extraction of 8GeV proton beam for the Mu2e experiment at Fermilab. Special attention is given to the high voltage components that affect the performance of the septa. The components under consideration are the high voltage (HV) feedthrough, cathode standoff (CS), and clearing electrode ceramic standoffs (CECS). Previous experience with similar HV systems at Fermilab was used to define the evaluation criteria of the design of the high voltage components. Using electric field simulation software, high E-field intensities on the components and integrated field strength along the surface of the dielectric material were minimized. Here we discuss the limitations found and improvements made based on those studies.

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TUPML071

Experimental Performance of the Chopper for the ESS Linac

electron, linac, experiment, proton

1709

G. Torrisi, L. Allegra, A.C. Caruso, G. Castro, L. Celona, G. Gallo, S. Gammino, O. Leonardi, A. Longhitano, D. Mascali, L. Neri, S. Passarello, G. Sorbello
INFN/LNS, Catania, Italy

At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS) the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. The ESS requires a high intensity proton beam (74 mA pulsed at 14 Hz of repetition rate), with fast Beam pulse rise/fall time (< 20 μs). In order to meet the project requirement, an electrostatic chopping system has been used in the Low Energy Beam Transport (LEBT). The design of the control system was done also to be the main element of the fast beam abort system and taking into account the radiation issue in the accelerator tunnel. This paper describes the performances of the chopper. The experimentally-achieved rise/fall times of the beam pulses measured by using an AC Current Transformer (ACCT) at the end of the LEBT collimator, are presented. An experimental investigation of the effects of different amounts and types of gas injected into the LEBT (for the sake of space charge compensation) has been carried out with respect to the beam and chopper parameters.

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WEYGBF4

Development of a Solid-State Pulse Generator Driving Kicker Magnets for a Novel Injection System of a Low Emittance Storage Ring

kicker, injection, timing, storage-ring

1804

T. Inagaki, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
H. Akikawa, K. Sato
Nihon Koshuha Co. Ltd, Yokohama, Japan
K. Fukami, C. Kondo, S. Takano
Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan

Funding: Funded by MEXT Japan
A next generation electron storage ring represented by a diffraction-limited light source pursues an extremely low emittance leading to a small dynamic aperture and short beam lifetime. The top-up injection is hence indispensable to keep the stored beam current. The beam orbit fluctuation caused by the injection magnets should seriously obstruct utilization of an electron beam with sharp transverse profile. In order to solve these problems, a novel off-axis in-vacuum beam injection system was proposed. In the system, twin kicker magnets driven by a single solid-state pulsed power supply to launch a linear pi- bump orbit is the key to suppress the horizontal orbit fluctuation down to a level of several microns. Here, a big challenge is to achieve the magnetic field identity of the two kickers within an accuracy of 0.1%. This presentation overviews the proposed injection system and reports the development status focusing on the solid-state pulse generator.

Slides WEYGBF4 [3.062 MB]

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WEPAF025

Fast Intensity Monitor Based on Channeltron Electron Multiplier

electron, electronics, proton, detector

1873

G.M.A. Calvi, V. Lante, L. Lanzavecchia, G. Magro, A. Parravicini, E. Rojatti, C. Viviani
CNAO Foundation, Milan, Italy

The paper concerns the Fast Intensity Monitor (FIM) designed for the CNAO (Centro Nazionale di Adroterapia Oncologica), the Italian facility of Oncological Hadrontherapy. The FIM detector has been designed with the purpose of having a continuous and non-destructive measurement of the beam intensity in the High Energy Beam Transfer (HEBT) line. The passage of the beam through a thin aluminum foil produces secondary electrons whose yield depends on beam species (protons or carbon ions), intensity and energy. Secondary electrons are focused on the Channeltron Electron Multiplier (CEM) input, multiplied and sensed over a precision resistor. In order to minimize the perturbation to the beam, the foil is grounded and the read out electronics is floating. This makes electronics design harder but it is a key point to make FIM use possible continuously even during patients treatment. Measurements performed with the FIM are discussed and checked against reference detectors.

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WEPAF053

Status and Commissioning of the European XFEL Beam Loss Monitor System

FEL, electron, controls, hardware

1940

T. Wamsat, T. Lensch, P.A. Smirnov
DESY, Hamburg, Germany

The European XFEL MTCA based Beam Loss Monitor System (BLM) is composed of about 450 monitors, which are part of the Machine Protection System (MPS). The BLMs detect losses of the electron beam, in order to protect accelerator components from damage and excessive activation, in particular the undulators, since they are made of permanent magnets. Also each cold accelerating module is equipped with a BLM to measure the sudden onset of field emission (dark current) in cavities. In addition some BLMs are used as detectors for wire- scanners. Experience from the already running BLM system in FLASH2 which is based on the same technology, led to a fast implementation of the system in the XFEL. Further firmware and server developments related to alarm generation and handling are ongoing. The BLM systems structure, the current status and the different possibilities to trigger alarms which stop the electron beam will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF053

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WEPMF063

Thyratron Replacement*

operation, klystron, linear-collider, collider

2512

I. Roth, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: Funded under US DOE grant no. DE-SC0011292.
Thyratrons are typically used as the switch in high power, short pulse modulators with pulse-forming networks. However, thyratrons have a lifetime of only ten to twenty thousand hours, their reservoir heater voltage needs to be adjusted periodically, and reduced overall demand has led multiple thyratron vendors to slow or cease production. In contrast, solid-state switches have a much longer lifetime, need no maintenance, and are based on widely-available commercial items. Despite these advantages, solid-state devices have not historically seen use, due to limited voltage, current, and risetime. Diversified Technologies, Inc. (DTI) has removed this barrier, having developed, built, and tested a thyratron-replacement switch for SLAC based on an array of series and parallel-connected commercial insulated-gate bipolar transistors (IGBTs). This switch has demonstrated operation at very high voltage and current, meeting the full specifications required by SLAC to completely replace (form-fit-function-interface) the L-4888 thyratron: 48 kV, 6.3 kA, and 1 μs risetime.

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WEPMF064

Daresbury Laboratory Short Pulse Klystron Modulators

klystron, operation, power-supply, factory

2515

C. Chipman, M.P.J. Gaudreau, L. Jashari, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA
S.A. Griffiths, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.J. Zhang
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China

Diversified Technologies, Inc. (DTI) has developed a unique short pulse klystron modulator system for the Compact Linear Advanced Research Accelerator (CLARA) Project at Daresbury Laboratory. One unit has been delivered and three more are on contract. This system is based on the combination of a high voltage solid-state switch, with a conventional 1:7 pulse transformer, and a passive pulse corrector with automated adjustment. This unique passive circuitry delivers the extremely flat output pulse required for advanced accelerator applications. The CLARA modulators share design elements with previous DTI modulators which provides both a lower cost and easier to maintain system. The modulators are designed to pulse 80 MW-class klystrons at an avg power of 250 kW and provides adjustable high efficiency operation in the 45 kV to 450 kV range for currents up to 545 A and pulse lengths of 1.5 to 4.0 μs. One key objective of modulator development is optimization of voltage flatness (± 0.02 %), stability (± 0.05 %), and reproducibility (± 0.05 %).

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WEPMF076

First Prototype Inductive Adder for the FCC Injection

kicker, injection, distributed, impedance

2553

D. Woog, M.J. Barnes, A. Ferrero Colomo, J. Holma, T. Kramer
CERN, Geneva, Switzerland

A highly reliable kicker system is required as part of the injection for the FCC. A significant weak point of conventional kicker systems is often the pulse generator, where a Pulse Forming Network/Line (PFN/PFL) is discharged through a thyratron switch to generate the current pulse for the kicker magnet. This design has several disadvantages: in particular the occasional erratic turn-on of the switch which cannot be accepted for the FCC. A potential replacement is the inductive adder (IA) that uses semiconductor switches and distributed capacitors as energy storage. The modular design, low maintenance and high flexibility make the IA a very interesting alternative. In addition, the ability to both turn-on and off the current also permits the replacement of PFN/PFL by the capacitors. A first FCC prototype IA, capable of generating 9 kV and 2.4 kA pulses, has been designed and built at CERN. It will be upgrade to a full-scale prototype (15 kV, 2.4 kA) in 2018. This paper presents measurement results from the 9 kV prototype and outlines the conceptual changes and expected performance of the 15 kV prototype.

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THPAK021

Design of High Resolution Mass Spectrometer for SPES

dipole, HOM, simulation, emittance

3252

M. Comunian, C. Baltador, L. Bellan, M. Cavenago, A. Pisent
INFN/LNL, Legnaro (PD), Italy
E. Khabibullina
ITEP, Moscow, Russia
E. Khabibullina
MEPhI, Moscow, Russia

Within the framework of the SPES (Selective Production of Exotic Species) project at National Institute of Nuclear Physics (INFN laboratory, Legnaro, Italy) the High Resolution Mass Spectrometer (HRMS) will be build. HRMS needs to provide full separation of the ions with mass resolution 1/20000 for the following breeding and acceleration on ALPI Linac. In this article the main design choice of the HRMS and of the transport channel will be reported.

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THPAL055

A Novel High Step-down DC-DC Converter with Isolated Transformer and Switched Capacitor Techniques for Corrector Magnet Bulk Power in Taiwan Photon Source

ISOL, power-supply, simulation, operation

3769

Y.S. Wong, K.-B. Liu
NSRRC, Hsinchu, Taiwan
J.F. Chen
NCKU, Tainan city, Taiwan

In this study, a high step down DC-DC converter was successfully integrated using switch capacitor and isolated transformer techniques. Switching capacitor techniques has use of capacitor parallel energy storage and series release of the way to improve the voltage conversion ratio. In addition, the output voltage ripple will be smaller due to the input current being continuous, the inductance is an element to prevent a surge current. The isolated transformer techniques has use of inductor coil turns ratio to achieve high conversion ratio. But, the leakage inductor and parasitic capacitance on the power switch will be resonant to generate a surge voltage spike when the power switch S is turned off. So that, additional a passive clamp circuit, energy of leakage inductor will be recycled to clamp capacitor and voltage stress of main power switch. The power switch S can be selected a lower Rds(on) components and reduce the conduction losses to improve power converter efficiency. Step down mode operation principle and steady-state analysis were discussed in this paper. Finally, simulation and prototype circuit is implemented in this laboratory to verify the performance, the step-down DC-DC converter is input voltage 400-V, output voltage 48-V and output power 960-W.

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THPAL102

Design a High Power Pulse Transformer for C-band Klystron Modulator

flattop, klystron, plasma, FEL

3875

Y.F. Liu, Z.H. Chen, M. Gu, Y. Wu, Q. Yuan, X.X. Zhou
SINAP, Shanghai, People's Republic of China

Shanghai soft X-ray Free Electron Lasers (SXFEL) first uses C band accelerator structure to accelerate electrons at SINAP. SXFEL is an X-ray free electron laser facility, which requests very stable amplitude stability and very tight tolerances of phase jitter. 50MW C-band klystron and 110MW modulator is used to provide power supply for accelerator structure. Typical specifications of the modulator are peak beam voltage 350KV, peak beam current 320A, 10Hz repetition rate, 3us flat-top pulse width. In order to meet these demands, we developed a reliable and stable high power pulse transformer. In this paper, the analysis and design of high power pulse transformer for C band klystron modulator are presented. The methods of shortening rise time, diminishing droop and diminishing flat top oscillation are highlighted. Detailed design, simulation and relevant experimental results are given. The relevant experiments show that this pulse transformer can meet the requirement of 50MW C band klystron.

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THPMK088

Low Emittance Thermionic Electron Gun at SLRI

electron, gun, cathode, emittance

4509

K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak
SLRI, Nakhon Ratchasima, Thailand

The Synchrotron Light Research Institute (SLRI) has developed a new thermionic electron gun producing low emittance electron beam for the future upgrade of the existing one. The thermionic cathode made of a CeB6 single crystal is selected due to its properties providing high electron beam current, uniform current density, and high resistance to contamination. In addition, the CeB6 cathode of 3 mm in diameter can produce up to a few Amperes of electron beam current. The electron gun is pulsed at 500 kV with a few microseconds wide to avoid high voltage breakdown as well as to reduce space charge effect resulting in the emittance growth of the extracted electron beam. The preliminary simulation and design of the electron gun together with the high voltage system are described in the paper.

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THPMK110

300 kV DC High Voltage Photogun with Inverted Insulator Geometry and CsK2sb Photocathode

cathode, gun, emittance, laser

4571

Y.W. Wang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, M.G. Tiefenback, S. Zhang
JLab, Newport News, Virginia, USA
G.A. Krafft, S.A.K. Wijethunga
ODU, Norfolk, Virginia, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
A compact DC high voltage photogun with inverted-insulator geometry was designed, built and operated reliably at 300 kV bias voltage using alkali-antimonide photocathodes. This presentation describes key electrostatic design features of the photogun with accompanying emittance measurements obtained across the entire photocathode surface that speak to field non-uniformity within the cathode/anode gap. A summary of initial photocathode lifetime measurements at beam currents up to 4.5 mA is also presented.

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THPML059

Re-Commissioning the Front End Test Stand Negative Hydrogen Ion Source, Beam Transport and Interlocks

ion-source, rfq, vacuum, MMI

4769

S.R. Lawrie, R.E. Abel, M. Dudman, D.C. Faircloth, A.P. Letchford, J.H. Macgregor, M. Perkins, T. M. Sarmento, R.C. Searle, M. Whitehead, T. Wood
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The front end test stand (FETS) is a demonstrator for a future high intensity, high duty factor negative hydrogen (H') ion injector. With the radio-frequency quadrupole (RFQ) nearing installation, the ion source has been re-commissioned in preparation for long-term operation. The 3 MeV beam exceeds the radio-activation energy of common engineering materials, so radiation shielding has been erected. A new interlocking scheme has been signed-off which integrates the existing ion source high voltage area with the new shielding access points, to ensure that the machine can operate safely during beam production. The existing vacuum arrangement has been extended to in-clude the RFQ and medium energy beam transport (MEBT) line. A new programmable logic controller (PLC) has been built to operate the entire vacuum chain. The ion source high voltage equipment has been upgraded to minimise both spark rate and intensity. A collimating aperture and Faraday cup have been installed after the low energy beam transport (LEBT) section to ensure the beam is well aligned for injection into the RFQ. Re-commissioning the ion source has given a rugged shakedown of all these new systems before beam is required for the RFQ.
*scott.lawrie@stfc.ac.uk

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THPML080

Preliminary Results of a New High Brightness H⁻ Ion Source Developed at TRIUMF

emittance, ion-source, extraction, TRIUMF

4839

K. Jayamanna, F. Ames, Y. Bylinskii, J.Y. Cheng, M. Lovera, M. Minato
TRIUMF, Vancouver, Canada

This paper describes the preliminary results of a high brightness ion source developed at TRIUMF, which is capable of producing a negative hydrogen ion beam (H⁻) of up to 5 mA of direct current. A 1.7 mm.mrad and 5 mm.mrad emittance(rms) is achieved for 500 uA and for 1 mA H-, respectively. Characteristics as well as a brief description regarding extraction issues of the source to date are also presented.

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THPML100

A High Voltage Feedforward Subsystem of Low Level RF System for the High Power RF System

LLRF, low-level-rf, experiment, controls

4898

Z.Y. Lin, Y. C. Du, H.Q. Feng, W.-H. Huang, CY. Song, C.-X. Tang, Y.L. Xu, J. Yang
TUB, Beijing, People's Republic of China
G. Huang
LBNL, Berkeley, California, USA

The Low Level Radio Frequency control (LLRF) system measures the RF signals from the accelerator tube, compares it with the phase reference received from the timing distribution system, and provides the drive signal to the high power RF system to provide synchronized RF voltage to the electron beam. Usually, the LLRF system can achieve a ~50 fs RMS phase jitter which is limited by the microwave devices. The phase noise arise from the high voltage variation of the high power system will significantly increase phase noise from low level RF signal to high power RF. A high voltage feed forward subsystem is proposed to deal with the phase noise caused by the high voltage jitter of the modulator. The demo system is depolyed in Thomson scattering X-ray source (TTX).and the primary experiment result anaylse is discussed.

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