Keyword: high-voltage
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MOPA61 Modular Solid-State Switching and Arc Suppression for Vacuum Tube Bias Circuits vacuum, power-supply, pulsed-power, operation 179
  • E.L. Atkinson, T.J. Houlahan, B.E. Jurczyk, R.A. Stubbers
    Starfire Industries LLC, Champaign, USA
  In this work, we present operational and performance data for a solid-state switching circuit that delivers pulsed power at up to 12 kV and 100 A. This circuit, which is comprised of a series configuration of IGBT-based subcircuits, is suitable for driving the high-power vacuum-tube amplifiers that are typically used in RF accelerator systems. Each subcircuit can switch up to 3 kV, and the subcircuits can be stacked in series to extend the overall voltage capabilities of the switch. The circuit is designed to prevent overvoltaging any single transistor during switching transients or faults, regardless of the number of series subcircuits. Further, the circuit also includes the capability for rapid arc detection and suppression. Testing has shown effective switching at up to 100 A at 12 kV and for pulse repetition frequencies and durations in the range of 1-200 Hz and 10-50 µs, respectively. Additionally, the arc suppression circuitry has been shown to reliably limit arcs at 8-12 kV with a quench time of <1 µs and with a total energy of <0.2 J, minimizing the grid erosion in the vacuum-tube during an arc.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA61  
About • Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 20 August 2022 — Issue date ※ 10 September 2022
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TUPA64 Analysis of Resonant Converter Topology for High-Voltage Modulators resonance, operation, impedance, klystron 486
  • M. Sanchez Barrueta, J.T.M. Lyles, M.D.M. Morris
    LANL, Los Alamos, New Mexico, USA
  Funding: Work Supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
At the Los Alamos Neutron Science Center (LANSCE), we are considering various topologies to replace obsolete charging supplies and capacitor banks that provide high-voltage direct-current (DC) power to the 44, 805-MHz klystron modulators that drive the LANSCE Coupled Cavity Linac (CCL). Among the possible replacement topologies is the High Voltage Converter Modulator (HVCM), originally designed at LANSCE for use at the Spallation Neutron Source (SNS), to be used as a pulsed high-voltage power supply for klystron-based RF transmitters. The HVCM topology uses high frequency transformers with resonant LC networks for efficient energy conversion and a frequency dependent gain, which permits the use of frequency modulation as a control variable to afford pulse flattening and excellent regulation as demonstrated at SNS. A mathematical analysis is presented that links the converter resonant tank components to the frequency dependent output behavior of the converter modulator.
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA64  
About • Received ※ 03 August 2022 — Revised ※ 10 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 22 August 2022
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WEPA16 A 500 kV Inverted Geometry Feedthrough for a High Voltage DC Electron Gun gun, electron, power-supply, cathode 651
  • C. Hernandez-Garcia, D.B. Bullard, J.M. Grames, G.G. Palacios Serrano, M. Poelker
    JLab, Newport News, Virginia, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of Science Funding Opportunity LAB 20-2310 award PAMS-254442.
The Continuous Electron Beam Accelerator Facility injector at Jefferson Lab (JLab) utilizes an inverted-geometry ceramic insulator photogun operating at 130 kV direct current to generate spin-polarized electron beams for high-energy nuclear physics experiments. A second photogun delivers 180 keV beam for commissioning a SRF booster in a testbed accelerator, and a larger version delivers 300 keV magnetized beam in a test stand beam line. This contribution reports on the development of an unprecedented inverted-insulator with cable connector for reliably applying 500 kV DC to a future polarized beam photogun, to be designed for operating at 350 kV without field emission. Such a photogun design could then be used for generating a polarized electron beam to drive a spin-polarized positron source as a demonstrator for high energy nuclear physics at JLab. There are no commercial cable connectors that fit the large inverted insulators required for that voltage range. Our proposed concept is based on a modified epoxy receptacle with intervening SF6 layer and a test electrode in a vacuum vessel.
poster icon Poster WEPA16 [6.217 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA16  
About • Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 09 October 2022
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WEPA17 Improved Electrostatic Design of the Jefferson Lab 300 kV DC Photogun and the Minimization of Beam Deflection gun, cathode, electron, laser 655
  • M.A. Mamun, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, G.A. Krafft, M. Poelker, R. Suleiman
    JLab, Newport News, Virginia, USA
  • J.R. Delayen, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga
    ODU, Norfolk, Virginia, USA
  Funding: This work is supported by the Department of Energy, under contract DE-AC05-06OR23177, JSA initiatives fund program, and the Laboratory Directed Research and Development program.
An electron beam with high bunch charge and high repetition rate is required for electron cooling of the ion beam to achieve the high luminosity required for the proposed electron-ion colliders. An improved design of the 300 kV DC high voltage photogun at Jefferson Lab was incorporated toward overcoming the beam loss and space charge current limitation experienced in the original design. To reach the bunch charge goal of ~ few nC within 75 ps bunches, the existing DC high voltage photogun electrodes and anode-cathode gap were modified to increase the longitudinal electric field (Ez) at the photocathode. The anode-cathode gap was reduced to increase the Ez at the photocathode, and the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the geometric asymmetry of the inverted insulator photogun. The electrostatic design and beam dynamics simulations were performed to determine the required modification. Beam-based measurement from the modified gun confirmed the reduction of the beam deflection, which is presented in this contribution.
poster icon Poster WEPA17 [2.973 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA17  
About • Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 05 August 2022 — Issue date ※ 11 August 2022
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WEPA20 High-Gradient Wien Spin Rotators at Jefferson Lab vacuum, electron, operation, gun 662
  • G.G. Palacios Serrano, P.A. Adderley, J.M. Grames, C. Hernandez-Garcia, M. Poelker
    JLab, Newport News, Virginia, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Nuclear physics experiments performed in the Contin-uous Electron Beam Accelerator Facility (CEBAF) at Jefferson Laboratory (JLab) require spin manipulation of electron beams. Two Wien spin rotators in the injector keV region are essential at CEBAF to establish longitudinal polarization at the end station target, and to flip the polarization direction by π rad to rule out false asymmetries. In a Wien filter, the homogeneous and independent electric and magnetic fields, along with the velocity vectors of the electrons that traverse it, form a mutually orthogonal system. The magnitude of the electrostatic field, established by biasing two highly-polished elec-trodes, defines the desired spin angle at the target yet deviates the beam trajectory due to the Lorentz force. The beam trajectory in the Wien is then re-established by adjusting the magnetic field, induced by an electromag-net encasing the device vacuum chamber. This contribu-tion describes the evolution design and high voltage testing of Wien filters for spin manipulation at increased beam energies in the keV injector region, required by high precision parity violation experiments like MOLLER.
poster icon Poster WEPA20 [1.434 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA20  
About • Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 05 September 2022
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WEPA41 Maximizing Output of 3 MeV S-band Industrial Accelerator gun, target, ECR, simulation 723
  • D. Fischer, M. Denney, A.V. Mishin, S. Proskin, J. Roylance, L. Young
    Varex Imaging, Salt Lake City, USA
  Earlier, we have reported on a record-breaking 3-MeV Accelerator Beam Centerline (ABC) built in 2017-2018. An upgraded version of this 3-MeV S-band ABC has been developed at Varex Imaging as a key component for one of the most popular X-ray industrial linear accelerator systems, commonly used for security and NDT applications. Being significantly strained by excessive backstreaming, increasing of the ABC output is a challenging task. We describe these challenges and highlight high power test results. The triode gun and structure design improvements allowed us to raise stable output up to 530 Rad/min/1m at 3 MeV and up to 220 Rad/min/1m at 4.5 MeV with a widely available 2.5-MW/2.7-kW magnetron, while maintaining the spot size at 2 mm.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA41  
About • Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 September 2022
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WEPA50 Initial Development of a High-Voltage Pulse Generator for a Short-Pulse Kicker kicker, flattop, collider, operation 745
  • J. Prager, K.E. Miller, K. Muggli, C. Schmidt, H. Yeager
    EHT, Seattle, Washington, USA
  Funding: This work was funded by a DOE SBIR (DE-SC0021470).
The future Electron Ion Collider, to be located at Brookhaven National Laboratory (BNL), will require a new short-pulse stripline kicker for the 150 MeV energy recovery LINAC. The pulse generator must produce ±50 kV pulses with widths less than 38 ns into a 50° kicker load and with low jitter. The power system must be highly reliable and robust to potential faults. Eagle Harbor Technologies (EHT), Inc. is leveraging our previous experience developing inductive adders to produce a high-voltage pulse generator that can meet the needs of the BNL kickers. In this program, EHT designed a single inductive adder stage and demonstrated the challenging pulse characteristics including fast rise and fall times, low jitter, and flattop stability while operating at the full current (1 kA). EHT will present the development status and output waveforms.
poster icon Poster WEPA50 [1.118 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA50  
About • Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 12 August 2022
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