Electrostatic design and conditioning of a triple point junction shield for a –200 kV DC high voltage photogun [Electrostatic design of a triple point junction shield for a -200 kV DC high voltage photogun using COMSOL]

Palacios-Serrano, Gabriel G.; Hannon, Fay E.; Hernandez-Garcia, Carlos; Poelker, Matt; Baumgart, Helmut

doi:10.1063/1.5048700

Title: Electrostatic design and conditioning of a triple point junction shield for a –200 kV DC high voltage photogun [Electrostatic design of a triple point junction shield for a -200 kV DC high voltage photogun using COMSOL]

Abstract

Nuclear physics experiments performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at the Jefferson Lab require a DC high voltage photogun to generate polarized electron beams from GaAs photocathodes. The photogun uses a tapered ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. Increasing the operating voltage from nominal –130 kV to –200 kV will provide lower beam emittance, better transmission through injector apertures, and improved photocathode lifetime. This desire to increase the photogun operating voltage led to the design of a triple-point-junction shield electrode which minimizes the electric field at the delicate insulator-metal-vacuum interface and linearizes the potential across the insulator, thus reducing the risk of arcing along the ceramic insulator. Furthermore, this work describes the results obtained using COMSOL® electrostatic-field simulation software and presents the high voltage conditioning results of the upgraded –200 kV CEBAF photogun.

Authors:

Palacios-Serrano, Gabriel G. ^[1]; Hannon, Fay E. ^[2]; Hernandez-Garcia, Carlos ^[2];

^[2]; Baumgart, Helmut ^[2]

Old Dominion Univ., Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

Publication Date:: Wed Oct 03 00:00:00 EDT 2018

Research Org.:: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Nuclear Physics (NP)

OSTI Identifier:: 1489811

Alternate Identifier(s):: OSTI ID: 1475477

Report Number(s):: JLAB-ACC-18-2842; DOE/OR/23177-4563
Journal ID: ISSN 0034-6748

Grant/Contract Number:: AC05-06OR23177

Resource Type:: Accepted Manuscript

Journal Name:: Review of Scientific Instruments

Additional Journal Information:: Journal Volume: 89; Journal Issue: 10; Journal ID: ISSN 0034-6748

Publisher:: American Institute of Physics (AIP)

Country of Publication:: United States

Language:: English

Subject:: 47 OTHER INSTRUMENTATION

Citation Formats


                    Palacios-Serrano, Gabriel G., Hannon, Fay E., Hernandez-Garcia, Carlos, Poelker, Matt, and Baumgart, Helmut. Electrostatic design and conditioning of a triple point junction shield for a –200 kV DC high voltage photogun [Electrostatic design of a triple point junction shield for a -200 kV DC high voltage photogun using COMSOL].  United States: N. p., 2018. 
Web.  doi:10.1063/1.5048700.

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                    Palacios-Serrano, Gabriel G., Hannon, Fay E., Hernandez-Garcia, Carlos, Poelker, Matt, & Baumgart, Helmut. Electrostatic design and conditioning of a triple point junction shield for a –200 kV DC high voltage photogun [Electrostatic design of a triple point junction shield for a -200 kV DC high voltage photogun using COMSOL].  United States.  https://doi.org/10.1063/1.5048700

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                    Palacios-Serrano, Gabriel G., Hannon, Fay E., Hernandez-Garcia, Carlos, Poelker, Matt, and Baumgart, Helmut. Wed .  
"Electrostatic design and conditioning of a triple point junction shield for a –200 kV DC high voltage photogun [Electrostatic design of a triple point junction shield for a -200 kV DC high voltage photogun using COMSOL]".  United States.  https://doi.org/10.1063/1.5048700.  https://www.osti.gov/servlets/purl/1489811.

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@article{osti_1489811,

  title        = {Electrostatic design and conditioning of a triple point junction shield for a –200 kV DC high voltage photogun [Electrostatic design of a triple point junction shield for a -200 kV DC high voltage photogun using COMSOL]},

  author       = {Palacios-Serrano, Gabriel G. and Hannon, Fay E. and Hernandez-Garcia, Carlos and Poelker, Matt and Baumgart, Helmut},

  abstractNote = {Nuclear physics experiments performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at the Jefferson Lab require a DC high voltage photogun to generate polarized electron beams from GaAs photocathodes. The photogun uses a tapered ceramic insulator that extends into the vacuum chamber and mechanically holds the cathode electrode. Increasing the operating voltage from nominal –130 kV to –200 kV will provide lower beam emittance, better transmission through injector apertures, and improved photocathode lifetime. This desire to increase the photogun operating voltage led to the design of a triple-point-junction shield electrode which minimizes the electric field at the delicate insulator-metal-vacuum interface and linearizes the potential across the insulator, thus reducing the risk of arcing along the ceramic insulator. Furthermore, this work describes the results obtained using COMSOL® electrostatic-field simulation software and presents the high voltage conditioning results of the upgraded –200 kV CEBAF photogun.},

  doi          = {10.1063/1.5048700},

  journal      = {Review of Scientific Instruments},

  number       = 10,

  volume       = 89,

  place        = {United States},

  year         = {Wed Oct 03 00:00:00 EDT 2018},

  month        = {Wed Oct 03 00:00:00 EDT 2018}

}

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Journal Article:

Free Publicly Available Full Text

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https://doi.org/10.1063/1.5048700

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Cited by: 6 works

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Figures / Tables:

Figure 1: (left) Current CEBAF photogun with un-doped ceramic insulator, (right) updated photogun with doped ceramic insulator and triple-point-junction shield. Vacuum chamber with (a) anode structure, (b₁,b₂) tapered ceramic insulators with (c) cathode electrode attached. HV conductor surrounded with (d) vulcanized rubber, (e) grounded non-evaporable getter vacuum pumps.

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Works referenced in this record:

Nonevaporable getter coating chambers for extreme high vacuum
journal, May 2018

Stutzman, Marcy L.; Adderley, Philip A.; Mamun, Md Abdullah A.
Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, Vol. 36, Issue 3
DOI: 10.1116/1.5010154

Lifetime measurements of high polarization strained-superlattice gallium arsenide at beam current >1 milliamp using a new 100kv load lock photogun
conference, June 2007

Grames, J.; Adderley, P.; Brittian, J.
2007 IEEE Particle Accelerator Conference (PAC)
DOI: 10.1109/PAC.2007.4440691

Improving the performance of stainless-steel DC high voltage photoelectron gun cathode electrodes via gas conditioning with helium or krypton
journal, October 2014

BastaniNejad, M.; Elmustafa, A. A.; Forman, E.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 762
DOI: 10.1016/j.nima.2014.05.114

Surface flashover of insulators
journal, January 1989

Miller, H. C.
IEEE Transactions on Electrical Insulation, Vol. 24, Issue 5
DOI: 10.1109/14.42158

The Effect of Doping on the Voltage Holdoff Performance of Alumina Insulators in Vacuum
journal, June 1985

Miller, H. Craig
IEEE Transactions on Electrical Insulation, Vol. EI-20, Issue 3
DOI: 10.1109/tei.1985.348774

Figures / Tables found in this record:

Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.

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Similar Records

Title: Electrostatic design and conditioning of a triple point junction shield for a –200 kV DC high voltage photogun [Electrostatic design of a triple point junction shield for a -200 kV DC high voltage photogun using COMSOL]

Abstract

Citation Formats

Figures / Tables:

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Lifetime measurements of high polarization strained-superlattice gallium arsenide at beam current >1 milliamp using a new 100kv load lock photogun
conference, June 2007

Improving the performance of stainless-steel DC high voltage photoelectron gun cathode electrodes via gas conditioning with helium or krypton
journal, October 2014

Surface flashover of insulators
journal, January 1989

The Effect of Doping on the Voltage Holdoff Performance of Alumina Insulators in Vacuum
journal, June 1985