Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun

Grames, J M; Adderley, P A; Brittian, J; Clark, J; Hansknecht, J; Machie, D; Poelker, M; Stutzman, M L; Suleiman, R; L Surles-Law, K E

Title: Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun

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Abstract

A new 100 kV GaAs DC Load Lock Photogun has been constructed at Jefferson Laboratory, with improvements for photocathode preparation and for operation in a high voltage, ultra-high vacuum environment. Although difficult to gauge directly, we believe that the new gun design has better vacuum conditions compared to the previous gun design, as evidenced by longer photocathode lifetime, that is, the amount of charge extracted before the quantum efficiency of the photocathode drops by 1/e of the initial value via the ion back-bombardment mechanism. Photocathode lifetime measurements at DC beam intensity of up to 10 mA have been performed to benchmark operation of the new gun and for fundamental studies of the use of GaAs photocathodes at high average current*. These measurements demonstrate photocathode lifetime longer than one million Coulombs per square centimeter at a beam intensity higher than 1 mA. The photogun has been reconfigured with a high polarization strained superlattice photocathode (GaAs/GaAsP) and a mode-locked Ti:Sapphire laser operating near band-gap. Photocathode lifetime measurements at beam intensity greater than 1 mA are measured and presented for comparison.

Authors:: Grames, J M; Adderley, P A; Brittian, J; Clark, J; Hansknecht, J; Machie, D; Poelker, M; Stutzman, M L; Suleiman, R; L Surles-Law, K E

Publication Date:: Wed Aug 01 00:00:00 EDT 2007

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

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 921646

Report Number(s):: JLAB-ACC-07-697; DOE/OR/23177-0257
TRN: US0801657

DOE Contract Number:: AC05-06OR23177

Resource Type:: Conference

Resource Relation:: Conference: 2007 IEEE Particle Accelerator Conference, Albuquerque, NM, 25-30 June 2007

Country of Publication:: United States

Language:: English

Subject:: 43 PARTICLE ACCELERATORS; ACCELERATORS; BEAM CURRENTS; BENCHMARKS; CEBAF ACCELERATOR; DESIGN; GALLIUM ARSENIDES; LASERS; LIFETIME; PHOTOCATHODES; POLARIZATION; QUANTUM EFFICIENCY; SUPERLATTICES

Citation Formats


                    Grames, J M, Adderley, P A, Brittian, J, Clark, J, Hansknecht, J, Machie, D, Poelker, M, Stutzman, M L, Suleiman, R, and L Surles-Law, K E. Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun.  United States: N. p., 2007. 
        Web.

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                    Grames, J M, Adderley, P A, Brittian, J, Clark, J, Hansknecht, J, Machie, D, Poelker, M, Stutzman, M L, Suleiman, R, & L Surles-Law, K E. Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun.  United States.

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                    Grames, J M, Adderley, P A, Brittian, J, Clark, J, Hansknecht, J, Machie, D, Poelker, M, Stutzman, M L, Suleiman, R, and L Surles-Law, K E. 2007.  
        "Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun".  United States.  https://www.osti.gov/servlets/purl/921646.

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@article{osti_921646,

  title        = {Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun},

  author       = {Grames, J M and Adderley, P A and Brittian, J and Clark, J and Hansknecht, J and Machie, D and Poelker, M and Stutzman, M L and Suleiman, R and L Surles-Law, K E},

  abstractNote = {A new 100 kV GaAs DC Load Lock Photogun has been constructed at Jefferson Laboratory, with improvements for photocathode preparation and for operation in a high voltage, ultra-high vacuum environment. Although difficult to gauge directly, we believe that the new gun design has better vacuum conditions compared to the previous gun design, as evidenced by longer photocathode lifetime, that is, the amount of charge extracted before the quantum efficiency of the photocathode drops by 1/e of the initial value via the ion back-bombardment mechanism. Photocathode lifetime measurements at DC beam intensity of up to 10 mA have been performed to benchmark operation of the new gun and for fundamental studies of the use of GaAs photocathodes at high average current*. These measurements demonstrate photocathode lifetime longer than one million Coulombs per square centimeter at a beam intensity higher than 1 mA. The photogun has been reconfigured with a high polarization strained superlattice photocathode (GaAs/GaAsP) and a mode-locked Ti:Sapphire laser operating near band-gap. Photocathode lifetime measurements at beam intensity greater than 1 mA are measured and presented for comparison.},

  doi          = {},

  url          = {https://www.osti.gov/biblio/921646},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {Wed Aug 01 00:00:00 EDT 2007},

  month        = {Wed Aug 01 00:00:00 EDT 2007}

}

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