Two-photon photoemission from a copper cathode in an X -band photoinjector

Li, H.; Limborg-Deprey, C.; Adolphsen, C.; McCormick, D.; Dunning, M.; Jobe, K.; Raubenheimer, T.; Vrielink, A.; Vecchione, T.; Wang, F.; Weathersby, S.

doi:10.1103/PhysRevAccelBeams.19.023401

Title: Two-photon photoemission from a copper cathode in an $X$ -band photoinjector

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Abstract

This study presents two-photon photoemission from a copper cathode in an X-band photoinjector. We experimentally verified that the electron bunch charge from photoemission out of a copper cathode scales with laser intensity (I) square for 400 nm wavelength photons. We compare this two-photon photoemission process with the single photon process at 266 nm. Despite the high reflectivity (R) of the copper surface for 400 nm photons (R=0.48) and higher thermal energy of photoelectrons (two-photon at 200 nm) compared to 266 nm photoelectrons, the quantum efficiency of the two-photon photoemission process (400 nm) exceeds the single-photon process (266 nm) when the incident laser intensity is above 300 GW/cm². At the same laser pulse energy (E) and other experimental conditions, emitted charge scales inversely with the laser pulse duration. A thermal emittance of 2.7 mm-mrad per mm root mean square (rms) was measured on our cathode which exceeds by sixty percent larger compared to the theoretical predictions, but this discrepancy is similar to previous experimental thermal emittance on copper cathodes with 266 nm photons. The damage of the cathode surface of our first-generation X-band gun from both rf breakdowns and laser impacts mostly explains this result. Using a 400 nm laser canmore »« less

Authors:: Li, H.; Limborg-Deprey, C.; Adolphsen, C.; McCormick, D.; Dunning, M.; Jobe, K.; Raubenheimer, T.; Vrielink, A.; Vecchione, T.; Wang, F.; Weathersby, S.

Publication Date:: Wed Feb 24 00:00:00 EST 2016

Research Org.:: SLAC National Accelerator Lab., Menlo Park, CA (United States)

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

OSTI Identifier:: 1239429

Alternate Identifier(s):: OSTI ID: 1239995

Grant/Contract Number:: AC03-76SF00515

Resource Type:: Published Article

Journal Name:: Physical Review Accelerators and Beams

Additional Journal Information:: Journal Volume: 19; Journal Issue: 2; Journal ID: ISSN 2469-9888

Publisher:: American Physical Society

Country of Publication:: United States

Language:: English

Subject:: 43 PARTICLE ACCELERATORS

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                    Li, H., Limborg-Deprey, C., Adolphsen, C., McCormick, D., Dunning, M., Jobe, K., Raubenheimer, T., Vrielink, A., Vecchione, T., Wang, F., and Weathersby, S. Two-photon photoemission from a copper cathode in an X -band photoinjector.  United States: N. p., 2016. 
Web.  doi:10.1103/PhysRevAccelBeams.19.023401.

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                    Li, H., Limborg-Deprey, C., Adolphsen, C., McCormick, D., Dunning, M., Jobe, K., Raubenheimer, T., Vrielink, A., Vecchione, T., Wang, F., & Weathersby, S. Two-photon photoemission from a copper cathode in an X -band photoinjector.  United States.  https://doi.org/10.1103/PhysRevAccelBeams.19.023401

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                    Li, H., Limborg-Deprey, C., Adolphsen, C., McCormick, D., Dunning, M., Jobe, K., Raubenheimer, T., Vrielink, A., Vecchione, T., Wang, F., and Weathersby, S. Wed .  
"Two-photon photoemission from a copper cathode in an X -band photoinjector".  United States.  https://doi.org/10.1103/PhysRevAccelBeams.19.023401.

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@article{osti_1239429,

  title        = {Two-photon photoemission from a copper cathode in an X -band photoinjector},

  author       = {Li, H. and Limborg-Deprey, C. and Adolphsen, C. and McCormick, D. and Dunning, M. and Jobe, K. and Raubenheimer, T. and Vrielink, A. and Vecchione, T. and Wang, F. and Weathersby, S.},

  abstractNote = {This study presents two-photon photoemission from a copper cathode in an X-band photoinjector. We experimentally verified that the electron bunch charge from photoemission out of a copper cathode scales with laser intensity (I) square for 400 nm wavelength photons. We compare this two-photon photoemission process with the single photon process at 266 nm. Despite the high reflectivity (R) of the copper surface for 400 nm photons (R=0.48) and higher thermal energy of photoelectrons (two-photon at 200 nm) compared to 266 nm photoelectrons, the quantum efficiency of the two-photon photoemission process (400 nm) exceeds the single-photon process (266 nm) when the incident laser intensity is above 300 GW/cm2. At the same laser pulse energy (E) and other experimental conditions, emitted charge scales inversely with the laser pulse duration. A thermal emittance of 2.7 mm-mrad per mm root mean square (rms) was measured on our cathode which exceeds by sixty percent larger compared to the theoretical predictions, but this discrepancy is similar to previous experimental thermal emittance on copper cathodes with 266 nm photons. The damage of the cathode surface of our first-generation X-band gun from both rf breakdowns and laser impacts mostly explains this result. Using a 400 nm laser can substantially simplify the photoinjector system, and make it an alternative solution for compact pulsed electron sources.},

  doi          = {10.1103/PhysRevAccelBeams.19.023401},

  journal      = {Physical Review Accelerators and Beams},

  number       = 2,

  volume       = 19,

  place        = {United States},

  year         = {Wed Feb 24 00:00:00 EST 2016},

  month        = {Wed Feb 24 00:00:00 EST 2016}

}

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Title: Two-photon photoemission from a copper cathode in an X -band photoinjector

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Title: Two-photon photoemission from a copper cathode in an $X$ -band photoinjector