Author: Rao, T.
Paper Title Page
MOPPP041 Effect of Roughness on Emittance of Potassium Cesium Antimonide Photocathodes 655
  • T. Vecchione, J. Feng, H.A. Padmore, W. Wan
    LBNL, Berkeley, California, USA
  • I. Ben-Zvi, M. Ruiz-Osés, L. Xue
    Stony Brook University, Stony Brook, USA
  • D. Dowell
    SLAC, Menlo Park, California, USA
  • T. Rao, J. Smedley
    BNL, Upton, Long Island, New York, USA
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U. S. Department of Energy, under Contract DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC0005713
Here we present first measurements of the effect of roughness on the emittance of K2CsSb photocathodes under high fields. We show that for very thin cathodes the effect is negligible at up to 3 MV/m but for thicker and more efficient cathodes the effect becomes significant. We discuss ways to modify the deposition to circumvent this problem.
TUPPD082 Simulations of Multipacting in the Cathode Stalk and FPC of 112 MHz Superconducting Electron Gun 1593
  • T. Xin, X. Liang
    Stony Brook University, Stony Brook, USA
  • S.A. Belomestnykh, I. Ben-Zvi, T. Rao, J. Skaritka, E. Wang, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • X. Chang
    Far-Tech, Inc., San Diego, California, USA
  Funding: Work is supported at BNL by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. The work at Stony Brook is supported by the US DOE under grant DE-SC0005713.
A 112 MHz superconducting quarter-wave resonator electron gun will be used as the injector of the Coherent Electron Cooling (CEC) proof-of-principle experiment at BNL. Furthermore, this electron gun can be used for testing of the performance of various high quantum efficiency photocathodes. In a previous paper, we presented the design of the cathode stalks and a Fundamental Power Coupler (FPC). In this paper we present updated designs of the cathode stalk and FPC. Multipacting in the cathode stalk and FPC was simulated using three different codes, Multipac, CST particle studio and FishPact respectively. All simulation results show no serious multipacting in the cathode stalk structure and FPC.
THAP01 Secondary-electron Emission from Hydrogen-terminated Diamond 3223
  • E. Wang, I. Ben-Zvi, T. Rao, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • D.A. Dimitrov
    Tech-X, Boulder, Colorado, USA
  • T. Xin
    Stony Brook University, Stony Brook, USA
  Diamond amplifiers demonstrably are an electron source with the potential to support high-brightness, high-average-current emission into a vacuum. We recently developed a reliable hydrogenation procedure for the diamond amplifier. The systematic study of hydrogenation resulted in the reproducible fabrication of high gain diamond amplifier. Furthermore, we measured the emission probability of diamond amplifier as a function of the external field and modeled the process with resulting changes in the vacuum level due to the Schottky effect. We demonstrated that the decrease in the secondary electrons’ average emission gain was a function of the pulse width and related this to the trapping of electrons by the effective NEA surface. The findings from the model agree well with our experimental measurements. As an application of the model, the energy spread of secondary electrons inside the diamond was estimated from the measured emission.  
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