Author: Padmore, H.A.
Paper Title Page
MOPRI018 Influence of Growth Method on K3Sb Photocathode Structure and Performance 624
 
  • S.G. Schubert, T. Kamps, M. Schmeißer
    HZB, Berlin, Germany
  • K. Attenkofer, J. Smedley
    BNL, Upton, Long Island, New York, USA
  • E.M. Muller
    SBU, Stony Brook, New York, USA
  • H.A. Padmore, J.J. Wong
    LBNL, Berkeley, California, USA
  • M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
  • J. Xie
    ANL, Argonne, Illinois, USA
  
  Funding: Supported by Director, OoS., OBES of US DOE, Contract DE-AC02-05CH11231, DE-AC02-98CH10886, KC0407-ALSJNTI0013, DE-SC0005713, germ. BMBF, Land Berlin, Helmholtz Assoc.. Use of CHESS by NSF, DMR-0936384.
Future high brightness photoelectron sources delivering >100 mA average current call for a new generation of photocathodes. Materials which qualify for this purpose should exhibit low intrinsic emittance, long lifetime and high quantum efficiency at photon energies in the visible range of the spectrum to relax drive laser requirements. A combination of material science techniques are used to determine the influence of the growth parameters on structure and performance of photocathode materials . In-situ XRR, XRD and GiSAXS measurements were performed at the synchrotron radiation sources, NSLS and CHESS. The growth of K3Sb, a precursor material of one of the prime candidates CsK2Sb, was studied intensively to optimize this intermediate growth step in terms of quantum efficiency and roughness. Three methods, a “layer by layer” type and a “super-lattice type” were examined. K3Sb exists in two crystallographic phases, namely cubic and hexagonal. The cubic phase exhibits a higher quantum efficiency at 532 nm than the hexagonal phase and transforms more easily into CsK2Sb, tuning this phase is believed to be one of the key parameters in the CsK2Sb growth. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI018  
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MOPRI063 Alkali Antimonide Photocathodes in a Can 745
 
  • J. Smedley, K. Attenkofer, T. Rao, S.G. Schubert
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
  • J. DeFazio
    PHOTONIS USA Pennsylvanis, Inc., Lancaster, Pennsylvania, USA
  • H.A. Padmore, J.J. Wong
    LBNL, Berkeley, California, USA
  • J. Xie
    ANL, Argonne, Illinois, USA
  
  Funding: Work was supported by the US DOE, under Contracts DE-AC02-05CH11231, DE-AC02-98CH10886, KC0407-ALSJNT-I0013, DE-FG02-12ER41837 and DE-SC0005713. Use of CHESS is supported by NSF award DMR-0936384.
The next generation of x-ray light sources will need reliable, high quantum efficiency photocathodes. These cathodes will likely be from the alkali antimonide family, which currently holds the record for highest average current achieved from a photoinjector. In this work, we explore a new option for delivering these cathodes to a machine which requires them: use of sealed commercial vacuum tubes. Several sealed tubes have been introduced into a vacuum system and separated from their housing, exposing the active photocathode on a transport arm suitable for insertion into a photoinjector. The separation has been achieved without loss of QE. These cathodes are compared to those grown via traditional methods, both in terms of QE and in terms of crystalline structure, and found to be similar. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI063  
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