Author: Bazarov, I.V.
Paper Title Page
TUOBS2 Cornell ERL Research and Development 729
 
  • C.E. Mayes, I.V. Bazarov, S.A. Belomestnykh, D.H. Bilderback, M.G. Billing, J.D. Brock, E.P. Chojnacki, J.A. Crittenden, L. Cultrera, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, E. Fontes, C.M. Gulliford, D.L. Hartill, G.H. Hoffstaetter, V.O. Kostroun, F.A. Laham, Y. Li, M. Liepe, X. Liu, F. Löhl, A. Meseck, A.A. Mikhailichenko, H. Padamsee, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, V.D. Shemelin, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, Y. Xie
    CLASSE, Ithaca, New York, USA
  • S.S. Karkare, J.M. Maxson
    Cornell University, Ithaca, New York, USA
 
  Funding: Supported by NSF award DMR-0807731.
Energy Recovery Linacs (ERLs) are proposed as drivers for hard X-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. The advantages of ERL lightsources will be explained, and the status of plans for such facilities will be described. In particular, Cornell University plans to build an ERL light source, and the preparatory research for its construction will be discussed. This will include the prototype injector for high current CW ultra-low emittance beams, superconducting CW technology, the transport of low emittance beams, halo formation from intrabeam scattering, the mitigation of ion effects, the suppression of instabilities, and front to end simulations. Several of these topics could become important for other modern light source projects, such as SASE FELs, HGHG FELs, and XFELOs.
 
slides icon Slides TUOBS2 [5.632 MB]  
 
WEP244 Growth and Characterization of Bialkali Photocathodes for Cornell ERL Injector 1942
 
  • L. Cultrera, I.V. Bazarov, J.V. Conway, B.M. Dunham, Y. Li, X. Liu, K.W. Smolenski
    CLASSE, Ithaca, New York, USA
  • S.S. Karkare, J.M. Maxson
    Cornell University, Ithaca, New York, USA
 
  The requirements of high quantum efficiency in the visible spectral range and that of an increased lifetime as compared to cesiated GaAs can be met by multi-alkali photocathodes, either CsKSb or NaKSb. In this paper we detail the procedures that allow the growth of thin films suitable for the ERL photoinjector operating at Cornell University. Quantum efficiency, spectral response, and surface characterization of deposited samples is presented. A load-locked multi-alkali cathode growth system is also described.  
 
WEP245 Optimization of DC Photogun Electrode Geometry 1945
 
  • J.M. Maxson
    Cornell University, Ithaca, New York, USA
  • I.V. Bazarov, B.M. Dunham, K.W. Smolenski
    CLASSE, Ithaca, New York, USA
 
  DC photoguns that employ electrostatic focusing to obtain lower beam emittance must inherently trade off between focusing strength and the field at the photocathode, and are traditionally pushed to the limits of breakdown voltage. In this paper, we numerically investigate a highly parametrized electrostatic geometry exploring the trade-off between the voltage breakdown condition and electrostatic focusing. We then compare the results to DC gun designs where the focusing is introduced via embedded solenoidal fields. Finally, we present investigations for a multi-anode gun design that seeks to simultaneously achieve both high electric field at the photocathode and high gun voltage without violating the empirical voltage breakdown condition. In the most feasible cases, the electrode geometry is optimized via genetic algorithms. Designs on the optimal front are compared with the current performance of the Cornell ERL prototype DC photogun.  
 
THP192 Effect of Surface Roughness on the Emittance from GaAs Photocathode 2480
 
  • S.S. Karkare, I.V. Bazarov
    Cornell University, Ithaca, New York, USA
  • L. Cultrera, A. Iyer, X. Liu, W.J. Schaff
    CLASSE, Ithaca, New York, USA
 
  Funding: This work is supported by NSF under Grant No. DMR- 0807731 and DOE under Grant No. DE-SC0003965.
The surface roughness of GaAs photocathodes used in the injector prototype for the ERL at Cornell University was measured and compared to that of the atomically polished GaAs crystal surface using the atomic force microscopy (AFM) technique. The results show at least an order of magnitude rise in the GaAs surface roughness after subjecting it to heat cleaning, prior to activation. An analytical model for photoemission that takes into account the effect of surface roughness has been developed. This model predicts emittance values close to the experimental observations, explains the experimentally observed variation of emittance with incident light wavelength and reconciles the discrepancies in experimental data.