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Fliller, R.P.

Paper Title Page
TPAE048 The UCLA/FNPL Time Resolved Underdense Plasma Lens Experiment 3013
 
  • M.C. Thompson, H. Badakov, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • H. Edwards, R.P. Fliller, G.M. Kazakevich, P. Piot, J.K. Santucci
    Fermilab, Batavia, Illinois
  • J.L. Li, R. Tikhoplav
    Rochester University, Rochester, New York
 
  Funding: Work Supported by U.S. Dept. of Energy grant DE-FG03-92ER40693.

An underdense plasma lens experiment is planned as a collaboration between UCLA and the Fermilab NICADD Photoinjector Laboratory (FNPL). The experiment will focus on measuring the variation of the plasma focusing along the longitudinal beam axis and comparing these results with theory and simulation. The experiment will utilize a thin gaussian underdense plasma lens with peak density 6 x 1012 cm-3 and a FWHM length of 1.6 cm. This plasma lens will have a focusing strength equivalent to a quadrupole magnet with a 180 T/m field gradient. A 15 MeV, 8nC electron beam with nominal dimensions sr = 400 μm and sz = 2.1 mm will be focused by this plasma lens onto an OTR screen approximately 2 cm downstream of the lens. The light from the OTR screen will be imaged into a streak camera in order to directly measure the correlation between z and sr within the beam. Status and progress on the experiment are reported.

 
WPAP041 Time Dependent Quantum Efficiency and Dark Current Measurements in an RF Photocathode Injector with a High Quantum Efficiency Cathode 2681
 
  • R.P. Fliller, H. Edwards
    Fermilab, Batavia, Illinois
  • W. Hartung
    NSCL, East Lansing, Michigan
 
  Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE and by NICADD.

A system was developed at INFN Milano for preparing cesium telluride photo-cathodes and transferring them into an RF gun under ultra-high vacuum. This system has been in use at the Fermilab NICADD Photo-Injector Laboratory (FNPL) since 1997. A similar load-lock system is used at the TeSLA Test Facility at DESY-Hamburg. Two 1.625-cell high duty cycle RF guns have been fabricated for the project. Studies of the photo-emission and field emission ("dark current") behavior of both RF guns have been carried out. Unexpected phenomena were observed in one of the RF guns. In situ changes in the cathode's quantum efficiency and dark current with time were seen during operation of the photo-injector. These changes were correlated with the magnetostatic field at the cathode.* In addition, multipacting is observed in the RF guns under certain conditions. Recent measurements indicate a correlation between multipacting, anomalous photo-emission behavior, and anomalous field emission behavior. Results will be presented.

*W. Hartung, J.-P. Carneiro, H. Edwards, M. Fitch, M. Kuchnir, P. Michelato, D. Sertore, in Proceedings of the 2001 Particle Accelerator Conference, p. 2239-2241.

 
WPAP042 Progress on Using NEA Cathodes in an RF Gun 2708
 
  • R.P. Fliller, T. G. Anderson, H. Edwards
    Fermilab, Batavia, Illinois
  • H. Bluem, T. Schultheiss
    AES, Medford, NY
  • M. Huening
    DESY, Hamburg
  • C.K. Sinclair
    Cornell University, Department of Physics, Ithaca, New York
 
  Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE and by NICADD. AES personnel were supported under DOE SBIR contract #DE-FG02-04ER838.

RF guns have proven useful in multiple accelerator applications, and are an attractive electron source for the ILC. Using a NEA GaAs photocathode in such a gun allows for the production of polarized electron beams. However the lifetime of a NEA cathode in this environment is reduced by ion and electron bombardment and residual gas oxidation. We report progress made with studies to produce a RF gun using a NEA GaAs photocathode to produce polarized electron beams. Attempts to reduce the residual gas pressure in the gun are discussed. Initial measurements of ion flux through the cathode port are compared with simulations of ion bombardment. Future directions are also discussed.