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Experimental studies of the charge limit phenomenon in NEA GaAs photocathodes

Conference ·
OSTI ID:10194017
Negative electron affinity GaAs photocathodes have been in continuous use at SLAC for generating polarized electron beams since early 1992. If the quantum efficiency of a GaAs cathode is below a critical value, the maximum photoemitted charge with photons of energies close to the band gap in a 2-ns pulse is found to be limited by the intrinsic properties of the cathode instead of by the space charge limit. We have studied this novel charge limit phenomenon in a variety of GaAs photocathodes of different structures and doping densities. We find that the charge limit is strongly dependent on the cathode`s quantum efficiency and the extraction electric field, and to a lesser degree on the excitation laser wavelength. In addition, we show that the temporal behavior of the charge limit depends critically on the doping density.
Research Organization:
Stanford Linear Accelerator Center, Menlo Park, CA (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
AC03-76SF00515
OSTI ID:
10194017
Report Number(s):
SLAC-PUB--6515; CONF-940618--89; ON: DE95002866
Country of Publication:
United States
Language:
English

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