Optical Pumping of Metastable Helium Atoms in Polarized Electron Sources

(Received 1 June 1994, revised 12 December 1994, accepted 22 December 1994)

Abstract
In this paper we present a comparison between the Orsay and Rice University polarized electron sources. Different explanations of the polarization degradation are discussed for the two cases. For the Rice source radiation, trapping can account for the observed reduction in polarization because of the high absorption cross sections associated with the D ₁ transition. Some improvements are proposed that might increase the electron polarization.