Dunning, F. B.2009-06-032009-06-031989Rutherford, George Henry. "An intense source of spin-polarized electrons based on an optically-pumped flowing helium afterglow." (1989) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/13388">https://hdl.handle.net/1911/13388</a>.https://hdl.handle.net/1911/13388The optimization of an optically-pumped, flowing helium afterglow for use as a high-current dc polarized electron source with high electron spin polarization is described. The atomic electron spins of He (2$\sp3\rm S\sb1$) metastable atoms created by a microwave discharge are aligned in the presence of a weak magnetic field by circularly polarized radiation from a recently developed LNA laser. The polarized outer 2s electrons are liberated in spin-conserving Penning ionization reactions with CO$\sb2$ and are extracted from the flow tube for polarization analysis. Polarizations approaching 90% were obtained at currents below.1 $\mu$A, falling gradually to 70% at 20 $\mu$A. Comparisons with other sources, chiefly photoemission from GaAs, suggest that for most applications requiring dc currents less than 50 $\mu$A, the flowing afterglow source is superior. Possible future improvements to the present source are also discussed.54 p.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Atomic physicsThesisThesis Phys. 1989 Rutherford