Differential Diffusion of Helium Isotopes in Glass, Quantum-tunneling He Enrichment, and Portable He/He Monitoring of Mantle Processes.

While studying the scientific and engineering aspects of a field-portable He/He ratio detector, we found elevated ratios at comparatively lower temperatures that appear to result from differential diffusion of these isotopes in pure quartz glass. The He enrichment relative to He in lab air, expressed as the ratio R and normalized to the accepted He/He ratio of 1.40 E-06 (R), ranges from peak values of about 200 to 600 in dry static samples.