Extraction of a helium ion beam from an optically polarized helium source gas

[摘要] Optical pumping techniques can be used to produce nuclear polarization in He3 gas excited by a weak electric discharge. By optically polarizing He3 to a polarization P0 and extracting ions from the gas, the resulting ion beam is expected to retain a polarization between P0 and P0 /2 depending on the experimental conditions. Such a polarized beam would have great utility in nuclear physics. An ion source using this principle has been built by straight-forward modifications of normal rf ion-source geometry to provide the higher pressure and lower flow rate needed for the optical pumping. The dependences of ion current upon source gas pressure and cleanli-ness, electrical discharge intensity, the axial magnetic field, and the extraction voltage are measured. He4 rather than He3 has been used to date and ion-beam polarization cannot be measured with the present apparatus. However, under discharge and flow conditions which appear suitable for He3 polarization, beam current of 1 /ua are attained. Methods for measuring beam polarization are proposed. Some future experiments in atomic physics are considered.

[发布机构] Rice University