Diffusive transfer of polarized 3He gas through depolarizing magnetic gradients

Abstract

Transfer of polarized 3 He gas across spatially varying magnetic fields will facilitate a new source of polarized 3 He ions for particle accelerators. In this context, depolarization of atoms as they pass through regions of significant transverse field gradients is a major concern. To understand these depolarization effects, we have built a system consisting of a Helmholtz coil pair and a solenoid, both with central magnetic fields of order 30 gauss. The atoms are polarized via metastability exchange optical pumping in the Helmholtz coil and are in diffusive contact via a glass tube with a second test cell in the solenoid. We have carried out measurements of the spin relaxation during transfer of polarization in 3 He at 1 torr by diffusion. We explore the use of measurements of the loss of polarization taken in one cell to infer the polarization in the other cell.

Development of a Polarized Helium-3 Source for RHIC and eRHIC

“…A MEOP polarizer has been built at MIT to undertake initial investigations, including the measurement of polarized 3 He via RF discharge light 7 and the observation of diffusion of polarized gas through depolarizing gradients. 8 A probe laser polarimeter has also been developed to allow polarization measures at low or high magnetic fields, a technique pioneered at the Kastler-Brossel Laboratory in Paris. 9 In the summer of 2014, a second polarizing apparatus was assembled at BNL to perform tests to assess the viability of two options for the final source design: low field or high field MEOP.…”

Optically polarizedHe3

“…This analysis provided a theoretical justification for the usual assumption that the relaxation rate is determined by the volume average of the relevant gradients. Studies of gradient-induced relaxation in the transfer of gas into high magnetic fields has been also been reported (Maxwell et al , 2015; Zheng et al , 2011a). …”

Polarized He3 Ion Source for RHIC and eRHIC

“…A MEOP polarizer was built at MIT to undertake initial investigations at low field, including the measurement of polarized 3 He via RF discharge light [7] and the observation of diffusion of polarized gas through depolarizing gradients [8]. A second pumping setup at BNL has allowed tests in the stray field of the spare EBIS 5 T solenoid.…”