Polarized He-3 gas compression system using metastability-exchange optical pumping

Abstract

Dense samples (10-100 bar cm) of nuclear spin polarized He-3 are utilized in high energy physics, neutron scattering, atomic physics, and magnetic resonance imaging. Metastability exchange optical pumping can rapidly produce high He-3 polarizations (≈ 80%) at low pressures (few mbar). We describe a polarized He-3 gas compressor system which accepts 0.26 bar l h(-1) of He-3 gas polarized to 70% by a 4 W neodymium doped lanthanum magnesium hexaluminate (Nd:LMA) laser and compresses it into a 5 bar cm target with final polarization of 55%. The spin relaxation rates of the system\u27s components have been measured using nuclear magnetic resonance and a model of the He-3 polarization loss based on the measured relaxation rates and the gas flow is in agreement with a He-3 polarization measurement using neutron transmission. © 2005 American Institute of Physics