High capacity production of >65% spin polarized xenon-129 for NMR spectroscopy and imaging

A rubidium spin exchange optical pumping system for high capacity production of >65% spin polarized 129Xe gas is described. This system is based on a fiber coupled multiple laser diode array capable of producing an unprecedented 210 W of circularly polarized light at the pumping cell with a laser line width of 1.6 nm. The 129Xe nuclear spin polarization is measured as a function of flow rate, pumping cell pressure, and laser power for varying pumping gas compositions. A maximum 129Xe nuclear polarization of 67% was achieved using a 0.6% Xe mixture at a Xe flow rate of 2.45 sccm. The ability to generate 12% polarized 129Xe at rates in excess of 1 L-atm/h is also demonstrated. To achieve production of 129Xe gas at even higher polarization will rely on further optimization of the pumping cell and laser beam geometries in order to mitigate problems associated with temperature gradients that are encountered at high laser power and Rb density.