POLARIZATION OF HE-3, D-2 AND (EVENTUALLY) XE-129 USING LOW-TEMPERATURES AND HIGH MAGNETIC-FIELDS

The recent discovery that inhaling polarized He-3 or Xe-129 allows hig h resolution MRI images of the lungs to be made is having a large impa ct among the medical and physics communities. In fact, this technique could become the first high resolution, harmless diagnostic tool for s everal lung diseases. Neutron-lean nuclear fusion would also benefit f rom the use of polarized fuel (D, He-3) through an enhanced fusion cro ss-section. At present, laser techniques are being used for polarizing He-3 and Xe-129, but the yield is still quite low, at most a few tens of liters per day. Cryogenic techniques combining high magnetic field s and lour temperatures could be used to produce much larger quantitie s of highly polarized He-3 through adiabatic compression. In a reasona ble field of 15 T and 5 mK the polarization of the resulting solid is larger than 95%. Once polarized the solid is melted. The magnetization remains in the liquid for several minutes and the cell could be moved to a region at 6-7 K where the liquid would evaporate. The resulting gas could be removed and kept in a convenient vessel. Extraction could in principle be done in a time much shorter than the relaxation time T of the liquid, which has a minimum around 300 s at 1 bar pressure. T his process could produce large quantities of gas in the range of 100 to 1000 l/day. Wie have also demonstrated that by condensing molecular deuterium (catalized to mostly J = 0) inside the He-3 cell it was pos sible to polarize the D-2 molecules to 13%. Production of finely divid ed D-2 should lead to quite larger polarizations. Using this technique one might consider the polarization of Xe-129.