Hyper-Polarized Deuterium Molecules: An Option to Produce and Store Polarized Fuel for Nuclear Fusion?

Abstract

The use of nuclear-polarized particles is an interesting option to increase the energy output of future fusion reactors or to decrease their costs. However, before polarized particles can be used as polarized fuel studies on production and handling of sufficient amounts of polarized fuels are necessary. This should not be a problem $\mathrm{for}\ {}{^3}\mathrm{He}$ and T, because both can be polarized by so called “optical-pumping”. Unfortunately, this method has not been very successful in producing polarized deuterium yet. For the use of polarized fuel in magnetic-confinement fusion devices (e.g. in tokamaks) the production of polarized deuterium molecules by recombination of polarized deuterium atoms from a polarized atomic beam source is another option. In first experiments with hydrogen, the initial nuclear polarization of about 0.9 has mostly been preserved during the recombination process on a Fomblin surface. For deuterium polarization losses due to wall collisions are expected to be substantially reduced when the temperature of the deuterium gas is lowered to near liquefaction temperatures. Therefore, storing of polarized deuterium molecules seems to be possible, either as very cold gas in strong magnetic fields, or by freezing out as polarized deuterium ice.