  We describe a method to hyperpolarize 3He nuclear spins at high magnetic
fields (4.7 Tesla) solely by a magnetized plasma. The conditions for such a
magnetized plasma are fulfilled when the mean free path of the free electrons
is much larger than their gyration radius in the rf gas discharge.
Investigations are carried out in the 1-15 mbar pressure range with rf
excitation at ~100 MHz. Quantitative NMR measurements show that for different
cell sizes and 3He densities nuclear polarizations in the range 1% to 9% are
observed. We explain this phenomenon by an alignment-to-orientation conversion
mechanism in the excited 2 3P state of 3He which is most efficient when the
Zeeman and the spin-orbit energies are comparable. The method appears as a very
attractive alternative to established laser polarization techniques (spin
exchange or metastability exchange optical pumping). Application to 3He nuclear
magnetometry with a relative precision of 10-12 is demonstrated.
