Broad-band laser optical pumping of Rb for the creation of nuclear polarisation in 3He

A large volume (30 cm³) of dense (up to 10¹⁵ cm^-3) Rb vapour was pumped optically by a high-power laser diode array. The conditions for the propagation of high-power broad-band optical pump radiation through an optically dense medium were examined. A spectroscopic method was developed for determination of the polarisation of Rb. The dependence of the polarisation of Rb on its vapour pressure was investigated at buffer gas pressures of 1, 8, and 13 bar. Under optimal conditions a 15-W diode laser made it possible to polarise at least 10¹⁸ of ³He atoms per second during collisions between Rb and ³He atoms, sufficient for the creation of an efficient neutron polariser.