CHEMOIONIZATION AND SPIN-EXCHANGE IN COLLISIONS OF EXCITED METASTABLEHELIUM-ATOMS WITH SODIUM ATOMS IN THE GROUND-STATE - I - KINETICS OF OPTICAL ORIENTATION

The kinetics of optical orientation in a He-Na gas-discharge plasma is considered and the polarization redistribution caused by both the col lisional processes (elastic and inelastic) and the hyperfine interacti on in the Na atom in the ground state is analyzed. The evolution equat ions for the quantities observed in the experiment (orientation and al ignment) are derived. The situation in which the spin exchange and the chemoionization simultaneously take place in the system is analyzed f or the first time. Relations between the linewidrhs of magnetic resona nce of oriented and aligned atoms and the cross sections for spin exch ange and chemoionization are obtained.