Light-Emission Measurements of Sodium at Simulated Meteor Conditions

By use of a crossed-beam technique, the emission cross-sections for the D-lines of sodium have been measured for collisions involving Ar, Ar+, He, He+, 02,02+, 0+, N2, N2+, and N+ with energies from 150 to 2000 eV, corresponding to velocities between 32 and 117 km sec ' for N2. The measured cross-sections were found to be of the order of 10-15 cm2 and to decrease with decreasing energy. Cross-sections for the interactions involving ions were greater by a factor of about 3 than those involving neutrals; however, there were only small differences in the cross-sections due to the species involved in the collision with the sodium. From the emission cross-sections of sodium in collisions with Os and N2, the luminous effi ciency of sodium in air was determined over the range of meteor velocities and found to exceed 1 percent.