Spectral change mechanism in the pulsed high-pressure sodium arc

Abstract

The enhancement of radiative output of the pulsed high-pressure sodium discharge in the blue region of the visible spectrum is due principally to radiation from the nd2D→3p2P transitions of the sodium atom where n=4–15. Excitation of these upper energy levels results from a transient non-steady-state increase in plasma temperature to about 5500 °K in the center of the arc. This temperature decays to a value near that encountered in steady-state excitation conditions in a time comparable to the empirically optimized pulse duration and to the previously determined time for plasma temperature relaxation.