Radiative behaviour of a shock-heated argon plasma flow

Experimental and theoretical studies were made of the decrease in the degree of ionization of shock-heated agron resulting from radiative emission. the studies were based on measurment of the time history of the electron density by means of optical interferometry used in conjunction with a rotating mirror camera. These measurments apply to the quasi-euilibrium region which follows the short electronic relaxation zone behind strong shocks. Loss of energy by rediation led to cooling of the gas as evidenced by the decreasing electron density. The analytical studies were based on the assumption that the dense plasma readiated throught both continuu, emission and emission from spectral lines. Comparison was made with experimental results, and theory and experiment were in good agreement, for a realistic choice of the parameters contained in the continuum theory. The analysis indicated that line radiation losses could not be disregarded. Sizeable loss resulted from lower level bound-bound transitions even though these lines experienced absorption.