Absorption of laser radiation in a H-He plasma. II. Experimental measurement of the absorption coefficient

The absorption coefficients of 0.633-, 1.15-, and 3.39-μm laser radiation for a homogeneous H-He plasma have been measured in the temperature range of 12.2 to 21.7 (× 103 °K) and in the electron number density range 0.45 to 6.5 (× 1017 cm−3). Good agreement is found between the experimentally determined total absorption for each of the wavelengths and that calculated from theory. Furthermore, because the 3.39-μm absorption is dominated by inverse bremsstrahlung while the 0.633-μm absorption is dominated by photoionization and resonance absorption, the experiment indicates a correct assessment by the theory of these individual absorption mechanisms.