Influence of the shock-front structure on the nature of luminescence from a recombining laser plasma

Spatial, temporal, and spectral measurements were made of the radiation characteristics of a laser plasma interacting with a plane screen. The angular distribution of the fastest plasma component was constructed, the displacement velocity of the bulk of the plasma was found, the velocity of "reflection" of the shock wave from the screen was determined, and the propagation velocity of a "tongue" of electron heating by heat conduction was estimated. The intensity of the continuous spectrum increased somewhat in the conduction heating zone, where there was a fall in the recombination pumping rate (and consequently in the luminescence of the ion lines). A sharp increase in the intensity of the laser plasma recombination luminescence was recorded when a plane screen was placed in the path of its expansion, and this was shown to be due to the structure of the shock front formed in the plasma. An intensification of the recombination filling of the levels in the shock-wave density discontinuity could be used to amplify radiation due to transitions in multiply charged ions.