Trapping of low-density ambient gas by a laser plasma

Probe experiments showed that the total ionic charge of a laser plasma expanding in a partly ionized low-density gas under interpenetration conditions had a maximum at a specific gas pressure inside the chamber. Mass-spectrometric investigations confirmed the results of these probe measurements. The laser target was a flat sheet of aluminum and the low-density (ambient) gas was air and xenon. It was demonstrated that ion–ion collisions made a considerable contribution to plasma heating.