Measurement and temporal behaviour analysis of the plasma–glass boundary layer in a T-tube

Refraction of a laser beam by a flat boundary layer between a plasma and a glass plate was measured and the time development of the layer was analysed. Results of the analysis for the plasma produced in a small T-tube show that the boundary layer thickness increases with time faster than linearly. The boundary layer is negligibly thin during the first 3 mus after the reflected shock front has passed the point of observation. This means that a relatively fast collapse due to cooling through the boundary layer occurs in the second part of the reflected plasma lifetime.