Experimental investigation of the interaction between an electromagnetic field and plasma layer

The effect of nonlinear transparency of a plasma layer in the field of an intense electromagnetic wave is investigated experimentally. Increase of transparency of the plasma is found to involve anisotropic changes in the distribution function as a consequence of which the majority of fast particles move in a direction parallel to the projection of the wave field on the surface of the plasma layer. The bleaching process is nonstationary. The results are interpreted. It is shown that the main characteristics of the effect can be satisfactorily explained by invoking modulation instability in the plasma which leads to excitation of nonlinear Langmuir waves