Anomalous Absorption of Very High-Intensity Laser Pulses Propagating through Moderately Dense Plasma

The results of a systematic study of the propagation of very high-intensity laser pulses through slabs of plasma of several tens of microns are presented. One-dimensional and two-dimensional electron parametric instabilities are evidenced. They lead to a rapid longitudinal and transverse heating, and to filamentary structures which progressively merge. The heating results in highly energetic electrons with energy of several tens of MeV. Correlatively, a strong attenuation rate of the electromagnetic wave is observed. {copyright} {ital 1997} {ital The American Physical Society}