Instability of a plasma produced by laser-induced ionisation of a target

The development of a longitudinal - transverse instability in a plasma with the anisotropic velocity distribution of electrons produced by the tunnelling ionisation of a target by a short laser pulse is studied. The dependences of the growth rate of this longitudinal - transverse instability on the wave number and the propagation angle of perturbations are investigated. It is shown that the increasing longitudinal electrostatic field in a rather broad angular region is comparable with the exciting magnetic field. It is pointed out that the longitudinal - transverse instability of the anisotropic plasma can lead to the additional absorption of laser radiation by the nonthermal fluctuations of the electron density.