Theory of the thermal filamentation instability in the collisionless transport limit

The kinetic theory of the stationary and nonstationary thermal filamentation instability in fully ionized plasmas is presented. The collisionless transport limit is modeled by new transport coefficients corresponding to the convective heat flux and the temperature anisotropy. It is shown, in particular, that these effects decrease the instability growth rates by about a factor of 2, in conditions typical of current experiments. These two effects, combined with the collisional absorption of the light energy by the plasma electrons, lead to a thermal growth rate comparable to the one due to the ponderomotive drive. The comparison of the results obtained in this work with the principal results established in the literature, is also presented. (C) 1999 American Institute of Physics. [S1070-664X(99)00509-1].