An intense electromagnetic wave propagating in a collisional plasma is found to be unstable to a thermal self-focusing instability by a self-consistent solution of the hydrodynamic, heat conductivity, and wave propagation equations. The results are applied to ionospheric modifications and proposed power transmission experiments, and to laser-plasma interactions.

• Received 9 November 1973

DOI:https://doi.org/10.1103/PhysRevLett.32.1234