INSTABILITIES OF SHORT-PULSE LASER PROPAGATION THROUGH PLASMA CHANNELS

The stability of short laser pulses propagating through plasma channels is investigated theoretically. Perturbations to the laser pulse are shown to modify the ponderomotive pressure, which distorts the dielectric properties of the plasma channel. The channel perturbation then further distorts the laser pulse. A set of coupled mode equations is derived, and a matrix dispersion relation is obtained analytically for the special case of a quadratic radial density variation. As an example, the spatiotemporal growth of a pure dipole perturbation is evaluated in various parameter regimes. Mechanisms for suppressing the instability are discussed. © 1994 The American Physical Society.