Ponderomotive effects in collisionless plasma: A Lie transform approach

A new method for the kinetic analysis of ponderomotive effects in collisionless plasma is presented. This method involves the application of the Lie-transform perturbation technique to the Hamiltonian formulation of the Vlasov equation. Basically, a new system, in which the high frequency oscillations are absent, is found. In this system the distribution function evolves according to a ponderomotive Hamiltonian, which is the kinetic generalization of the ponderomotive potential. It is shown that the ponderomotive Hamiltonian can easily be determined from the well-known linear susceptibility. This formalism is used to calculate several new results. Among these results are the general formula for the quasi-static density perturbation produced by a hot magnetoplasma wave, a generalization of previous formulas for the laser-generated quasi-static magnetic field, and the general formula for the ponderomotive gyrofrequency shift produced by an electromagnetic wave propagating at an arbitrary angle.