CHAOTIC DYNAMICS OF CHARGED-PARTICLES IN THE FIELD OF 2 MONOCHROMATICWAVES IN A MAGNETIZED PLASMA

We study the dynamics of charged particles in the presence of two elec trostatic waves propagating obliquely to an ambient magnetic field. Th e presence of a second wave makes the problem a two-dimensional and ti me-dependent one with a complicated phase space behavior. We derive a set of difference equations (maps) for the nonrelativistic particle mo tion limit and numerically study them to elucidate the various aspects of the phase space dynamics. For the general case of oblique propagat ion, we observe synergistic effects leading to the lowering of the sto chasticity threshold and the concomitant reduction in electric field a mplitudes for particle heating applications. These results can be unde rstood in terms of the resonance structures associated with the two wa ves and we obtain approximate analytic expressions for the thresholds. For the degenerate case of omega(1)=n Omega,omega(2)=m Omega (where o mega(1),omega(2) are the frequencies of the two waves, Omega is the cy clotron frequency and n,m are integers) and strictly perpendicular pro pagation, the problem simplifies to a one-and-one-half-dimensional one . We observe the presence of stochastic webs in this situation. (C) 19 96 American Institute of Physics.