IMPROVING REGULAR ACCELERATION IN THE NONLINEAR-INTERACTION OF PARTICLES AND WAVES

In this work one studies the effects arising from the inclusion of a stationary extraordinary mode in the resonant interaction of magnetized particles and perpendicularly propagating electrostatic waves. It is found that for a stationary mode frequency of the order of the Larmor frequency and with a suitably chosen amplitude, one is able to suppress the resonance which drives the weakly relativistic dynamics into chaos. Improved regular acceleration of initially low energy particles is thus attained. Analytical estimates of the optimal stationary mode amplitude is presented. A detailed study of the topological effects due to resonance suppression based on bifurcation analysis is performed. The main results are verified with the help of single particle numerical simulations. (C) 1995 American Institute of Physics.