ION DYNAMICS IN MULTIPLE ELECTROSTATIC-WAVES IN A MAGNETIZED PLASMA -I - COHERENT ACCELERATION

A new phenomenon of coherent acceleration of ions by a discrete spectr um of electrostatic waves propagating perpendicularly to a uniform mag netic field is described. It allows the energization of ions whose ini tial energies correspond to a region of phase space that is below the chaotic domain. The ion orbits below the chaotic domain are described very accurately using a perturbation analysis to second order in the w ave amplitudes. This analysis shows that the coherent acceleration tak es place only when the wave spectrum contains at least two waves whose frequencies are separated by an amount close to an integer multiple o f the cyclotron frequency. The way the ion energization depends on the wave numbers and wave amplitudes is also presented in detail using th e results of the perturbation analysis. (C) 1998 American Institute of Physics. [S1070-664X(98)02509-9].