STOCHASTIC ION BEHAVIOR IN SUBHARMONIC AND SUPERHARMONIC ELECTROSTATIC-WAVES

The dynamics of a charged particle in a magnetic held perturbed by ele ctrostatic waves propagating transverse to the magnetic field has been investigated. Depending on the number of perturbing waves, the magnit ude of the perturbation and the perturbation frequency (v=r/s=omega/om ega(0), where r and s are relatively prime integers, and omega(0) is t he cyclotron frequency), the particle motion can exhibit either a smal l deviation from simple cyclotron motion or stochastic motion over pha se space. The latter case is found to correspond to particle heating a nd anomalous transport. In the case of cyclotron harmonic perturbation s (superharmonic case, s=1), the phase space of the particle is covere d by a stochastic web, inside of which the particle motion is chaotic. The particle can, in principle, be heated to very high energy. Howeve r, if the wave frequency is some fraction of the ion cyclotron frequen cy (subharmonic case, s greater than or equal to 2), the heating range is limited. (C) 1996 American Institute of Physics.