PARTICLE DYNAMICS IN CHIRPED-FREQUENCY FLUCTUATIONS

Hamiltonian systems describing particle motion in a wave with time-dep endent (chirped) frequency are studied. The wave is found to form a si ngle-node separatrix (bucket) moving in the phase space at a rate prop ortional to that of the frequency change. Particles trapped inside the bucket undergo convection, while untrapped particles colliding with t he bucket get a resonant kick, in phase space. In toroidal systems, th ese effects can result in a large radial convective flux roughly propo rtional to the size of the bucket and the frequency chirping. Possible applications of this novel mechanism to tokamak plasmas are discussed .