WAVE-INDUCED CHAOTIC RADIAL TRANSPORT OF ENERGETIC ELECTRONS IN A LABORATORY TERRELLA EXPERIMENT

This paper reports the observation of wave-induced chaotic radial tran sport of energetic electrons in a laboratory terrella, the Collisionle ss Terrella Experiment (CTX) [H. P. Warren and M. E. Mauel, Phys. Rev. Lett. 74, 1351 (1995)]. Electron cyclotron resonance heating is used to create a localized population of energetic electrons which excite t he hot electron interchange instability. The electrostatic fluctuation s driven by this instability have time-evolving spectra which resonate with the precessional drift motion of the hot electrons. We have esta blished that the amplitude, frequency, and azimuthal mode number of th e observed instabilities meet the conditions for the onset of chaotic particle motion. Electron transport is observed with a gridded particl e detector. Increases in the flux of energetic particles to the detect or are well correlated with the presence of fluctuations which meet th e conditions for global chaos. Greatly diminished transport is observe d when the fluctuations lead to thin, radially localized bands of chao s. The flux of energetic electrons to the detector is strongly modulat ed. By examining time-dependent Hamiltonian phase space flows, the mod ulation is shown to be the result of phase space correlations. A trans port simulation based on the Hamiltonian motion of energetic electrons reproduces the frequency and modulation depth of the observed electro n flux and allows for comparison between the Hamiltonian and quasiline ar descriptions of transport. (C) 1995 American Institute of Physics.