UC Irvine

Positive/negative ion plasmas, composed of Ba+, SF 6-, and residual electrons, were observed to display characteristics of strong turbulence. Experiments on the UCI Q machine linked the presence of negative ions (and the depletion of electrons) with large density fluctuations (δn/ n≃1), large-amplitude, low-frequency electrostatic noise (f≤20 kHz), and rapid transport of ions across magnetic field lines (DL⊥≃104 cm2/sec). Ion velocity distributions were heated parallel to and cooled perpendicular to the confining magnetic field. The partial pressure of gaseous SF6 was shown to serve as a regulator of plasma turbulence. Turbulence levels could be smoothly varied from quiescent states (δn/n≃0.01) to strongly turbulent states (δn/n≃=0.01). © 1993 American Institute of Physics.