Drift-Alfven wave transport studies in the Large Plasma Device

The Large Plasma Device (LAPD) at UCLA is a unique testbed for performing controlled and detailed transport experiments. Tailored density gradients have been created within an effectivly infinite (perpendicular to B$_0$) plasma using biased electrodes. Spontaneous density and potential fluctuations (drift waves) are observed in the steepest density region. These waves are correlated with cross-field particle flux and lead to a relaxation of the density gradient. The process of growth and disruption repeats in a semi-periodic fashion. Since the plasma beta is typically near the electron-to-ion mass ratio, the waves are of the drift-Alfven type and have both density and magnetic fluctuations. The background plasma is pulsed once per second for months at a time which allows for high spatial and temporal resolution measurements of the entire process, and for different background magnetic fields strengths, ion species, gradient scale lengths, and electron temperatures.