Plasma production in a toroidal heliac by helicon waves

Abstract

rf power in the lower-hybrid-frequency range is shown to produce plasma of density in the ${10}^{13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ range in the small toroidal heliac SHEILA by launching helicon waves. Measurements of wave dispersion and mode structure confirm that an m=1 helicon mode is launched inside the highly asymmetric plasma confined in the device. The suggestion that the main energy-transfer mechanism is by Landau damping is strongly supported by the experimental data.