Lower hybrid heating associated with mode conversion on the Wisconsin octupole

Ion heating is measured over a wide range of plasma parameters for sufficiently high values of density and magnetic field corresponding to the appearance of the hot-plasma lower-hybrid-mode conversion layer in the toroidal octupole. At power levels of 20kW at 140MHz ion temperature profile measurements indicate that the heating zone follows the wave turning point as the peak density is varied from n=3x1011cm-3 to n=8x1011cm-3. Results are explained by invoking an upshift in the ksub(parallel) wave power spectrum. (author)