Temperature Gradient Effects and Plasma Confinement in a Q-Device

Azimuthal components of the electric field in Q-machine plasmas may occur if the distribution of temperature over the end plates deviates from rotational symmetry. In this case, Eθ×Bz drifts give rise to plasma loss rates which may be comparable in magnitude to Bohm diffusion. This effect is verified experimentally in a double-ended Q machine. A new heater system for the end plates using rotating cathodes yields temperature distributions which are symmetrical within less than 0.1%. Under these conditions the loss rate is reduced by a factor of 10 to 60 as compared to operation with conventional heater systems.