SPECTROSCOPIC INVESTIGATION OF PLASMA TURBULENCE

Optical studies of plasma fluctuations have been carried out in a toroidal, high-voltage discharge. Following the formation of the helium plasma of density 10**1**9-10**2**0m** minus **3 by rf preionization and a preheating field, the electric field ( less than equivalent to 8kV/m) of the main discharge is applied parallel to the steady toroidal magnetic field of 0. 3 T. Forbidden lines and satellites show that low and high frequency fluctuations are present at early times. An analysis is given of the possible role of these fluctuations in the rapid thermal transport previously observed from the current skin layer to the interior of the plasma. Direct energy transport by propagating electron plasma or ion acoustic waves is shown to be insignificant. However, the low frequency field strength is sufficient to allow for an explanation in terms of enhanced thermal diffusion due to lower hybrid waves.