Plasma heating and current drive by Alfven waves

The results of experimental studies on plasma heating, stationary current drive and impurity transport phenomena with Alfven waves excited in the R-O5 tokamak and the R-O stellarator are given. In contrast to previous results, the experiments at R-O have been conducted at higher RF-field frequencies and lower electron-ion collision frequencies. The RF-driven current is studied as a function of the plasma parameters. It has been shown experimentally that it is possible to remove the impurity ions when their cyclotron frequency is close to the Alfven wave frequency: #betta#sub(BI) approx.=#betta#sub(A)<<#betta#sub(BiH). The effect of the RF-field on the pre-ionization and current rise stages has been studied in the R-O5 tokamak. The RF-field allows a tokamak discharge at high densities and relatively small magnetic fields to be achieved. In the stationary stage, Alfven heating leads to an increase in the plasma temperature, a rise in #betta#sub(J) (#betta#sub(J) approx.=2-3) and in the confinement time, together with an improvement in MHD stability. (author)