Fast wave current drive experiment on the JFT-2M tokamak

First, a 200 MHz fast wave (FW) experiment for the JFT-2M tokamak is examined theoretically. Noticeable single-path electron Landau damping of the FW with the parallel refractive index of Nparallel =4 is expected in the plasma with electron temperature more than 2.5 keV at the electron density of ne=1.5x1019m-3. In addition, it is predicted that an 8 kA of the plasma current is driven by the FW with Nparallel =2 at ne=3x1019m-3 in single-path damping when 100 kW of the rf power radiates into the plasma in the presence of hot electrons with the temperature of 19 keV and the fraction of the density of 2%. Next, initial results on the FW experiment with 80 kW of the RF power are reported. A phased loop antenna array is employed to launch the FW into a plasma in which the wave frequency is of the order of 10fci. A high loading resistance of about 5 Ω is obtained and its value agrees well with the theoretical estimation. The loading efficiency of about 80% is obtained. For n-bare<2x1018, the current drive is observed. The density limit is also observed and correlates with the excitation of parametric instabilities. These results are similar to those of LHCD with the frequency of 0.75 GHz except a critical density. (author)