ELECTRON HEATING AND ANOMALOUS TRANSPORT IN THE INITIAL STAGE OF TURBULENT HEATING OF A PLASMA

概要

論文の詳細を見る
Initial stage of a linear turbulent heating of a plasma has been investigated by use of Thomson scattering of ruby laser light with an eight channel polychromator. In a low density discharge (n ≃ 5×10^<12> cm^<-3>), an anomalously rapid electron heating was observed associated with the appearance of high frequency fluctuations (ω ≲ ω_<pi>), which were considered to be current driven ion acoustic waves. Flat-top velocity distribution of the electrons were also observed just after the onset of the ion acoustic instability. Formation of this flat-top distribution was interpreted as a quasilinear diffusion process in velocity space in the presence of ion acoustic waves. In a high density discharge (n ≃ 2×10^<14> cm^<-3>), it was found that the skin current distribution was rapidly destroyed, while skin profile of the radial distribution of the electron temperature remained rather longer, indicating that the plasma current redistributed without electron heat transfer across the magnetic field. The anomalous resistivity caused by ion acoustic waves was essential for the anomalously rapid current penetration.