Boundary turbulence and transport in density scanning experiment on TH-7 tokamak
在HT-7托卡马克上密度扫描实验中的边界湍流和输运

The boundary turbulence and transport in density scanning experiment were investigated using a fast reciprocating Langmuir probe in the HT-7 tokamak.With the increase of the central line averaged plasma density, an enhanced shear of the radial electric field was observed at plasma edge, which could account for the reduction of edge transport and the improvement of global particle confinement. The reduced particle transport was demonstrated by the increase of the particle confinement time and the decrease of the perpendicular diffusion coefficient. The features of the ionization-and-radiation-driven turbulence, ${\tilde {T}_\e } \mathord{\left/{\vphantom {{\tilde {T}_\e } {T_\e }}} \right. \kern-\nulldelimiterspace} {T_\e}\sim {\tilde {n}_\e } \mathord{\left/ {\vphantom {{\tilde {n}_\e } {n_\e }}}\right. \kern-\nulldelimiterspace} {n_\e }$ and $\theta \_\tilde {T}_\e \tilde {n}_\e \sim \pi $, were found in the plasma edge region, which suggests the importance of the ionization and radiation in the turbulence driving.