Turbulence and transport studies in the edge plasma of the HT-7 tokamak

摘要

The edge fluctuations and transport in the HT-7 tokamak are investigated using a Langmuir probe array in ohmic and IBW heated discharges. The normalized fluctuation levels are in the range 15-60/100 for electron density and temperature, respectively, and have the non-Boltzmann relation eV_f/T_e＞n_e_e＞T_e/T_e in the Sol of the ohmically heated plasmas. The fluctuation spectra show typical broadband features as observed in other tokamaks. In IBW heated plasmas, the particle confinement is greatly improved and the poloidal velocity shear in the SOL is strongly modified in a manner that is equivalent to an additional poloidal velocity in the electron diamagnetic direction produced by the IBW.