Electron thermal transport induced by magnetic turbulence in the HT-7 tokamak

An inserted magnetic probe was used to simultaneously measure the poloidal and radial magnetic fluctuations from (normalized minor radius) ρ = 1.1 to ρ = 0.8 in the HT-7 tokamak. It is found that when the magnetic probe was gradually moved inward the magnetic fluctuation levels continually increased and did not show saturation tendency. The electron thermal transport induced by magnetic turbulence is quite small in the HT-7 tokamak. By calculating the propagation velocity along the poloidal direction, it was found that this velocity is very close to the electrostatic turbulence phase velocity at the plasma edge. So it leads us to consider that the magnetic fluctuations may be coupled with the electrostatic drift waves. This experimental finding implies that the magnetic turbulence is possibly not an independent mode, instead it seems to be more an intrinsic component of the basic underlying micro-instability.