Gas puff imaging measurements during resonant magnetic perturbations on the HL-2A tokamak

Gas puff imaging measurements during resonant magnetic perturbations on the HL-2A tokamak

Blog Article

The gas puff imaging diagnostic is used for the investigation of the poloidal flow and turbulent fluctuations at the plasma edge and scrape-off layer (SOL) on the HL-2A tokamak.The impact of resonant magnetic perturbations (RMPs) on the edge poloidal velocity ( ${V_ heta }$ ) are investigated and compared during the operation of a stair-like rising RMP coil current ( ${I_{{ ext{RMP}}}}$ ).The application of the RMP is observed to modify the poloidal velocity significantly.When ${I_{{ ext{RMP}}}}$ exceeds 4 kA, the turbulence poloidal velocity at the Butt edge changes direction from electron to ion diamagnetic drift.This phenomenon is explained by the electron loss along the perturbed radial magnetic field $({B_r})$ with RMP, with the experimental evidence provided that the edge electric potential Swag increases significantly.

A strong impact of the RMP on the properties of plasma density fluctuations in the SOL is also observed.With RMP, both skewness and kurtosis are smaller in the SOL and large-scale turbulence structures (small ${k_r}$ and ${k_ heta }$ ) are suppressed in both edge and SOL.These results can improve our understanding of the interaction between RMP and edge turbulence and in particular, the edge poloidal flow.