Temporal Behavior of the Electron Density Profile During Limiter Biasing in the HYBTOK-II Tokamak

A rapid change in the detailed edge electron density profile during positively biased limiter experiment is obtained with high temporal resolution of ∼20 μs using a laser blowoff lithium beam probe technique in HYBTOK‐II tokamak [IEEE Trans. Plasma Sci. PS‐19, 885 (1991)]. The transient change in the electron density profile and the movement of the position where a steep density gradient is formed are experimentally observed. The temporal behavior of the electron density profile correlates well with reductions in the biasing current and Hα emission in the scrape‐off layer, and the suppression of electrostatic fluctuations near the edge of the core region.