Potential and density/temperature fluctuations at the L-H transition are measured by a heavy ion beam probe (HIBP) on JFT-2M. It has been observed that the time scale of potential change is as fast as 10-100 μ,s when the input power (Pin) is larger than the L-H threshold power (Pth). When Pin = Pth, the confinement is improved step by step, with sawteeth crashes accompanied by a decrease of potential. After a few sawteeth crashes, the potential drops rapidly to the level of the ELM-free H-mode. At that time, the density/temperature fluctuations are suppressed simultaneously. The observations of the temporal behaviour of the potential and fluctuations in such an L-H transition are reported.
All Science Journal Classification (ASJC) codes
- Nuclear Energy and Engineering
- Condensed Matter Physics