Electron Density Profile Behavior during SMBI Measured with AM Reflectometer in Heliotron J Plasma

Abstract

The electron density profile was measured using a microwave amplitude modulation (AM) reflectometer in Heliotron J plasmas, where plasma performance was improved using supersonic molecular beam injection (SMBI) as a fueling method. Immediately after the SMBI pulse, for the case in which the supersonic molecular beam penetrates deeply, the density profile rapidly peaks, and the electron density increases in both core and edge regions. Afterward, while the line-averaged electron density is monotonically increasing, the density profile becomes more peaked. In this phase, the edge electron density measured by a Langmuir probe decreases and the peaking factor of the SX profiles measured by an absolute extreme ultraviolet array increases. These trends are consistent with the electron density trend determined by the AM reflectometer. SMBI affects particle confinement and transport, thus possibly increasing plasma stored energy.

Edge turbulence measurement in Heliotron J using a combination of hybrid probe system and fast cameras

“…It was thought that the neutral particles from SMBI diffused in the small region at plasma surface ($10 cm) by FX K5 camera images and at #14.5 SA5 camera did not see the increment of the neutral particles due to SMBI directly. Just after SMBI the electron temperature decreased and the profile of the electron density was somewhat peaked [31]. Therefore, at #14.5 toroidal region the increment of the emission was thought to be due to the increment of the peripheral electron density.…”

“…Therefore, if the edge electron density would be proportional to the line integrated electron density, the phase velocity was decreased with the electron density increase. In this shot SMBI used at $220 ms (between 208 ms and 240 ms), thus, the electron density profile should be changed [31,34].…”

First Application of an InfraRed Imaging Video Bolometer to Heliotron J Plasma

“…The upper region views the plasma core and has a larger ΔT increase than the other regions. The Absolute eXtreme UltraViolet (AXUV) intensity also has larger signals in the line of sight, where the plasma core is viewed [4,5]. Although the EMC3-EIRENE calculation result should not be directly compared to the IRVB results, due to the exclusion of radiation from the core, no response is found in the foil region with no plasma, as expected in the EMC3-EIRENE modeling.…”