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 AMreflectometer. SMBI affects particle confinement and transport, thus possibly increasing plasma stored energy. © 2011 The Japan Society of Plasma Science and Nuclear Fusion Research.