Observation of Direct Ion Heating in Double-Pulsing CHI in Helicity Injected Spherical Torus Plasmas

Abstract

Anomalous ion heating has been observed for the first time during flux/current amplification by doublepulsing coaxial helicity injection (CHI) in the helicity injected spherical torus (HIST) device. Doppler ion temperature increases significantly near the separatrix on the inboard side during the second CHI pulse, whereas electron temperature remains constant. The experimental results indicate that selective ion heating may be associated with viscous damping of poloidal flows driven by the CHI pulse.

Development of Multichannel Ion Doppler Spectroscopic System by Using Fast Camera

“…Thus, the receiving sensitivity and instrument broadening of the system were analyzed when the width of entrance slit is varied, and the optimal width where the receiving sensitivity is high and the instrument broadening is low was evaluated. The instrument broadening of conventional 1-m Doppler spectroscopic system with multichannel PMT is around 0.03 mm [1,8]. In Fig.…”

“…It was confirmed that the instrument broadening changes linearly at a slit width over 0.05 mm, and the receiving sensitivity saturates at the entrance slit width of 0.08 mm and wider. The instrument broadening of conventional 1-m Doppler spectroscopic system with multichannel PMT is around 0.03 mm [1,8]. In order to compare the proposed system with the measurement result of conventional IDS system, the entrance slit width 0.08 mm was applied in this paper, so that the proposed system can obtain the similar instrument broadening as that of conventional system.…”