Abstract
A 20 channel PIN-photodiode array is installed on the compact helical system (CHS) heliotron/torsatron to measure the radial profiles of soft x-ray (SXR) emission and fluctuations. In neutral beam injection (NBI) heated plasma on CHS, sawtooth oscillations are often observed in the SXR signals. The sawtooth has a characteristic feature of the off-axis sawtooth crash that takes place first near the 1/q=1/2 rational surface located at the normalized minor radius ρ≈0.4−0.6, where q is the safety factor. In most of cases high frequency precursor and low frequency postcursor oscillations having m/n=2/1 mode structure (m, n: the poloidal and toroidal mode numbers) appear before and after the crash. The total plasma beta derived from the measurement of SXR emission-peak position is slightly but clearly decreased by the sawtooth crash. This reduction suggests rapid transport of energetic beam ions from the core region toward the plasma edge region.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
