Toroidal alfven eigenmodes driven with JCRF accelerated protons in JT-60U negative shear discharges

摘要

On JT-60U, for the first time in negative plasmas, toroidicity induced Alfven eigenmodes(TAEs)with frequencies in the range of 90 to 110 kHz and toroidal mode numbers n=5-8 were observed after a broadening of the density profile due to sequential partial collapses during ion cyclotron range of frequency(ICRF)heating. TAEs are more stable in negative shear plasmas than plasmas with a monotonically increasing q profile. The TAE stability was analysed with the NOVA-K code. It was found that the stability is highly sensitive to the gap alignment just inside q_min and that the theoretical results are consistent with the experimental results.