Experimental validation of non-uniformity effect of the radial electric field on the edge transport barrier formation in JT-60U H-mode plasmas

H-mode輸送障壁における電場不均一性の効果の検証

神谷 健作; 伊藤 公孝*; 伊藤 早苗*

Kamiya, Kensaku; Ito, Kimitaka*; Ito, Sanae*

JT-60Uにおける高分解能での周辺径電場計測結果をもとに、今回初めて径電場シア及び曲率の輸送障壁形成に対する効果を調べた。径電場シア及び曲率の各項はドリフト波揺動の散逸及びコヒーレントなエネルギー転換における非線形過程に本質的に連関するので、それぞれについて調べたところ、規格化イオン温度勾配のピーク位置では、電場シア項は周辺輸送障壁形成と大きな相関は無く、他方電場曲率項が重要な役割を果たしていることが分かった。

Based on high-spatiotemporal resolution spectroscopic measurements of the edge radial electric field from the JT-60U tokamak, we examined the effects of both shear and curvature on the edge transport barriers (ETBs) formation for the first time. These two correspond to the essential nonlinear processes in drift wave fluctuations, i.e., the enhanced dissipation and the convergence into coherent axial vector fields, respectively, and are examined separately. While there was only a low correlation between the first derivative effect and ETBs formation at which the normalized ion temperature gradient had a local peak value, we found the importance of second derivative effect.