Role of electric field curvature in the formation of edge transport barrier in the JT-60U tokamak. (31st October 2017)

• Record Type: Journal Article
• Authors: Kamiya, K; Itoh, K; Itoh, S-I; Ida, K; Kobayashi, T
• Is Part Of: Plasma physics and controlled fusion. Volume 60:Number 1(2018:Jan.)
• Publication Date: 2017-10-31
• Subjects: H-mode -- pedestal -- radial electric field; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/1361-6587/aa8a01
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: Based on the high-resolution spectroscopic measurements of the radial electric field ( E r ) in the JT-60U tokamak, we have identified the mechanisms centered around the role of the E r -curvature on the edge transport barrier (ETB) formation. In addition, we recognized a new role of the E r -shear for the expansion of pedestal width, compensating an unfavorable effect of the E r -curvature having its sign dependence on the turbulence transport. We found a new interesting phenomenon of very slow out-of-phase oscillations between the E r and ion temperature gradient in the frequency range of 30–50 Hz, preceding the slow L-H transition, which can demonstrate a causality test of the ETB formation in association with the non-uniformity E r -effects. A critical condition for the E r -bifurcations is also discussed.