TY - JOUR
T1 - Role of electric field curvature in the formation of edge transport barrier in the JT-60U tokamak
AU - Kamiya, K.
AU - Itoh, K.
AU - Itoh, S. I.
AU - Ida, K.
AU - Kobayashi, T.
N1 - Funding Information:
The authors deeply appreciate the continued research and operational effort of the entire JT-60 team. Discussions with Prof P H Diamond, Prof U Stroth and Prof J Q Dong are also acknowledged. The authors acknowledge the partial support by Grant-in-Aid for Scientific Research (JP 15K06657, JP 15H02155, JP 16H02442) and collaboration programs between QST and universities and of the RIAM of Kyushu University, and by Asada Science Foundation.
PY - 2018/1
Y1 - 2018/1
N2 - 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.
AB - 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.
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U2 - 10.1088/1361-6587/aa8a01
DO - 10.1088/1361-6587/aa8a01
M3 - Article
AN - SCOPUS:85038411835
VL - 60
JO - Plasma Physics and Controlled Fusion
JF - Plasma Physics and Controlled Fusion
SN - 0741-3335
IS - 1
M1 - 014023
ER -