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.
Publisher Copyright:
© 2017 IOP Publishing Ltd.
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 -