TY - JOUR
T1 - Comparison of electron internal transport barriers in the large helical device and JT-60U plasmas
AU - Ida, K.
AU - Fujita, T.
AU - Fukuda, T.
AU - Sakamoto, Y.
AU - Ide, S.
AU - Toi, K.
AU - Inagakl, S.
AU - Shimozuma, T.
AU - Kubo, S.
AU - Idei, H.
AU - Fujisawa, A.
AU - Ohdachi, S.
AU - Yoshinuma, M.
AU - Funaba, H.
AU - Narihara, K.
AU - Murakami, S.
AU - Wakasa, A.
AU - Yokoyama, M.
AU - Takeiri, Y.
AU - Watanabe, K. Y.
AU - Tanaka, K.
AU - Liang, Y.
AU - Ohyabu, N.
PY - 2004/5
Y1 - 2004/5
N2 - Plasmas with an electron internal transport barrier (ITB), which is characterized by peaked electron temperature profiles, are obtained in the JT-60U tokamak and in the large helical device (LHD) when the electron cyclotron heating (ECH) is focused on the magnetic axis. The maximum values of R/L Te, where R is the major radius and LTe is the scale length of the electron temperature gradient, are similar for the LHD and JT-60U ITB plasmas. However, there is a clear jump of R/LTe observed in LHD but not in JT-60U in the ECH power scan. This result is consistent with the fact that the trigger mechanism of the electron ITB is the fast transition of the radial electric field from a small negative Er to a large positive Er in LHD and a change of the magnetic shear from positive to negative is required for the formation of the electron ITB in JT-60U. There are also differences in the electron temperature profiles inside the ITB. The flattening of the electron temperature profile inside the strong ITB could be explained by the sharp increase of q values observed in JT-60U, while no flattening of the electron temperature profile is observed in LHD, where the central q values stay low.
AB - Plasmas with an electron internal transport barrier (ITB), which is characterized by peaked electron temperature profiles, are obtained in the JT-60U tokamak and in the large helical device (LHD) when the electron cyclotron heating (ECH) is focused on the magnetic axis. The maximum values of R/L Te, where R is the major radius and LTe is the scale length of the electron temperature gradient, are similar for the LHD and JT-60U ITB plasmas. However, there is a clear jump of R/LTe observed in LHD but not in JT-60U in the ECH power scan. This result is consistent with the fact that the trigger mechanism of the electron ITB is the fast transition of the radial electric field from a small negative Er to a large positive Er in LHD and a change of the magnetic shear from positive to negative is required for the formation of the electron ITB in JT-60U. There are also differences in the electron temperature profiles inside the ITB. The flattening of the electron temperature profile inside the strong ITB could be explained by the sharp increase of q values observed in JT-60U, while no flattening of the electron temperature profile is observed in LHD, where the central q values stay low.
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U2 - 10.1088/0741-3335/46/5A/004
DO - 10.1088/0741-3335/46/5A/004
M3 - Article
AN - SCOPUS:2942589199
SN - 0741-3335
VL - 46
SP - A45-A50
JO - Plasma Physics and Controlled Fusion
JF - Plasma Physics and Controlled Fusion
IS - 5 SUPPL. A
ER -