Plasma equilibrium and confinement in a tokamak with nearly zero central current density in JT-60U
Plasma equilibrium and confinement in a tokamak with nearly zero central current density in JT-60U
复制标题
DOI：
10.1103/physrevlett.87.085001
复制
发表时间：
2001-12-10
影响因子：
8.6
通讯作者：
Shirai, H
中科院分区：
文献类型：
--
作者：
Fujita, T;Oikawa, T;Shirai, H
在JT-60U托卡马克中首次获得了具有大自举电流分数（接近80%）的准稳态反剪切等离子体。反向剪切区域的收缩受到内部传输势垒（ITB）层峰值的自举电流的抑制，并且大半径的ITB得以维持。通过与 H 模式边缘基座相结合，可实现高限制或 2.2 倍的 H 模式缩放，同时能量限制时间为 6 倍或 2.7 秒。此外，通过自举电流和束流驱动电流获得了完全无感电流驱动。在JT-60U托卡马克中首次观察到中心区域（“电流孔”）环形电流几乎为零的高约束平衡，并稳定持续数秒。这一观察结果表明托卡马克在没有中心环形电流的情况下稳定运行的可能性；此前人们认为中心电流对于托卡马克来说是必要的。当前孔的半径延伸至等离子体小半径的40%。观察到电流空穴是由于离轴无感电流的增加而形成的。
A quasisteady reversed shear plasma with a large bootstrap current fraction (similar to 80%) has been obtained for the first time in the JT-60U tokamak. The shrinkage of reversed shear region was suppressed by the bootstrap current peaked at the internal transport barrier (ITB) layer and the ITBs at a large radius were sustained. which, by combination with an H-mode edge pedestal, resulted in a high confinement or 2.2 times the H-mode scaling for 6 times energy confinement time or 2.7 s. Furthermore, a full noninductive current drive was obtained by the bootstrap current and the beam driven current.A high confinement equilibrium with nearly zero toroidal current in the central region (a "current hole") has been observed for the first time to persist stably for several seconds in the JT-60U tokamak. This observation indicates the possibility of stable tokamak operation without central toroidal current; the central current has previously been believed to be necessary in tokamaks. The radius of the current hole extended up to 40% of the plasma minor radius. It was observed that the current hole was formed by the increase of the off-axis noninductive current.