Current clamp at zero level in JT-60U current hole plasmas

Fujita, Takaaki; Suzuki, Takahiro; Oikawa, Toshihiro; Isayama, Akihiko; Hatae, Takaki; Naito, Osamu; Sakamoto, Yoshiteru; Hayashi, Nobuhiko; Hamamatsu, Kiyotaka; Ide, Shunsuke; et al.

Physical Review Letters, 95(7), p.075001_1 - 075001_4, 2005/08

https://doi.org/10.1103/PhysRevLett.95.075001

We found that no current can be driven in a central region of high-temperature, magnetically-confined, axi-symmetric torus plasma once the central current density becomes nearly zero ("current hole"), in spite of high electric conductivity. The current clamp was observed against current drive by a toroidal electric field and a radio-frequency wave in experiments on the JT-60U tokamak. This is a new, stiff, self-organized structure of magnetic field in an axi-symmetric torus plasma.