title: Plasma equilibrium and confinement in a tokamak with nearly zero central current density in JT-60U.
abstract: 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.
authors.affiliation: Japan Atomic Energy Research Institute, Naka Fusion Research Establishment, Naka-machi, Ibaraki-ken, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fujita
authors.forename: T
authors.initials: T
authors.lastname: Oikawa
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: S
authors.initials: S
authors.lastname: Ide
authors.forename: Y
authors.initials: Y
authors.lastname: Sakamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Koide
authors.forename: T
authors.initials: T
authors.lastname: Hatae
authors.forename: O
authors.initials: O
authors.lastname: Naito
authors.forename: A
authors.initials: A
authors.lastname: Isayama
authors.forename: N
authors.initials: N
authors.lastname: Hayashi
authors.forename: H
authors.initials: H
authors.lastname: Shirai