title: Self-regulated oscillation of transport and topology of magnetic islands in toroidal plasmas.
abstract: The coupling between the transport and magnetic topology is an important issue because the structure of magnetic islands, embedded in a toroidal equilibrium field, depends on the nature of the transport at the edge of the islands. Measurements of modulated heat pulse propagation in the DIII-D tokamak have revealed the existence of self-regulated oscillations in the radial energy transport into magnetic islands that are indicative of bifurcations in the island structure and transport near the q = 2 surface. Large amplitude heat pulses are seen in one state followed by small amplitude pulses later in the discharge resulting in a repeating cycle of island states. These two states are interpreted as a bifurcation of magnetic island with high and low heat pulse accessibility. This report describes the discovery of a bifurcation in the coupled dynamics between the transport and topology of magnetic islands in tokamak plasmas.
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ida
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: General Atomics, San Diego, California 92186-5608, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Evans
authors.affiliation: Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8580, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Inagaki
authors.affiliation: University of Texas, Austin, Texas 78712, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Austin
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: M W
authors.initials: MW
authors.lastname: Shafer
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohdachi
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8580, Japan.
authors.forename: S-I
authors.initials: SI
authors.lastname: Itoh
authors.affiliation: National Institute for Fusion Science, Toki, Gifu 509-5292, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Itoh