title: Abrupt onset of tongue deformation and phase space response of ions in magnetically-confined plasmas.
abstract: An abrupt onset of the new tongue-shaped deformation of magnetic surface in magnetized plasmas, which was conjectured in since the 1960s but has not been observed, is experimentally identified just before an abrupt onset of a large-scale collapse event. Two novel properties of the event are identified. First, the transition of symmetry of perturbation (rather than a growth of linearly unstable MHD modes) was found to be a key for the onset of abrupt collapse, i.e., the transition of symmetry gives a new route to the collapse from stable state. Second, as a phase-space response of ions, the distortion from Maxwell-Boltzmann distribution of epithermal ions was observed for the first time.
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.|SOKENDAI (The Graduate University for Advanced Studies), 322-6 Oroshi, Toki, Gifu 509-5292, Japan.
authors: K
authors: K
authors: Ida
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.|SOKENDAI (The Graduate University for Advanced Studies), 322-6 Oroshi, Toki, Gifu 509-5292, Japan.
authors: T
authors: T
authors: Kobayashi
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.
authors: K
authors: K
authors: Itoh
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.
authors: M
authors: M
authors: Yoshinuma
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.
authors: T
authors: T
authors: Tokuzawa
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.
authors: T
authors: T
authors: Akiyama
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.
authors: C
authors: C
authors: Moon
authors: National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292, Japan.
authors: H
authors: H
authors: Tsuchiya
authors: Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8580, Japan.
authors: S
authors: S
authors: Inagaki
authors: Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, 816-8580, Japan.
authors: S-I
authors: SI
authors: Itoh