Resistive interchange mode destabilized by helically trapped energetic ions and its effects on energetic ions and bulk plasma in a helical plasma

X. D. Du, K. Toi, S. Ohdachi, M. Osakabe, T. Ido, K. Tanaka, M. Yokoyama, M. Yoshinuma, K. Ogawa, K. Y. Watanabe, T. Akiyama, M. Isobe, K. Nagaoka, T. Ozaki, S. Sakakibara, R. Seki, A. Shimizu, Y. Suzuki, H. Tsuchiya

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

A resistive interchange mode of the structure (, : poloidal and toroidal mode numbers, respectively) with a bursting character and rapid frequency chirping in the range less than 10 kHz is observed for the first time in the edge region of the net current-free, low beta LHD (Large Helical Device) plasmas during high power injection of perpendicular neutral beams. The mode resonates with the precession motion of helically trapped energetic ions (EPs), following the resonant condition. The radial mode structure is recognized to be similar to that of the pressure-driven resistive interchange mode, of which radial displacement eigenfunction quite localizes around the mode rational surface, and evolves into an odd-type (or island-type) during the late of frequency chirping phase. This beam driven mode is excited when the beta value of helically trapped EPs exceeds a certain threshold. This instability is thought to be a new branch of resistive interchange mode destabilized by the trapped energetic ions. The radial transport, i.e. redistribution and losses, of helically trapped energetic ions induced by the mode transiently generates significant radial electric field near the plasma peripheral region. The large shear of thus generated radial electric field is thought to contribute to the observed suppression of micro-turbulence and transient increases of the temperature of fully ionized carbon impurity ions and electron density, suggesting improvement of bulk plasma confinement.

Original languageEnglish
Article number016002
JournalNuclear Fusion
Volume56
Issue number1
DOIs
Publication statusPublished - Nov 25 2016

Fingerprint

ions
plasma control
electric fields
neutral beams
precession
eigenvectors
turbulence
retarding
injection
shear
impurities
thresholds
carbon
temperature

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Resistive interchange mode destabilized by helically trapped energetic ions and its effects on energetic ions and bulk plasma in a helical plasma. / Du, X. D.; Toi, K.; Ohdachi, S.; Osakabe, M.; Ido, T.; Tanaka, K.; Yokoyama, M.; Yoshinuma, M.; Ogawa, K.; Watanabe, K. Y.; Akiyama, T.; Isobe, M.; Nagaoka, K.; Ozaki, T.; Sakakibara, S.; Seki, R.; Shimizu, A.; Suzuki, Y.; Tsuchiya, H.

In: Nuclear Fusion, Vol. 56, No. 1, 016002, 25.11.2016.

Research output: Contribution to journalArticle

Du, XD, Toi, K, Ohdachi, S, Osakabe, M, Ido, T, Tanaka, K, Yokoyama, M, Yoshinuma, M, Ogawa, K, Watanabe, KY, Akiyama, T, Isobe, M, Nagaoka, K, Ozaki, T, Sakakibara, S, Seki, R, Shimizu, A, Suzuki, Y & Tsuchiya, H 2016, 'Resistive interchange mode destabilized by helically trapped energetic ions and its effects on energetic ions and bulk plasma in a helical plasma', Nuclear Fusion, vol. 56, no. 1, 016002. https://doi.org/10.1088/0029-5515/56/1/016002
Du, X. D. ; Toi, K. ; Ohdachi, S. ; Osakabe, M. ; Ido, T. ; Tanaka, K. ; Yokoyama, M. ; Yoshinuma, M. ; Ogawa, K. ; Watanabe, K. Y. ; Akiyama, T. ; Isobe, M. ; Nagaoka, K. ; Ozaki, T. ; Sakakibara, S. ; Seki, R. ; Shimizu, A. ; Suzuki, Y. ; Tsuchiya, H. / Resistive interchange mode destabilized by helically trapped energetic ions and its effects on energetic ions and bulk plasma in a helical plasma. In: Nuclear Fusion. 2016 ; Vol. 56, No. 1.
@article{35abf816f1604b5492bc963f3dee5ce3,
title = "Resistive interchange mode destabilized by helically trapped energetic ions and its effects on energetic ions and bulk plasma in a helical plasma",
abstract = "A resistive interchange mode of the structure (, : poloidal and toroidal mode numbers, respectively) with a bursting character and rapid frequency chirping in the range less than 10 kHz is observed for the first time in the edge region of the net current-free, low beta LHD (Large Helical Device) plasmas during high power injection of perpendicular neutral beams. The mode resonates with the precession motion of helically trapped energetic ions (EPs), following the resonant condition. The radial mode structure is recognized to be similar to that of the pressure-driven resistive interchange mode, of which radial displacement eigenfunction quite localizes around the mode rational surface, and evolves into an odd-type (or island-type) during the late of frequency chirping phase. This beam driven mode is excited when the beta value of helically trapped EPs exceeds a certain threshold. This instability is thought to be a new branch of resistive interchange mode destabilized by the trapped energetic ions. The radial transport, i.e. redistribution and losses, of helically trapped energetic ions induced by the mode transiently generates significant radial electric field near the plasma peripheral region. The large shear of thus generated radial electric field is thought to contribute to the observed suppression of micro-turbulence and transient increases of the temperature of fully ionized carbon impurity ions and electron density, suggesting improvement of bulk plasma confinement.",
author = "Du, {X. D.} and K. Toi and S. Ohdachi and M. Osakabe and T. Ido and K. Tanaka and M. Yokoyama and M. Yoshinuma and K. Ogawa and Watanabe, {K. Y.} and T. Akiyama and M. Isobe and K. Nagaoka and T. Ozaki and S. Sakakibara and R. Seki and A. Shimizu and Y. Suzuki and H. Tsuchiya",
year = "2016",
month = "11",
day = "25",
doi = "10.1088/0029-5515/56/1/016002",
language = "English",
volume = "56",
journal = "Nuclear Fusion",
issn = "0029-5515",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Resistive interchange mode destabilized by helically trapped energetic ions and its effects on energetic ions and bulk plasma in a helical plasma

AU - Du, X. D.

AU - Toi, K.

AU - Ohdachi, S.

AU - Osakabe, M.

AU - Ido, T.

AU - Tanaka, K.

AU - Yokoyama, M.

AU - Yoshinuma, M.

AU - Ogawa, K.

AU - Watanabe, K. Y.

AU - Akiyama, T.

AU - Isobe, M.

AU - Nagaoka, K.

AU - Ozaki, T.

AU - Sakakibara, S.

AU - Seki, R.

AU - Shimizu, A.

AU - Suzuki, Y.

AU - Tsuchiya, H.

PY - 2016/11/25

Y1 - 2016/11/25

N2 - A resistive interchange mode of the structure (, : poloidal and toroidal mode numbers, respectively) with a bursting character and rapid frequency chirping in the range less than 10 kHz is observed for the first time in the edge region of the net current-free, low beta LHD (Large Helical Device) plasmas during high power injection of perpendicular neutral beams. The mode resonates with the precession motion of helically trapped energetic ions (EPs), following the resonant condition. The radial mode structure is recognized to be similar to that of the pressure-driven resistive interchange mode, of which radial displacement eigenfunction quite localizes around the mode rational surface, and evolves into an odd-type (or island-type) during the late of frequency chirping phase. This beam driven mode is excited when the beta value of helically trapped EPs exceeds a certain threshold. This instability is thought to be a new branch of resistive interchange mode destabilized by the trapped energetic ions. The radial transport, i.e. redistribution and losses, of helically trapped energetic ions induced by the mode transiently generates significant radial electric field near the plasma peripheral region. The large shear of thus generated radial electric field is thought to contribute to the observed suppression of micro-turbulence and transient increases of the temperature of fully ionized carbon impurity ions and electron density, suggesting improvement of bulk plasma confinement.

AB - A resistive interchange mode of the structure (, : poloidal and toroidal mode numbers, respectively) with a bursting character and rapid frequency chirping in the range less than 10 kHz is observed for the first time in the edge region of the net current-free, low beta LHD (Large Helical Device) plasmas during high power injection of perpendicular neutral beams. The mode resonates with the precession motion of helically trapped energetic ions (EPs), following the resonant condition. The radial mode structure is recognized to be similar to that of the pressure-driven resistive interchange mode, of which radial displacement eigenfunction quite localizes around the mode rational surface, and evolves into an odd-type (or island-type) during the late of frequency chirping phase. This beam driven mode is excited when the beta value of helically trapped EPs exceeds a certain threshold. This instability is thought to be a new branch of resistive interchange mode destabilized by the trapped energetic ions. The radial transport, i.e. redistribution and losses, of helically trapped energetic ions induced by the mode transiently generates significant radial electric field near the plasma peripheral region. The large shear of thus generated radial electric field is thought to contribute to the observed suppression of micro-turbulence and transient increases of the temperature of fully ionized carbon impurity ions and electron density, suggesting improvement of bulk plasma confinement.

UR - http://www.scopus.com/inward/record.url?scp=84948185876&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84948185876&partnerID=8YFLogxK

U2 - 10.1088/0029-5515/56/1/016002

DO - 10.1088/0029-5515/56/1/016002

M3 - Article

AN - SCOPUS:84948185876

VL - 56

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 1

M1 - 016002

ER -