DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas

Abstract

Bifurcation physics of the magnetic island was investigated using the heat pulse propagation technique produced by the modulation of electron cyclotron heating. There are two types of bifurcation phenomena observed in LHD and DIII-D. One is a bifurcation of the magnetic topology between nested and stochastic fields. The nested state is characterized by the bi-directional (inward and outward) propagation of the heat pulse with slow propagation speed. The stochastic state is characterized by the fast propagation of the heat pulse with electron temperature flattening. The other bifurcation is between magnetic island with larger thermal diffusivity and that with smaller thermal diffusivity. The damping of toroidal flow is observed at the O-point of the magnetic island both in helical plasmas and in tokamak plasmas during a mode locking phase with strong flow shears at the boundary of the magnetic island. Associated with the stochastization of the magnetic field, the abrupt damping of toroidal flow is observed in LHD. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. Lastly, this observation suggests that this flow damping is due to the change in the non-diffusive term of momentum transport.

Authors:
 [1];  [2];  [2];  [1];  [1];  [3];  [1];  [2];  [4];  [2]
  1. National Inst. for Fusion Science, Toki (Japan); Graduate Univ. for Advanced Studies, Toki (Japan)
  2. National Inst. for Fusion Science, Toki (Japan)
  3. General Atomics, San Diego, CA (United States)
  4. Kyushu Univ., Kasuga (Japan). Research Inst. for Applied Mechanics
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE; National Institute for Fusion Science (NIFS-NINS)
OSTI Identifier:
1375943
Grant/Contract Number:  
FC02-04ER54698; FG03-97ER54415; AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 9; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; stochasticity; magnetic island; bifurcation; heat pulse propagation

Citation Formats

Ida, K., Kobayashi, T., Yoshinuma, M., Suzuki, Y., Narushima, Y., Evans, T. E., Ohdachi, S., Tsuchiya, H., Inagaki, S., and Itoh, K. Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas. United States: N. p., 2016. Web. doi:10.1088/0029-5515/56/9/092001.
Ida, K., Kobayashi, T., Yoshinuma, M., Suzuki, Y., Narushima, Y., Evans, T. E., Ohdachi, S., Tsuchiya, H., Inagaki, S., & Itoh, K. Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas. United States. https://doi.org/10.1088/0029-5515/56/9/092001
Ida, K., Kobayashi, T., Yoshinuma, M., Suzuki, Y., Narushima, Y., Evans, T. E., Ohdachi, S., Tsuchiya, H., Inagaki, S., and Itoh, K. Fri . "Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas". United States. https://doi.org/10.1088/0029-5515/56/9/092001. https://www.osti.gov/servlets/purl/1375943.
@article{osti_1375943,
title = {Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas},
author = {Ida, K. and Kobayashi, T. and Yoshinuma, M. and Suzuki, Y. and Narushima, Y. and Evans, T. E. and Ohdachi, S. and Tsuchiya, H. and Inagaki, S. and Itoh, K.},
abstractNote = {Bifurcation physics of the magnetic island was investigated using the heat pulse propagation technique produced by the modulation of electron cyclotron heating. There are two types of bifurcation phenomena observed in LHD and DIII-D. One is a bifurcation of the magnetic topology between nested and stochastic fields. The nested state is characterized by the bi-directional (inward and outward) propagation of the heat pulse with slow propagation speed. The stochastic state is characterized by the fast propagation of the heat pulse with electron temperature flattening. The other bifurcation is between magnetic island with larger thermal diffusivity and that with smaller thermal diffusivity. The damping of toroidal flow is observed at the O-point of the magnetic island both in helical plasmas and in tokamak plasmas during a mode locking phase with strong flow shears at the boundary of the magnetic island. Associated with the stochastization of the magnetic field, the abrupt damping of toroidal flow is observed in LHD. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. Lastly, this observation suggests that this flow damping is due to the change in the non-diffusive term of momentum transport.},
doi = {10.1088/0029-5515/56/9/092001},
journal = {Nuclear Fusion},
number = 9,
volume = 56,
place = {United States},
year = {Fri Jul 29 00:00:00 EDT 2016},
month = {Fri Jul 29 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 16 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Higher Harmonics in the Perturbative Transport Study in TJ-II ECH Plasma
journal, January 2014

  • Inagaki, Shigeru; Itoh, Sanae-I.; Itoh, Kimitaka
  • Plasma and Fusion Research, Vol. 9, Issue 0
  • DOI: 10.1585/pfr.9.1202052

Bifurcation Phenomena of a Magnetic Island at a Rational Surface in a Magnetic-Shear Control Experiment
journal, January 2008


Temperature profile perturbations due to magnetic islands in TEXTOR
journal, March 1997

  • Vries, P. C. de; Waidmann, G.; Krämer-Flecken, A.
  • Plasma Physics and Controlled Fusion, Vol. 39, Issue 3
  • DOI: 10.1088/0741-3335/39/3/008

Threshold for metastable tearing modes in DIII-D
journal, July 1998


Beta limits in long-pulse tokamak discharges
journal, May 1997

  • Sauter, O.; La Haye, R. J.; Chang, Z.
  • Physics of Plasmas, Vol. 4, Issue 5
  • DOI: 10.1063/1.872270

Self-regulated oscillation of transport and topology of magnetic islands in toroidal plasmas
journal, November 2015

  • Ida, K.; Kobayashi, T.; Evans, T. E.
  • Scientific Reports, Vol. 5, Issue 1
  • DOI: 10.1038/srep16165

Some effects of MHD activity on impurity transport in the PBX Tokamak
journal, June 1986


Nonlinear evolution of tearing modes in inhomogeneous plasmas
journal, June 1993


Multi-mode error field correction on the DIII-D tokamak
journal, March 2003


What is the condition for fast magnetic reconnection?
journal, December 1994

  • Yokoyama, T.; Shibata, K.
  • The Astrophysical Journal, Vol. 436
  • DOI: 10.1086/187666

Forced magnetic reconnection
journal, January 1985

  • Hahm, T. S.; Kulsrud, R. M.
  • Physics of Fluids, Vol. 28, Issue 8
  • DOI: 10.1063/1.865247

Complete suppression of the m = 2/ n = 1 neoclassical tearing mode using electron cyclotron current drive in DIII-D
journal, January 2004


Verification of wavelet analysis for a heat pulse propagation experiment
journal, August 2011


Model of the major disruption in tokamaks
journal, October 1992


Flow damping due to stochastization of the magnetic field
journal, January 2015

  • Ida, K.; Yoshinuma, M.; Tsuchiya, H.
  • Nature Communications, Vol. 6, Issue 1
  • DOI: 10.1038/ncomms6816

Transitions to improved core electron heat confinement triggered by low order rational magnetic surfaces in the stellarator TJ-II
journal, March 2007


Stabilization of neoclassical tearing modes by electron cyclotron current drive
journal, September 1997


Development and application of HINT2 to helical system plasmas
journal, September 2006


Fluctuations, sheared radial electric fields and transport interplay in fusion plasmas
journal, July 2002


The stochastic diffusion process in reversed‐field pinch
journal, June 1996

  • D’Angelo, F.; Paccagnella, R.
  • Physics of Plasmas, Vol. 3, Issue 6
  • DOI: 10.1063/1.871919

Use of a twisted 3D Cauchy condition surface to reconstruct the last closed magnetic surface in a non-axisymmetric fusion plasma
journal, November 2012


Dynamics of turbulence spreading in magnetically confined plasmas
journal, March 2005

  • Gürcan, Ö. D.; Diamond, P. H.; Hahm, T. S.
  • Physics of Plasmas, Vol. 12, Issue 3
  • DOI: 10.1063/1.1853385

New Method of Analysis for Dynamical Transport
journal, January 2013

  • Inagaki, Shigeru; Tokuzawa, Tokihiko; Kobayashi, Tatsuya
  • Plasma and Fusion Research, Vol. 8, Issue 0
  • DOI: 10.1585/pfr.8.1202172

Ambipolar magnetic fluctuation‐induced heat transport in toroidal devices
journal, May 1996

  • Terry, P. W.; Fiksel, G.; Ji, H.
  • Physics of Plasmas, Vol. 3, Issue 5
  • DOI: 10.1063/1.871996

Helical temperature perturbations associated with tearing modes in tokamak plasmas
journal, March 1995

  • Fitzpatrick, Richard
  • Physics of Plasmas, Vol. 2, Issue 3
  • DOI: 10.1063/1.871434

Fast transport changes and power degradation in the W7-AS stellarator
journal, April 1996


Self-organized helical equilibria as a new paradigm for ohmically heated fusion plasmas
journal, June 2009

  • Lorenzini, R.; Martines, E.; Piovesan, P.
  • Nature Physics, Vol. 5, Issue 8
  • DOI: 10.1038/nphys1308

Disruptions in JET
journal, April 1989


Experimental observation of response to resonant magnetic perturbation and its hysteresis in LHD
journal, June 2015


Measurement of magnetic island width in long-pulse, high- discharges in JT-60U
journal, January 1999


How is turbulence intensity determined by macroscopic variables in a toroidal plasma?
journal, September 2013


Electron thermal transport within magnetic islands in the reversed-field pinch
journal, May 2010

  • Stephens, H. D.; Den Hartog, D. J.; Hegna, C. C.
  • Physics of Plasmas, Vol. 17, Issue 5
  • DOI: 10.1063/1.3388374

Electromagnetic effects on toroidal momentum transport
journal, December 2010

  • Mahmood, M. Ansar; Eriksson, A.; Weiland, J.
  • Physics of Plasmas, Vol. 17, Issue 12
  • DOI: 10.1063/1.3511441

Heat pulse propagation across the rational surface in a large helical device plasma with counter-neutral beam injection
journal, September 2005

  • Yakovlev, M.; Inagaki, S.; Shimozuma, T.
  • Physics of Plasmas, Vol. 12, Issue 9
  • DOI: 10.1063/1.2044447

Internal transport barrier triggering by rational magnetic flux surfaces in tokamaks
journal, September 2003


Island Dynamics in the Large-Helical-Device Plasmas
journal, January 2002


Heat pulse propagation studies around magnetic islands induced by the Dynamic Ergodic Divertor in TEXTOR
journal, September 2008


Neoclassical tearing mode control using electron cyclotron current drive and magnetic island evolution in JT-60U
journal, April 2009


A design retrospective of the DIII-D tokamak
journal, May 2002


Nonlinear coupling of tearing modes with self-consistent resistivity evolution in tokamaks
journal, January 1980

  • Carreras, B.; Hicks, H. R.; Holmes, J. A.
  • Physics of Fluids, Vol. 23, Issue 9
  • DOI: 10.1063/1.863206

Role of plasma response in displacements of the tokamak edge due to applied non-axisymmetric fields
journal, June 2013


Gradients of electron temperature and density across m = 2 magnetic islands in RTP
journal, August 1993

  • Milligen, B. P. van; Lammeren, A. C. A. P. van; Cardozo, N. J. Lopes
  • Nuclear Fusion, Vol. 33, Issue 8
  • DOI: 10.1088/0029-5515/33/8/i03

Edge stability and transport control with resonant magnetic perturbations in collisionless tokamak plasmas
journal, May 2006

  • Evans, Todd E.; Moyer, Richard A.; Burrell, Keith H.
  • Nature Physics, Vol. 2, Issue 6
  • DOI: 10.1038/nphys312

Perturbative studies of transport phenomena in fusion devices
journal, November 2010


The Solar-Flare Phenomenon and the Theory of Reconnection and Annihiliation of Magnetic Fields.
journal, July 1963

  • Parker, E. N.
  • The Astrophysical Journal Supplement Series, Vol. 8
  • DOI: 10.1086/190087

Tokamak-like confinement at a high beta and low toroidal field in the MST reversed field pinch
journal, December 2003


Transport and confinement studies in the RFX-mod reversed-field pinch experiment
journal, August 2007


Self-sustained annihilation of magnetic islands in helical plasmas
journal, July 2005

  • Itoh, Kimitaka; Itoh, Sanae-I.; Yagi, Masatoshi
  • Physics of Plasmas, Vol. 12, Issue 7
  • DOI: 10.1063/1.1946731

Operational conditions and characteristics of ELM-events during H-mode plasmas in the stellarator W7-AS
journal, May 2000


Perturbative transport studies in fusion plasmas
journal, August 1995


Reduction of Ion Thermal Diffusivity Inside a Magnetic Island in JT-60U Tokamak Plasma
journal, August 2012


Observation of Nonlinear Neoclassical Pressure-Gradient–Driven Tearing Modes in TFTR
journal, June 1995


Neoclassical Tearing Physics in the Spherical Tokamak MAST
journal, March 2002


Effect of Heating on the Suppression of Tearing Modes in Tokamaks
journal, January 2007


Observation of the “Self-Healing” of an Error Field Island in the Large Helical Device
journal, September 2001


Persistent density perturbations at rational- q surfaces following pellet injection in the Joint European Torus
journal, November 1987


Density profile peaking inside m/n=2/1 magnetic islands in TEXTOR-94
journal, November 1997


Internal transport barrier on q =3 surface and poloidal plasma spin up in JT-60U high- β p discharges
journal, June 1994


Generation of sheared poloidal flows via Reynolds stress and transport barrier physics
journal, May 2000


Core Transport Improvement during Poloidal Current Drive in the RFX Reversed Field Pinch
journal, February 1999


Electron Heat Transport Measured in a Stochastic Magnetic Field
journal, July 2003


Measurement of magnetic fluctuation-induced heat transport in tokamaks and RFP
journal, December 1996


Electron Heat Transport in a Tokamak with Destroyed Magnetic Surfaces
journal, January 1978


Observation of Reduced Heat Transport inside the Magnetic Island O Point in the Large Helical Device
journal, February 2004


Bifurcation to 3D Helical Magnetic Equilibrium in an Axisymmetric Toroidal Device
journal, December 2011


Turbulence spreading into the linearly stable zone and transport scaling
journal, April 2004


Observation of Plasma Flow at the Magnetic Island in the Large Helical Device
journal, December 2001


Reversal of Intrinsic Torque Associated with the Formation of an Internal Transport Barrier
journal, July 2013


Self-Consistent Model of Stochastic Magnetic Fields
journal, August 1980


Observations of secondary structures after collapse events occurring at the q = 2 magnetic surface in the TEXTOR tokamak
journal, August 2007


Active Control of Type-I Edge-Localized Modes with n = 1 Perturbation Fields in the JET Tokamak
journal, June 2007


The role of stochasticity in sawtooth oscillations
journal, March 1992


Plasmoid-induced-reconnection and fractal reconnection
journal, June 2001

  • Shibata, Kazunari; Tanuma, Syuniti
  • Earth, Planets and Space, Vol. 53, Issue 6
  • DOI: 10.1186/BF03353258

Fast transport changes and power degradation in the W7-AS stellarator
journal, July 1996


Some effects of MHD activity on impurity transport in the PBX tokamak
report, October 1985


Nonlinear coupling of tearing modes with self-consistent resistivity evolution in tokamaks
report, February 1980


Forced Magnetic Reconnection
journal, January 1982


Plasmoid-Induced-Reconnection and Fractal Reconnection
text, January 2001


Works referencing / citing this record:

Nonlinear dynamics of turbulence driven magnetic islands. II. Numerical simulations
journal, April 2017

  • Agullo, O.; Muraglia, M.; Benkadda, S.
  • Physics of Plasmas, Vol. 24, Issue 4
  • DOI: 10.1063/1.4981230