Turbulence trigger for neoclassical tearing modes in tokamaks

Sanae I. Itoh, Kimitaka Itoh, Masatoshi Yagi

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

A stochastic trigger by micro-turbulence for neoclassical tearing modes (NTMs) is studied. NTMs induce topological change of magnetic structure and have a subcritical nature. It is found that the NTM can be excited regardless of the presence of seed islands. The transition rate of the NTM, its probability density function and its statistically averaged amplitude are obtained. The boundary in the phase diagram is determined as the statistical long time average of the transition conditions. The NTM can be excited by crossing this boundary even in the absence of other global instabilities. The boundary is expressed in terms of the poloidal beta value. Its dependence on the ratio between the ion banana width and radius of the rational surface, ρb/rs, is found to vary in the range ρ b/rs-(ρb/rs)2, depending on the linear stability of the tearing mode.

Original languageEnglish
Pages (from-to)123-143
Number of pages21
JournalPlasma Physics and Controlled Fusion
Volume46
Issue number1
DOIs
Publication statusPublished - Jan 1 2004

Fingerprint

Turbulence
actuators
turbulence
Magnetic structure
Probability density function
Phase diagrams
Seed
Ions
probability density functions
seeds
phase diagrams
radii
ions

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Turbulence trigger for neoclassical tearing modes in tokamaks. / Itoh, Sanae I.; Itoh, Kimitaka; Yagi, Masatoshi.

In: Plasma Physics and Controlled Fusion, Vol. 46, No. 1, 01.01.2004, p. 123-143.

Research output: Contribution to journalArticle

Itoh, Sanae I. ; Itoh, Kimitaka ; Yagi, Masatoshi. / Turbulence trigger for neoclassical tearing modes in tokamaks. In: Plasma Physics and Controlled Fusion. 2004 ; Vol. 46, No. 1. pp. 123-143.
@article{2f157d0b57ad428f8fd24a7b0fb74317,
title = "Turbulence trigger for neoclassical tearing modes in tokamaks",
abstract = "A stochastic trigger by micro-turbulence for neoclassical tearing modes (NTMs) is studied. NTMs induce topological change of magnetic structure and have a subcritical nature. It is found that the NTM can be excited regardless of the presence of seed islands. The transition rate of the NTM, its probability density function and its statistically averaged amplitude are obtained. The boundary in the phase diagram is determined as the statistical long time average of the transition conditions. The NTM can be excited by crossing this boundary even in the absence of other global instabilities. The boundary is expressed in terms of the poloidal beta value. Its dependence on the ratio between the ion banana width and radius of the rational surface, ρb/rs, is found to vary in the range ρ b/rs-(ρb/rs)2, depending on the linear stability of the tearing mode.",
author = "Itoh, {Sanae I.} and Kimitaka Itoh and Masatoshi Yagi",
year = "2004",
month = "1",
day = "1",
doi = "10.1088/0741-3335/46/1/008",
language = "English",
volume = "46",
pages = "123--143",
journal = "Plasma Physics and Controlled Fusion",
issn = "0741-3335",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - Turbulence trigger for neoclassical tearing modes in tokamaks

AU - Itoh, Sanae I.

AU - Itoh, Kimitaka

AU - Yagi, Masatoshi

PY - 2004/1/1

Y1 - 2004/1/1

N2 - A stochastic trigger by micro-turbulence for neoclassical tearing modes (NTMs) is studied. NTMs induce topological change of magnetic structure and have a subcritical nature. It is found that the NTM can be excited regardless of the presence of seed islands. The transition rate of the NTM, its probability density function and its statistically averaged amplitude are obtained. The boundary in the phase diagram is determined as the statistical long time average of the transition conditions. The NTM can be excited by crossing this boundary even in the absence of other global instabilities. The boundary is expressed in terms of the poloidal beta value. Its dependence on the ratio between the ion banana width and radius of the rational surface, ρb/rs, is found to vary in the range ρ b/rs-(ρb/rs)2, depending on the linear stability of the tearing mode.

AB - A stochastic trigger by micro-turbulence for neoclassical tearing modes (NTMs) is studied. NTMs induce topological change of magnetic structure and have a subcritical nature. It is found that the NTM can be excited regardless of the presence of seed islands. The transition rate of the NTM, its probability density function and its statistically averaged amplitude are obtained. The boundary in the phase diagram is determined as the statistical long time average of the transition conditions. The NTM can be excited by crossing this boundary even in the absence of other global instabilities. The boundary is expressed in terms of the poloidal beta value. Its dependence on the ratio between the ion banana width and radius of the rational surface, ρb/rs, is found to vary in the range ρ b/rs-(ρb/rs)2, depending on the linear stability of the tearing mode.

UR - http://www.scopus.com/inward/record.url?scp=0942299118&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0942299118&partnerID=8YFLogxK

U2 - 10.1088/0741-3335/46/1/008

DO - 10.1088/0741-3335/46/1/008

M3 - Article

AN - SCOPUS:0942299118

VL - 46

SP - 123

EP - 143

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

SN - 0741-3335

IS - 1

ER -