Turbulence trigger for neoclassical tearing modes in tokamaks

Sanae I. Itoh; Kimitaka Itoh; Masatoshi Yagi

doi:10.1088/0741-3335/46/1/008

Turbulence trigger for neoclassical tearing modes in tokamaks

Sanae I. Itoh, Kimitaka Itoh, Masatoshi Yagi

Division of Nuclear Fusion Dynamics

Research output: Contribution to journal › Article › peer-review

29 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, ρ_b/r_s, is found to vary in the range ρ _b/r_s-(ρ_b/r_s)², depending on the linear stability of the tearing mode.

Original language	English
Pages (from-to)	123-143
Number of pages	21
Journal	Plasma Physics and Controlled Fusion
Volume	46
Issue number	1
DOIs	https://doi.org/10.1088/0741-3335/46/1/008
Publication status	Published - Jan 1 2004

All Science Journal Classification (ASJC) codes

Nuclear Energy and Engineering
Condensed Matter Physics

Access to Document

10.1088/0741-3335/46/1/008

Cite this

@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 = jan,

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

SN - 0741-3335

VL - 46

SP - 123

EP - 143

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

IS - 1

ER -

Turbulence trigger for neoclassical tearing modes in tokamaks

Abstract

All Science Journal Classification (ASJC) codes

Access to Document

Other files and links

Fingerprint

Cite this