Self-sustained annihilation of magnetic islands in helical plasmas

Kimitaka Itoh; Sanae I. Itoh; Masatoshi Yagi

doi:10.1063/1.1946731

Self-sustained annihilation of magnetic islands in helical plasmas

Kimitaka Itoh, Sanae I. Itoh, Masatoshi Yagi

Division of Nuclear Fusion Dynamics

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

8 Citations (Scopus)

Abstract

The evolution of the magnetic island which is induced by the resonant deformation by external currents in helical systems (such as the large helical device (LHD) [A. Iiyoshi, Phys. Plasmas 2, 2349 (1995)]) is analyzed. The defect of the bootstrap current, caused by the magnetic island, has a parity which reduces the size of the magnetic island, if the bootstrap current enhances the vacuum rotational transform. The width of magnetic island can be suppressed to the level of ion banana width if the pressure gradient exceeds a threshold value. This island annihilation is self-sustained. That is, the annihilation continues, for fixed beta value, until the external drive for island generation exceeds a threshold. The effects of the reversal of the direction of the bootstrap current and of the sign of radial electric field are also investigated. The possibility of the neoclassical tearing mode in the LHD-like plasma is discussed.

Original language	English
Pages (from-to)	1-6
Number of pages	6
Journal	Physics of Plasmas
Volume	12
Issue number	7
DOIs	https://doi.org/10.1063/1.1946731
Publication status	Published - Jul 2005

All Science Journal Classification (ASJC) codes

Condensed Matter Physics

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10.1063/1.1946731

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@article{d50d92df0607409e8d7944fe3f207650,

title = "Self-sustained annihilation of magnetic islands in helical plasmas",

abstract = "The evolution of the magnetic island which is induced by the resonant deformation by external currents in helical systems (such as the large helical device (LHD) [A. Iiyoshi, Phys. Plasmas 2, 2349 (1995)]) is analyzed. The defect of the bootstrap current, caused by the magnetic island, has a parity which reduces the size of the magnetic island, if the bootstrap current enhances the vacuum rotational transform. The width of magnetic island can be suppressed to the level of ion banana width if the pressure gradient exceeds a threshold value. This island annihilation is self-sustained. That is, the annihilation continues, for fixed beta value, until the external drive for island generation exceeds a threshold. The effects of the reversal of the direction of the bootstrap current and of the sign of radial electric field are also investigated. The possibility of the neoclassical tearing mode in the LHD-like plasma is discussed.",

author = "Kimitaka Itoh and Itoh, {Sanae I.} and Masatoshi Yagi",

note = "Funding Information: The authors acknowledge Professor Y. Nagayama, Professor Y. Miura, and Dr. A. Isayama for useful discussions on experimental observations. This work was partly supported by the Grant-in-Aid for Specially-Promoted Research (Grant No. 16002005) and the Grant-in-Aid for Scientific Research (Grant No. 15360495) of Ministry Education, Culture, Sports, Science and Technology of Japan, by the Collaboration Programs of NIFS and of the RIAM of Kyushu University.",

year = "2005",

month = jul,

doi = "10.1063/1.1946731",

language = "English",

volume = "12",

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journal = "Physics of Plasmas",

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T1 - Self-sustained annihilation of magnetic islands in helical plasmas

AU - Itoh, Kimitaka

AU - Itoh, Sanae I.

AU - Yagi, Masatoshi

N1 - Funding Information: The authors acknowledge Professor Y. Nagayama, Professor Y. Miura, and Dr. A. Isayama for useful discussions on experimental observations. This work was partly supported by the Grant-in-Aid for Specially-Promoted Research (Grant No. 16002005) and the Grant-in-Aid for Scientific Research (Grant No. 15360495) of Ministry Education, Culture, Sports, Science and Technology of Japan, by the Collaboration Programs of NIFS and of the RIAM of Kyushu University.

PY - 2005/7

Y1 - 2005/7

N2 - The evolution of the magnetic island which is induced by the resonant deformation by external currents in helical systems (such as the large helical device (LHD) [A. Iiyoshi, Phys. Plasmas 2, 2349 (1995)]) is analyzed. The defect of the bootstrap current, caused by the magnetic island, has a parity which reduces the size of the magnetic island, if the bootstrap current enhances the vacuum rotational transform. The width of magnetic island can be suppressed to the level of ion banana width if the pressure gradient exceeds a threshold value. This island annihilation is self-sustained. That is, the annihilation continues, for fixed beta value, until the external drive for island generation exceeds a threshold. The effects of the reversal of the direction of the bootstrap current and of the sign of radial electric field are also investigated. The possibility of the neoclassical tearing mode in the LHD-like plasma is discussed.

AB - The evolution of the magnetic island which is induced by the resonant deformation by external currents in helical systems (such as the large helical device (LHD) [A. Iiyoshi, Phys. Plasmas 2, 2349 (1995)]) is analyzed. The defect of the bootstrap current, caused by the magnetic island, has a parity which reduces the size of the magnetic island, if the bootstrap current enhances the vacuum rotational transform. The width of magnetic island can be suppressed to the level of ion banana width if the pressure gradient exceeds a threshold value. This island annihilation is self-sustained. That is, the annihilation continues, for fixed beta value, until the external drive for island generation exceeds a threshold. The effects of the reversal of the direction of the bootstrap current and of the sign of radial electric field are also investigated. The possibility of the neoclassical tearing mode in the LHD-like plasma is discussed.

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Self-sustained annihilation of magnetic islands in helical plasmas

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