ECH plasma experiments on an internal coil device with a high temperature superconductor coil

Yuichi Ogawa, Junji Morikawa, Kotaro Ohkuni, Shigeo Yamakoshi, Takuya Goto, Toshiyuki Mito, Nagato Yanagi, Masataka Iwakuma

Research output: Contribution to journalConference article

Abstract

Self-organization related with relaxation phenomenon is playing an important role in various aspects of magnetic confined plasmas. Recently a relaxation theory including the plasma flow has been developed by Mahajan-Yoshida, and a new relaxation state has been identified. The two-fluid relaxation condition is given by β + (V/VA)2 = const. To study a self-organized structure with strong plasma flow, we have introduced an internal coil device. By inducing a radial electric field with appropriate methods, we could drive a toroidal plasma flow, and confine a high beta plasma in a core region. The internal coil device Mini-RT with a high temperature superconductor(HTS) coil(Rc=0.15m, Ic-50kA) has been constructed. The vacuum chamber is 1 m in diameter and ∼ 0.7 m in height. The magnetic field strength near the internal coil is around 0.1 T, and a radio-frequency wave of 2.45 GHz is applied for the plasma production. We have started ECH plasma experiments with the coil supported mechanically. The electron density, which has a peak near the internal coil, is of order 1016 m-3, reaching the cut-off density of the microwave. While, the electron temperature is of order 10 eV with a broad profile. Estimated energy confinement time is of order 10-(5-6) sec. The levitation experiment of the HTS coil has been carried out. The position of the HTS coil is measured with laser sensors, and is feedback-controlled with the levitation coil current. We have succeeded to levitating the HTS coil during one hour with an accuracy of less than 20 μm. A preliminary experiment for the plasma production at the floating condition of the HTS coil has been initiated. It is affirmed that the levitation system works well and plasma with separatrix configuration is produced.

Original languageEnglish
Pages (from-to)63-70
Number of pages8
JournalFusion Science and Technology
Volume47
DOIs
Publication statusPublished - Jan 1 2005
EventFifh International Conference on Open Magnetic Systems for Plasma Confinement - Novosibirsk, Russian Federation
Duration: Jul 5 2004Jul 9 2004

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High temperature superconductors
high temperature superconductors
coils
Plasma flow
Plasmas
Plasma sources
Experiments
levitation
magnetohydrodynamic flow
Electron temperature
Carrier concentration
Microwaves
Electric fields
Vacuum
Magnetic fields
Feedback
Fluids
Lasers
Sensors
toroidal plasmas

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

Cite this

ECH plasma experiments on an internal coil device with a high temperature superconductor coil. / Ogawa, Yuichi; Morikawa, Junji; Ohkuni, Kotaro; Yamakoshi, Shigeo; Goto, Takuya; Mito, Toshiyuki; Yanagi, Nagato; Iwakuma, Masataka.

In: Fusion Science and Technology, Vol. 47, 01.01.2005, p. 63-70.

Research output: Contribution to journalConference article

Ogawa, Yuichi ; Morikawa, Junji ; Ohkuni, Kotaro ; Yamakoshi, Shigeo ; Goto, Takuya ; Mito, Toshiyuki ; Yanagi, Nagato ; Iwakuma, Masataka. / ECH plasma experiments on an internal coil device with a high temperature superconductor coil. In: Fusion Science and Technology. 2005 ; Vol. 47. pp. 63-70.
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abstract = "Self-organization related with relaxation phenomenon is playing an important role in various aspects of magnetic confined plasmas. Recently a relaxation theory including the plasma flow has been developed by Mahajan-Yoshida, and a new relaxation state has been identified. The two-fluid relaxation condition is given by β + (V/VA)2 = const. To study a self-organized structure with strong plasma flow, we have introduced an internal coil device. By inducing a radial electric field with appropriate methods, we could drive a toroidal plasma flow, and confine a high beta plasma in a core region. The internal coil device Mini-RT with a high temperature superconductor(HTS) coil(Rc=0.15m, Ic-50kA) has been constructed. The vacuum chamber is 1 m in diameter and ∼ 0.7 m in height. The magnetic field strength near the internal coil is around 0.1 T, and a radio-frequency wave of 2.45 GHz is applied for the plasma production. We have started ECH plasma experiments with the coil supported mechanically. The electron density, which has a peak near the internal coil, is of order 1016 m-3, reaching the cut-off density of the microwave. While, the electron temperature is of order 10 eV with a broad profile. Estimated energy confinement time is of order 10-(5-6) sec. The levitation experiment of the HTS coil has been carried out. The position of the HTS coil is measured with laser sensors, and is feedback-controlled with the levitation coil current. We have succeeded to levitating the HTS coil during one hour with an accuracy of less than 20 μm. A preliminary experiment for the plasma production at the floating condition of the HTS coil has been initiated. It is affirmed that the levitation system works well and plasma with separatrix configuration is produced.",
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AU - Ogawa, Yuichi

AU - Morikawa, Junji

AU - Ohkuni, Kotaro

AU - Yamakoshi, Shigeo

AU - Goto, Takuya

AU - Mito, Toshiyuki

AU - Yanagi, Nagato

AU - Iwakuma, Masataka

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