| Project/Area Number |
17540469
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plasma science
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| Research Institution | Kyoto University |
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Principal Investigator |
TANAKA Hitoshi Kyoto Univ., Energy Science, Associate Professor, エネルギー科学研究科, 助教授 (90183863)
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| Co-Investigator(Kenkyū-buntansha) |
MAEKAWA Takashi Kyoto Univ., Energy Science, Professor, エネルギー科学研究科, 教授 (20127137)
UCHIDA Masaki Kyoto Univ., Energy Science, Assistant, エネルギー科学研究科, 助手 (90322164)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | magnetic reconnection / spontaneous formation of magnetic surfaces / electron cyclotron heating / current start-up / spherical tokamak |
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| Research Abstract |
Magnetic reconnection is observed in solar flares, magnetosphere and tokamak plasmas, and is widely known as a dynamical and general phenomenon involved with electromagnetic field and plasmas. So far, many experiments and observations as well as theoretical investigations are devoted to explain the physical mechanism but many questions still remain unresolved.
We discovered at the first time that toroidal plasma current increased rapidly ("current jump") when an electron cyclotron resonance torus plasma was produced under a weak steady vertical magnetic field in the LATE device, and observed that the magnetic filed topology was changed during the current jump from open field configuration to closed one spontaneously, i.e., under the constant external conditions.
It was shown that the current jump occurred under the wide vertical field strength from 7 to 85 G, changing the injected microwave power from 1 to 130 kW and microwave frequencies as 2.45 and 5 GHz. Using magnetic measurements, h
… More
ard X-ray pulse height analysis with CdTe semiconductor detectors, soft X-ray CT and fast CCD camera, it was found that the toroidal current was generated and increased rapidly by mode-converted electron Bernstein wave heating and anisotropic confinement property of electrons, and the self-produced poloidal field caused reconnection of magnetic field lines. The characteristics of toroidal MHD equilibrium also changes from the pressure-ballooning-force-dominant to the current-loop-force-dominant.
A movable electrostatic ion detector/electrical probe was attached to the upper wall of LATE to detect the plasma flow along the open field lines during the current jump. Time evolution and spatial distribution of ion saturation current were obtained by changing the position of the detector shot by shot. It was observed that the ion saturation current increased severalfold during the current jump locally, which may be caused by the plasma flow accelerated along the field lines during the reconnection. Less
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