2004 Fiscal Year Final Research Report Summary
Study on neutral particle behavior in non-axisymmetric minimum-B region of a tandem mirror
| Project/Area Number |
15540467
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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 | University of Tsukuba |
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Principal Investigator |
NAKASHIMA Yousuke University of Tsukuba, Graduate School of Pure and Applied Sciences, Associate Professor, 大学院・数理物質科学研究科, 助教授 (00188939)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIKAWA Masayuki University of Tsukuba, Graduate School of Pure and Applied Sciences, Assistant Professor, 大学院・数理物質科学研究科, 講師 (00272138)
SHOJI Mamoru University of Tsukuba, National Institute for Fusion Science, National Institutes for Natural Sciences, Research Associate, 核融合科学研究所, 助手 (00280602)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Tandem Mirror / Neutral Hydrogen Atoms and Molecules / H-Alpha Line-emission Measurement / Non-axisymmetric Structure / Monte-Carlo Simulation / DEGAS Code |
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| Research Abstract |
The objective of this research is to measure he Hydrogen Balmer-alpha(Hα) line emission from the anchor cell and from the transition region in the anchor minimum-B region. We also performed a neutral transport simulation using a Monte-Carlo code "DEGAS". In this simulation, the density and temperature profiles of hydrogen atoms and molecules are predicted in non-axismmetric anchor mirror cell and hence a important knowledge with particle transport in such complicated configuration of this magnetic structure.
In the last fiscal year, a newly designed two-dimensional Hα detector array was constructed. In order to measure the line emission from the narrow viewing area, the detector was required to obtain a high spatial resolution and its characteristics of the detector were investigated by using a standard lamp. A three-dimensional Monte-Carlo neutral particle simulation code "DEGAS ver.63" was applied to the GAMMA 10 anchor cell for the first time and a simulation study in this region was
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started. A preliminary mesh model was constructed and three-dimensional simulation was carried out. From this simulation, it was found that two particle sources (mirror throat gas puffer and a limiter at the outer transition region of the anchor cell) successfully explain the measured results of Hα line-emission in the anchor cell.
In this fiscal year, the first measurement of detailed structure of the Hα line-emission in the anchor outer-transition region was successfully performed using the above detector array. It was found that the measured Hα line intensity has a strong peak along the miner axis of elliptically elongated plasma cross-section. On the contrary, in an axial direction along the magnetic field line, the spatial profile of the line intensity became flat. In order to explain the obtained results, a new mesh model covering from the anchor cell to the plug/barrier cell was constructed and detailed simulation based on the realistic structure of these cells was performed. The simulation results considering a particle source from the limiter at this region showed a good agreement with the measured profiles. A unified mesh mode covering from the central-cell to the anchor-cell was successfully built up, which enabled to precisely simulate the neutral transport in the connecting region between the two cells efficiently. From the above results, the three-dimensional structure of plasma and vacuum chamber wall plays an important roll in neutral transport in this region. Less
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Research Products
(15 results)
