| Co-Investigator(Kenkyū-buntansha) |
NIHIURA Masaki Nat.Ins., Fusion Sci., Res.Asso., 核融合科学研究所, 助手 (60360616)
KITAJIMA Sumio Tohoku University, Graduate Sch.of Engineering, Asso.Prof., 大学院・工学研究科, 助教授 (30161475)
SHINTO Katsuhiro Tohoku University, Graduate School of Science, Res.Asso., 大学院・理学研究科, 助手 (80322999)
WADA Motoi Doshisha University, Faculty of Eng., Prof., 工学部, 教授 (30201263)
TAKAYAMA Masakazu Akita Prefectual University, Faculty of Systems Science and Technology, Asso.Prof., システム科学技術学部, 助教授 (20236368)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2002: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
In fusion devices, surfaces of limiter and diverter materials are continuously bombarded by electrons, ions, alpha particles, and neutral particles. These surfaces are changing time-to-time, and different from a clean material surface. Surface interactions of energetic particles, such as reflection, sputtering, desorption, etc., play significant roles not only for the plasma facing components but also for the plasma performance. The surface interactions on divertor plates are one of the major concerns in the aspects of the wall life time and heat removal, and these issues are fundamentally connected to the particle recycling from the diverter wall and the plasma-surface interaction in. High-Z materials, such as molybdenum or Tungsten are now attracting attention from these aspects, but the property of their-composite surfaces, or surfaces with coverage of other materials in the vacuum vessel, such as carbon, has not yet been studied enough. We have developed an experimental system to study low energy beam interaction with materials systematically. The angular distributions and energy spectra of reflected positive and negative ions from molybdenum and carbon-evaporated molybdenum surfaces bombarded by low energy (0.5-3 keV) ion-and neutral -particle-beams of hydrogen, H^+,H_2^+,H^O are measured. The angular distributions, energy spectra and the ratio of negative to positive ions due to molecular hydrogen ions bombardment. are nearly equal to those due to proton incidence of same velocity. The negative ion fraction from a carbon-evaporated surface is suppressed in most of cases, especially in the beginning of the bombardment.
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