Direct measurement of energetic electron flow in Q-shu University experiment with steady-state spherical tokamak

Journal Article · Tue Nov 15 00:00:00 EST 2011 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3662204· OSTI ID:22063748

Ishiguro, Masaki; Haiqing, Liu; Tokunaga, Tomonori; Tashima, Saya ^[1]; Hanada, Kazuaki; Zushi, Hideki; Yoshida, Naoaki; Nakamura, Kazuo; Fujisawa, Akihide; Idei, Hiroshi; Sakamoto, Mizuki; Hasegawa, Makoto; Kawasaki, Shoji; Nakashima, Hisatoshi; Higashijima, Aki ^[2]; Takase, Yuichi ^[3]; Maekawa, Takashi; Kishimoto, Yasuaki ^[4]; Mitarai, Osamu ^[5]

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1. Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816-8580 (Japan)
2. Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan)
3. Graduate School of Frontier Science, University Tokyo, Kashiwa 277-8561 (Japan)
4. Graduate School of Energy Science, Kyoto University, Kyoto 606-8502 (Japan)
5. Liberal Arts Education Center, Kumamoto Campus, Tokai University, 9-1-1 Toroku, Kumamoto 862-8652 (Japan)

In magnetized plasmas, the presence of a significant number of energetic electrons has been observed but quantitative characteristics of these electrons are proving difficult to investigate. A Langmuir probe offers a means to provide quantitative measurement of these energetic electrons that takes into account electron emissions (secondary electron emission and electron reflection) from the probe tips and sheath expansion around the probe tips caused by a considerable negative potential. In this paper, these effects are experimentally confirmed and an analytical means to measure energetic electron characteristics are proposed. An analysis of plasmas produced by a high frequency wave is then applied leading to the successful detection of an asymmetric flow of energetic electrons. The estimated electron temperature and current density were approximately 4-5 keV and 2-3 kA/m{sup 2}.

• OSTI ID: 22063748
• Journal Information: Review of Scientific Instruments, Vol. 82, Issue 11; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
CURRENT DENSITY
ELECTRON DETECTION
ELECTRON EMISSION
ELECTRON TEMPERATURE
KEV RANGE
LANGMUIR PROBE
PLASMA
PLASMA EXPANSION
PLASMA PRODUCTION
PLASMA SHEATH
REFLECTION
SPHERICAL CONFIGURATION
STEADY-STATE CONDITIONS
TAIL ELECTRONS
TOKAMAK DEVICES