Recent Progress on Toroidal Nonneutral Plasmas Confined on Heliotron Magnetic Surfaces

Journal Article · Mon Mar 30 04:00:00 EDT 2009 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3122291· OSTI ID:21300447

Himura, H; Nakamura, K; Sugimoto, D; Sanpei, A; Masamune, S ^[1]; Isobe, M ^[2]; Sano, F ^[3]

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1. Kyoto Institute of Technology, Department of Electronics, Kyoto 606-8585 (Japan)
2. National Institute for Fusion Sciences, Toki 509-5292 (Japan)
3. Kyoto University, Institute of Advanced Energy, Uji 611-0011 (Japan)

Firstly, non-constant space potential {phi}{sub s} and electron density n{sub e} on magnetic surfaces of helical nonneutral plasmas are observed in CHS experiments. The variation of {phi}{sub s} has grown with increasing electron injection energy, implying that thermal effects are important when considering the force balance along magnetic field lines. These observations confirm the existence of plasma equilibrium having non-constant {phi}{sub s} and n{sub e} on magnetic surfaces of helical nonneutral plasmas. Secondly, outward orbits that extend to inward part of closed helical vacuum magnetic region are found in three dimensional calculations which take into account two experimental findings. The pitch angle of electron injected into the stochastic magnetic region is scattered considerably due to the presence of shifted self space potential {phi}{sub s}. Eventually, the injected electron turns to be a helically trapped particle, and start an inward movement along one of the |B{sub min}| contours. Once penetrating deeply, the electron can never escape from the last closed flux surface because the negative {phi}{sub s} acts as a potential barrier. Thirdly, first data obtained from toroidal nonneutral plasmas confined on the quasi-poloidally symmetric magnetic surfaces having a helical-axis is described. It shows that externally produced plasmas are successfully observed, and moreover, the non-constant {phi}{sub s} and n{sub e} of helical nonneutral plasmas are ensured in the Heliotron J experiments, as well.

• OSTI ID: 21300447
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1114; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CHS TORSATRON
ELECTRON BEAM INJECTION
ELECTRON DENSITY
ELECTRONS
HELIOTRON
MAGNETIC FIELDS
MAGNETIC SURFACES
MAGNETISM
PLASMA
PLASMA CONFINEMENT
POTENTIALS
STOCHASTIC PROCESSES
TEMPERATURE DEPENDENCE
TRAPPING