Flow characteristics of a cold helium arc-jet plasma along open field lines

Authors

  • Kazuyuki Yoshida,

    Member, Corresponding author
    1. Department of Energy Sciences, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo 152-8550, Japan
    • Department of Energy Sciences, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo 152-8550, Japan
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  • Toshiaki Kanuma,

    Non-member
    1. Department of Energy Sciences, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo 152-8550, Japan
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  • Hiroki Ichii,

    Non-member
    1. Department of Energy Sciences, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo 152-8550, Japan
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  • Atsushi Nezu,

    Non-member
    1. Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo152-8550, Japan
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  • Haruaki Matsuura,

    Non-member
    1. Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo152-8550, Japan
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  • Hiroshi Akatsuka

    Member
    1. Department of Energy Sciences, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo 152-8550, Japan
    2. Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-10 O-Okayama Meguro-ku, Tokyo152-8550, Japan
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Abstract

We experimentally study plasma parameters including ion acoustic Mach number of expanding cold helium plasma jet with an electron temperature of less than 1 eV flowing along open field lines. It is experimentally found that the ion Mach number increases from 1 to 3, and that the plasma potential decreases by about 1 V. We discuss the experimental results based on a quasi one-dimensional flow model in which the plasma is assumed to be quasi-neutral and in a state of thermodynamic equilibrium. Our model describes the ion acceleration, the axial profiles of the potential drop, and the electron temperature/density. The model also shows that the helium ions are accelerated both by the electric field and by the increasing cross-sectional area of the transonic flow. After the ion acceleration, the ion Mach number decreases and the electron temperature increases. These phenomena are discussed in terms of a shock wave. It is noted that the electron density decreases even in the shock wave. This is discussed in terms of rapid recombination because of the low electron temperature. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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