Observation of Anti-E×B Tripole Vortex in a Plasma

M. Y. Tanaka, A. Okamoto, K. Nagaoka, S. Yosimura, J. Vranjes, M. Kono

    Research output: Contribution to journalArticle

    Abstract

    Flow velocity field of ions has been measured in a magnetized cylindrical plasma, and the vorticity distribution on a plane perpendicular to the magnetic field has been determined to identify vortex formation. A tripole vortex, which consists of three aligned vortices with alternate signs of polarity of rotation, has been observed for the first time. The most important fact on the tripole vortex is that each vortex rotates in the direction opposite to the E×B drift. This means the existence of another force acting on ions, which overcomes the radial electric field. We have confirmed that there always presents a deep density hole in the background neutrals when the tripole vortex is generated, and that the scale of tripole vortex is closely related to the scale of neutral density hole. It is also found that the inward flow of neutrals induced by its steep density gradient is converted into ions through charge exchange interaction. In this process, a net momentum transport takes place, resulting in generation of an effective force acting on ion fluid. Since the direction of effective force is opposite to the radial electric field, it may drive the plasma into anti-E×B rotation, dominating the radial electric field. The vorticity distribution of ion flow field is determined by∇2 lognn in this case, where nn is the density profile of background neutrals. The quantity log nn becomes stream function instead of electrostatic potential. We have experimentally confirmed that the two-dimensional distribution of ∇2 log nn well agrees with that of ω = rot u. The observed tripole vortex is considered to be a vortex structure generated in the coupled system of plasma and flow of neutrals.

    Original languageEnglish
    Number of pages1
    JournalIEEE International Conference on Plasma Science
    Publication statusPublished - 2003

    Fingerprint

    Vortex flow
    vortices
    Plasmas
    Ions
    Electric fields
    Vorticity
    vorticity
    electric fields
    ions
    cylindrical plasmas
    ion charge
    Exchange interactions
    charge exchange
    Flow velocity
    Electrostatics
    Flow fields
    polarity
    Momentum
    flow distribution
    flow velocity

    All Science Journal Classification (ASJC) codes

    • Atomic and Molecular Physics, and Optics
    • Condensed Matter Physics
    • Electrical and Electronic Engineering

    Cite this

    Tanaka, M. Y., Okamoto, A., Nagaoka, K., Yosimura, S., Vranjes, J., & Kono, M. (2003). Observation of Anti-E×B Tripole Vortex in a Plasma. IEEE International Conference on Plasma Science.

    Observation of Anti-E×B Tripole Vortex in a Plasma. / Tanaka, M. Y.; Okamoto, A.; Nagaoka, K.; Yosimura, S.; Vranjes, J.; Kono, M.

    In: IEEE International Conference on Plasma Science, 2003.

    Research output: Contribution to journalArticle

    Tanaka, MY, Okamoto, A, Nagaoka, K, Yosimura, S, Vranjes, J & Kono, M 2003, 'Observation of Anti-E×B Tripole Vortex in a Plasma', IEEE International Conference on Plasma Science.
    Tanaka MY, Okamoto A, Nagaoka K, Yosimura S, Vranjes J, Kono M. Observation of Anti-E×B Tripole Vortex in a Plasma. IEEE International Conference on Plasma Science. 2003.
    Tanaka, M. Y. ; Okamoto, A. ; Nagaoka, K. ; Yosimura, S. ; Vranjes, J. ; Kono, M. / Observation of Anti-E×B Tripole Vortex in a Plasma. In: IEEE International Conference on Plasma Science. 2003.
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