Optimal control of the plasma azimuthal velocity profile by feedback E× B actuation in HELCAT

Zeki Okan Ilhan, David Huxley-Cohen, Hexiang Wang, Eugenio Schuster, Mark Gilmore, Andrew Ware

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Active control of the flow shear, which is related to the radial derivative of the azimuthal flow, is a key factor in reducing the cross-field turbulence-driven particle transport in a magnetically confined plasma column. Once a desired radial azimuthal velocity profile and its associated level of turbulent fluctuations are identified, the challenge of systematically achieving and sustaining it still remains. In this paper, a model-based feedback controller is proposed to overcome this challenge in helicon-cathode (HELCAT). This linear, dual-source, magnetized-plasma, laboratory device employs concentric ring electrodes to mitigate the turbulent plasma transport by generating a sheared radial electric field and modifying the flow profiles by E×B actuation. A linear-quadratic-integral optimal feedback controller is designed to minimize a weighted combination of the tracking error and the control effort with an ultimate goal of regulating the radial azimuthal velocity profile around a prescribed desired profile even with external disturbances and perturbed initial conditions. Numerical simulations show the effectiveness of the proposed controller in shaping the azimuthal flow profile in HELCAT. The proposed control solution has the potential of being used as a systematic tool for physics-oriented studies in laboratory plasmas such as those achieved in HELCAT.

    Original languageEnglish
    Article number6750102
    Pages (from-to)469-476
    Number of pages8
    JournalIEEE Transactions on Plasma Science
    Volume42
    Issue number3
    DOIs
    StatePublished - Mar 2014

    Keywords

    • Azimuthal velocity profile control
    • optimal linear-quadratic-integral feedback control
    • plasma transport control

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