Parametric study of two-dimensional potential structures induced by radio-frequency sheaths coupled with transverse currents in front of the Ion Cyclotron Resonance Heating antenna

Faudot, E; Heuraux, S; Colas, L

doi:10.1063/1.2186530

Title: Parametric study of two-dimensional potential structures induced by radio-frequency sheaths coupled with transverse currents in front of the Ion Cyclotron Resonance Heating antenna

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Abstract

For the first time, a two-dimensional (2D) fluid model and an analytical expression for the rectified potential with respect to the transverse polarization current are established and verified by a 2D PIC (particle in cell) code over the validity domain of our model. Then the model is extended to the overall ion cyclotron frequency range used in different heating and current drive scenarios. First, the models demonstrate that these transverse polarization currents add some inertia in the temporal dynamic. Due to the nonlinear behavior of the I-V sheath characteristic, the time average amplitude (dc potential) of the rectified potential structure is increased compared to the time average rf potential. Second, they induce only a slight widening of the potential structure. Such modifications are quantified using a 'test map' initially characterized by a Gaussian shape. The map is assumed to remain Gaussian near its summit. The time behavior of the peak can be estimated analytically in the presence of polarization current as a function of its width r{sub 0} and amplitude {phi}{sub 0} (normalized to local temperature and to a characteristic length for transverse transport). A potential peaking criterion has been built to determine the peaking zone of the dc potentialmore »« less

Authors:

Faudot, E; Heuraux, S; Colas, L ^[1]

LPMIA, UMR CNRS 7040, Universite Henri Poincare, Nancy 1, BP 239, 54506 Vandoeuvre Cedex (France)

Publication Date:: Sat Apr 15 00:00:00 EDT 2006

OSTI Identifier:: 20782748

Resource Type:: Journal Article

Journal Name:: Physics of Plasmas

Additional Journal Information:: Journal Volume: 13; Journal Issue: 4; Other Information: DOI: 10.1063/1.2186530; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; ANTENNAS; BOUNDARY LAYERS; CYCLOTRON FREQUENCY; ELECTRIC CURRENTS; HOT SPOTS; ICR HEATING; MOMENT OF INERTIA; NONLINEAR PROBLEMS; PARAMETRIC ANALYSIS; PLASMA; PLASMA CONFINEMENT; PLASMA POTENTIAL; PLASMA SHEATH; PLASMA SIMULATION; POLARIZATION; RADIATION TRANSPORT; RADIOWAVE RADIATION; RF SYSTEMS; TAIL IONS; TORE SUPRA TOKAMAK; TWO-DIMENSIONAL CALCULATIONS

Citation Formats


                    Faudot, E, Heuraux, S, Colas, L, and Association Euratom-CEA pour la fusion Controlee, CEA Cadarache, Saint-Paul-lez-Durance Cedex. Parametric study of two-dimensional potential structures induced by radio-frequency sheaths coupled with transverse currents in front of the Ion Cyclotron Resonance Heating antenna.  United States: N. p., 2006. 
        Web.  doi:10.1063/1.2186530.

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                    Faudot, E, Heuraux, S, Colas, L, & Association Euratom-CEA pour la fusion Controlee, CEA Cadarache, Saint-Paul-lez-Durance Cedex. Parametric study of two-dimensional potential structures induced by radio-frequency sheaths coupled with transverse currents in front of the Ion Cyclotron Resonance Heating antenna.  United States.  https://doi.org/10.1063/1.2186530

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                    Faudot, E, Heuraux, S, Colas, L, and Association Euratom-CEA pour la fusion Controlee, CEA Cadarache, Saint-Paul-lez-Durance Cedex. 2006.  
        "Parametric study of two-dimensional potential structures induced by radio-frequency sheaths coupled with transverse currents in front of the Ion Cyclotron Resonance Heating antenna".  United States.  https://doi.org/10.1063/1.2186530.

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@article{osti_20782748,

  title        = {Parametric study of two-dimensional potential structures induced by radio-frequency sheaths coupled with transverse currents in front of the Ion Cyclotron Resonance Heating antenna},

  author       = {Faudot, E and Heuraux, S and Colas, L and Association Euratom-CEA pour la fusion Controlee, CEA Cadarache, Saint-Paul-lez-Durance Cedex},

  abstractNote = {For the first time, a two-dimensional (2D) fluid model and an analytical expression for the rectified potential with respect to the transverse polarization current are established and verified by a 2D PIC (particle in cell) code over the validity domain of our model. Then the model is extended to the overall ion cyclotron frequency range used in different heating and current drive scenarios. First, the models demonstrate that these transverse polarization currents add some inertia in the temporal dynamic. Due to the nonlinear behavior of the I-V sheath characteristic, the time average amplitude (dc potential) of the rectified potential structure is increased compared to the time average rf potential. Second, they induce only a slight widening of the potential structure. Such modifications are quantified using a 'test map' initially characterized by a Gaussian shape. The map is assumed to remain Gaussian near its summit. The time behavior of the peak can be estimated analytically in the presence of polarization current as a function of its width r{sub 0} and amplitude {phi}{sub 0} (normalized to local temperature and to a characteristic length for transverse transport). A potential peaking criterion has been built to determine the peaking zone of the dc potential structure induced by the rf field. Computations made for typical parameters of the edge plasma in front of the antenna of the Tokamak Tore Supra show that the dc rectified potential is up to 50% higher than the previous computations neglecting polarization current effects. The weak diffused and high dc potential structures computed can explain the hot spot formation induced by convective cells associated to high energetic ion fluxes on the corners of the Ion Cyclotron Resonance Heating ant0010en.},

  doi          = {10.1063/1.2186530},

  url          = {https://www.osti.gov/biblio/20782748},
  journal      = {Physics of Plasmas},

  issn         = {1070-664X},

  number       = 4,

  volume       = 13,

  place        = {United States},

  year         = {Sat Apr 15 00:00:00 EDT 2006},

  month        = {Sat Apr 15 00:00:00 EDT 2006}

}

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