Experimental characterization and modeling of non-linear coupling of the LHCD power on Tore Supra

Preynas, M.; Goniche, M.; Hillairet, J.; Litaudon, X.; Ekedahl, A.

doi:10.1063/1.4864577

Title: Experimental characterization and modeling of non-linear coupling of the LHCD power on Tore Supra

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Abstract

To achieve steady state operation on future tokamaks, in particular on ITER, the unique capability of a LHCD system to efficiently drive off-axis non-inductive current is needed. In this context, it is of prime importance to study and master the coupling of LH wave to the core plasma at high power density (tens of MW/m{sup 2}). In some specific conditions, deleterious effects on the LHCD coupling are sometimes observed on Tore Supra. At high power the waves may modify the edge parameters that change the wave coupling properties in a non-linear manner. In this way, dedicated LHCD experiments have been performed using the LHCD system of Tore Supra, composed of two different conceptual designs of launcher: the Fully Active Multijunction (FAM) and the new Passive Active Multijunction (PAM) antennas. A nonlinear interaction between the electron density and the electric field has been characterized in a thin plasma layer in front of the two LHCD antennas. The resulting dependence of the power reflection coefficient with the LHCD power, leading occasionally to trips in the output power, is not predicted by the standard linear theory of the LH wave coupling. Therefore, it is important to investigate and understand the possible origin ofmore »« less

Authors:

Preynas, M. ^[1]; Goniche, M.; Hillairet, J.; Litaudon, X.; Ekedahl, A. ^[2]

Max Planck Institut für Plasmaphysik, EURATOM Association, D-17491 Greifswald (Germany)
CEA, IRFM, F-13108 Saint Paul lez Durance (France)

Publication Date:: Wed Feb 12 00:00:00 EST 2014

OSTI Identifier:: 22263886

Resource Type:: Journal Article

Journal Name:: AIP Conference Proceedings

Additional Journal Information:: Journal Volume: 1580; Journal Issue: 1; Conference: 20. topical conference on radiofrequency power in plasmas, Sorrento (Italy), 25-28 Jun 2013; Other Information: (c) 2014 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X

Country of Publication:: United States

Language:: English

Subject:: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COUPLING; ELECTRIC FIELDS; ELECTRON DENSITY; INTERACTIONS; ITER TOKAMAK; PLASMA DENSITY; PONDEROMOTIVE FORCE; POWER DENSITY; SIMULATION; TORE SUPRA TOKAMAK; WAVE PROPAGATION

Citation Formats


                    Preynas, M., Goniche, M., Hillairet, J., Litaudon, X., and Ekedahl, A. Experimental characterization and modeling of non-linear coupling of the LHCD power on Tore Supra.  United States: N. p., 2014. 
        Web.  doi:10.1063/1.4864577.

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                    Preynas, M., Goniche, M., Hillairet, J., Litaudon, X., & Ekedahl, A. Experimental characterization and modeling of non-linear coupling of the LHCD power on Tore Supra.  United States.  https://doi.org/10.1063/1.4864577

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                    Preynas, M., Goniche, M., Hillairet, J., Litaudon, X., and Ekedahl, A. 2014.  
        "Experimental characterization and modeling of non-linear coupling of the LHCD power on Tore Supra".  United States.  https://doi.org/10.1063/1.4864577.

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@article{osti_22263886,

  title        = {Experimental characterization and modeling of non-linear coupling of the LHCD power on Tore Supra},

  author       = {Preynas, M. and Goniche, M. and Hillairet, J. and Litaudon, X. and Ekedahl, A.},

  abstractNote = {To achieve steady state operation on future tokamaks, in particular on ITER, the unique capability of a LHCD system to efficiently drive off-axis non-inductive current is needed. In this context, it is of prime importance to study and master the coupling of LH wave to the core plasma at high power density (tens of MW/m{sup 2}). In some specific conditions, deleterious effects on the LHCD coupling are sometimes observed on Tore Supra. At high power the waves may modify the edge parameters that change the wave coupling properties in a non-linear manner. In this way, dedicated LHCD experiments have been performed using the LHCD system of Tore Supra, composed of two different conceptual designs of launcher: the Fully Active Multijunction (FAM) and the new Passive Active Multijunction (PAM) antennas. A nonlinear interaction between the electron density and the electric field has been characterized in a thin plasma layer in front of the two LHCD antennas. The resulting dependence of the power reflection coefficient with the LHCD power, leading occasionally to trips in the output power, is not predicted by the standard linear theory of the LH wave coupling. Therefore, it is important to investigate and understand the possible origin of such non-linear effects in order to avoid their possible deleterious consequences. The PICCOLO-2D code, which self-consistently treats the wave propagation in the antenna vicinity and its interaction with the local edge plasma density, is used to simulate Tore Supra discharges. The simulation reproduces very well the occurrence of a non-linear behavior in the coupling observed in the LHCD experiments. The important differences and trends between the FAM and the PAM antennas, especially a larger increase in RC for the FAM, are also reproduced by the PICCOLO-2D simulation. The working hypothesis of the contribution of the ponderomotive effect in the non-linear observations of LHCD coupling is therefore validated through this comprehensive modeling for the first time on the FAM and PAM antennas on Tore Supra.},

  doi          = {10.1063/1.4864577},

  url          = {https://www.osti.gov/biblio/22263886},
  journal      = {AIP Conference Proceedings},

  issn         = {0094-243X},

  number       = 1,

  volume       = 1580,

  place        = {United States},

  year         = {Wed Feb 12 00:00:00 EST 2014},

  month        = {Wed Feb 12 00:00:00 EST 2014}

}

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