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Title: Linear gyrokinetic simulations of microinstabilities within the pedestal region of H-mode NSTX discharges in a highly shaped geometry

Abstract

Linear (local) gyrokinetic predictions of edge microinstabilities in highly shaped, lithiated and non-lihiated NSTX discharges are reported using the gyrokinetic code GS2. Microtearing modes dominate the non-lithiated pedestal top. The stabilization of these modes at the lithiated pedestal top enables the electron temperature pedestal to extend further inwards, as observed experimentally. Kinetic ballooning modes are found to be unstable mainly at the mid-pedestal of both types of discharges, with unstable trapped electron modes nearer the separatrix region. At electron wavelengths, ETG modes are found to be unstable from mid-pedestal outwards for eta(e,exp)~2.2, with higher growth rates for the lithiated discharge. Near the separatrix, the critical temperature gradient for driving ETG modes is reduced in the presence of lithium, reflecting the reduction of the lithiated density gradients observed experimentally. A preliminary linear study in the edge of non-lithiated discharges shows that the equilibrium shaping alters the electrostatic modes stability, found more unstable at high plasma shaping.


Citation Formats

Coury, M., Guttenfelder, W., Mikkelsen, D., Canik, J., Canal, G., Diallo, A., Kaye, S., Kramer, G., and Maingi, R. Linear gyrokinetic simulations of microinstabilities within the pedestal region of H-mode NSTX discharges in a highly shaped geometry. United States: N. p., 2016. Web. doi:10.11578/1367078.
Coury, M., Guttenfelder, W., Mikkelsen, D., Canik, J., Canal, G., Diallo, A., Kaye, S., Kramer, G., & Maingi, R. Linear gyrokinetic simulations of microinstabilities within the pedestal region of H-mode NSTX discharges in a highly shaped geometry. United States. doi:10.11578/1367078.
Coury, M., Guttenfelder, W., Mikkelsen, D., Canik, J., Canal, G., Diallo, A., Kaye, S., Kramer, G., and Maingi, R. 2016. "Linear gyrokinetic simulations of microinstabilities within the pedestal region of H-mode NSTX discharges in a highly shaped geometry". United States. doi:10.11578/1367078. https://www.osti.gov/servlets/purl/1367078. Pub date:Wed Jun 01 00:00:00 EDT 2016
@article{osti_1367078,
title = {Linear gyrokinetic simulations of microinstabilities within the pedestal region of H-mode NSTX discharges in a highly shaped geometry},
author = {Coury, M. and Guttenfelder, W. and Mikkelsen, D. and Canik, J. and Canal, G. and Diallo, A. and Kaye, S. and Kramer, G. and Maingi, R.},
abstractNote = {Linear (local) gyrokinetic predictions of edge microinstabilities in highly shaped, lithiated and non-lihiated NSTX discharges are reported using the gyrokinetic code GS2. Microtearing modes dominate the non-lithiated pedestal top. The stabilization of these modes at the lithiated pedestal top enables the electron temperature pedestal to extend further inwards, as observed experimentally. Kinetic ballooning modes are found to be unstable mainly at the mid-pedestal of both types of discharges, with unstable trapped electron modes nearer the separatrix region. At electron wavelengths, ETG modes are found to be unstable from mid-pedestal outwards for eta(e,exp)~2.2, with higher growth rates for the lithiated discharge. Near the separatrix, the critical temperature gradient for driving ETG modes is reduced in the presence of lithium, reflecting the reduction of the lithiated density gradients observed experimentally. A preliminary linear study in the edge of non-lithiated discharges shows that the equilibrium shaping alters the electrostatic modes stability, found more unstable at high plasma shaping.},
doi = {10.11578/1367078},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2016},
month = {6}
}

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Works referenced in this record:

Linear gyrokinetic simulations of microinstabilities within the pedestal region of H-mode NSTX discharges in a highly shaped geometry
journal, June 2016

  • Coury, M.; Guttenfelder, W.; Mikkelsen, D. R.
  • Physics of Plasmas, Vol. 23, Issue 6
  • DOI: 10.1063/1.4954911

    Works referencing / citing this record:

    Linear gyrokinetic simulations of microinstabilities within the pedestal region of H-mode NSTX discharges in a highly shaped geometry
    journal, June 2016

    • Coury, M.; Guttenfelder, W.; Mikkelsen, D. R.
    • Physics of Plasmas, Vol. 23, Issue 6
    • DOI: 10.1063/1.4954911