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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.

Authors:
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  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Local linear gyrokinetic simulations NSTX
Keywords:
Local linear gyrokinetic simulations NSTX
OSTI Identifier:
1367078
DOI:
https://doi.org/10.11578/1367078

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:https://doi.org/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:https://doi.org/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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