Effects of collisional ion-orbit loss on neoclassical tokamak radial electric fields

ORAL

Abstract

Ion-orbit loss is considered important to the radial electric fields Er of tokamak edge plasmas. In neoclassical equilibria, collisions can scatter ions onto the loss orbits and generate a steady-state radial current, which may drive the edge Er away from its neoclassical value. To quantitatively measure this effect, an ion-orbit-flux diagnostic [1,2] has been implemented in the axisymmetric version of the gyrokinetic particle-in-cell code XGC [3]. The validity of the diagnostic is demonstrated by studying the collisional relaxation of Er in the core plasmas. Then, the ion orbit-loss effect is numerically measured at the edge for an H-mode plasma in the DIII-D geometry. It is found that the steady-state collisional ion orbit loss is not significant enough to drive Er away from its neoclassical value with the given plasma parameters.

*This work was supported by the U.S. Department of Energy through Contract No. DE-AC02–09CH11466. The simulations presented in this article were performed on computational resources managed and supported by Princeton Research Computing, a consortium of groups including the Princeton Institute for Computational Science and Engineering (PICSciE) and the Office of Information Technology's High Performance Computing Center and Visualization Laboratory at Princeton University. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

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Publication: [1] T. Stoltzfus-Dueck, Nuclear Fusion 60, 016031 (2020).
[2] T. Stoltzfus-Dueck and H. Zhu, submitted to Plasma Physics and Controlled Fusion.
[3]. See https://www.osti.gov/doecode/biblio/12570 for details about the code XGC.

Presenters

  • Hongxuan Zhu

    • Princeton Plasma Physics Laboratory

Authors

  • Hongxuan Zhu

    • Princeton Plasma Physics Laboratory

  • Timothy J Stoltzfus-Dueck

    • Princeton University
    • Princeton Plasma Physics Laboratory

  • Robert Hager

    • Princeton Plasma Physics Laboratory

  • Seung Hoe Ku

    • Princeton Plasma Physics Laboratory

  • Choongseok Chang

    • Princeton Plasma Physics Laboratory
    • Princeton Plasma Physics Laboratory, Princeton University