Discontinuous Galerkin methods, positivity, exponential reconstruction, and initial simulations of gyrokinetic turbulence in a model tokamak scrape-off-layer

Greg Hammett

Princeton Plasma Physics Laboratory

Friday, April 6, 2018

3:00pm

NW17-218

PSFC Seminars

We describe the development of the Gkeyll code to carry out 3d2v full-F gyrokinetic simulations of plasma turbulence in open-field-line geometries, using special versions of discontinuous-Galerkin (DG) algorithms to help with the computational challenges of the edge region. (Higher-order algorithms can also be helpful for exascale computing, because they reduce the ratio of communications to computations.)  We describe methods for handling positivity constraints, involving exponential reconstructions while preserving conservation properties of the underlying Hamiltonian system.  We have done simulations for an LAPD-type case and for a helical model of an SOL plasma with NSTX-type parameters.  Further details are in Shi, Hammett, Stoltzfus-Dueck, Hakim, J. Plasma Physics 83 (2017), 905830304, and E. L. Shi's 2017 Princeton thesis, https://arxiv.org/abs/1708.07283.