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Author: Eric D. Held
Requested Type: Poster
Submitted: 2016-02-15 08:33:56

Co-authors: S.E. Kruger, J.R. King and T.G. Jenkins

Contact Info:
Utah State University
4415 Old Main Hill
Logan, UT   84322-4

Abstract Text:
The interaction of energetic particles with macroscopic fluid modes in magnetized fusion plasmas affects both stability and transport. In order to better understand these interactions, a continuum solution to the drift kinetic equation (DKE) for energetic particles has been implemented in the NIMROD code
and used in different applications. Two advantages of the continuum hot particle implementation are (1) that the solution to the DKE is fully implicit in time and (2) that a finite-element approach in pitch-angle effectively resolves trapped/passing physics in velocity space. In one application, NIMROD's continuum energetic particle and two-fluid models are used to verify
RSAE/TAE physics with the TAEFL, GYRO and GTC codes. Agreement on the evolving real frequency as the minimum in the q-profile increases is shown between the four codes and DIII-D shot #142111. In another application, efforts to model giant sawtooth cycles in DIII-D shot #96043 are summarized. Here an energetic
ion population induced by RF heating modifies the sawtooth stability. Linear calculations quantifying the effect of slowing-down, RF-tail and thermal ions on linear growth rates are shown to be consistent with the onset of the giant sawtooth crash in the experimental discharge.