A global quasilinear critical gradient model for Alfven eigenmode transport of energetic particles¹

-R.E. WALTZ and E.M. BASS, General Atomics.  The local critical gradient model (CGM) for the transport of energetic particles (EP) by Alfven eigenmodes (AEs) has been verified by local nonlinear GYRO gyrokinetic simulations[1], validated by DIII-D experiments[2], and used to predict ITER EP confinement loss[3]. A new global quasilinear critical gradient model (GQLCGM) is presented. Global linear GYRO simulations of a DIII-D discharge are advanced in time with the GYRO quasilinear EP transport fluxes fed to an ALPHA-like EP density transport code[3]. The relaxing driving EP density gradient profile is fed-back to GYRO until the most unstable global AE mode reaches a marginal state. A global critical gradient and EP transport profiles with significant large EP orbit effects is obtained and compared to the local CGM.  

[1] E. M. Bass and R. E. Waltz, Phys. Plasmas 17, 112319 (2010)

[2] R.E. Waltz, E.M. Bass, W.W. Heidbrink, and M.A. VanZeeland, Nucl. Fusion 55 123012 (2015)

[3] R. E. Waltz and E. M. Bass, Nucl. Fusion 54, 104006 (2014)

¹ Work supported by U.S. Department of Energy under Grants DE-FG02-95ER54309 (theory), DE-SC0018108 (SciDAC-ISEP project), and DE-FC02-04ER54698 (DIII-D).