Quasilinear model for energetic particle diffusion in radial and velocity space

R. E. Waltz; E. M. Bass; G. M. Staebler

doi:10.1063/1.4802808

Quasilinear model for energetic particle diffusion in radial and velocity space

R. E. Waltz, E. M. Bass, G. M. Staebler

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13 Scopus citations

Abstract

A quasilinear model for passive energetic particle (EP) turbulent diffusion in radial and velocity space is fitted and tested against nonlinear gyrokinetic tokamak simulations with the GYRO code [J. Candy and R. E. Waltz, Phys. Rev. Lett. 91, 045001 (2003)]. Off diagonal elements of a symmetric positive definite 2 × 2 EP diffusion matrix account for fluxes up radial (energy) gradients driven by energy (radial) gradients of the EP velocity space distribution function. The quasilinear ratio kernel of the model is provided by a simple analytic formula for the EP radial and velocity space EP diffusivity relative to radial thermal ion energy diffusivity at each linear mode of the turbulence driven by the thermal plasma. The TGLF [G. M. Staebler, J. E. Kinsey, and R. E. Waltz, Phys. Plasmas 14, 0055909 (2007); ibid. 15, 0055908 (2008)] tokamak transport model provides the linear mode frequency and growth rates to the kernel as well as the nonlinear spectral weight for each mode.

Original language	English
Article number	042510
Journal	Physics of Plasmas
Volume	20
Issue number	4
DOIs	https://doi.org/10.1063/1.4802808
State	Published - Apr 2013
Externally published	Yes

Funding

This work was supported by the U.S. Department of Energy under GA-Grant Nos. DE-FG02-95ER54309 and SciDAC-GSEP Grant No. DE-FC02-08ER54977. The author wishes to thank Dr. David Pace for useful discussions initiating this work.

Funders	Funder number
U.S. Department of Energy	DE-FC02-08ER54977, DE-FG02-95ER54309

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Quasilinear model for energetic particle diffusion in radial and velocity space

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