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Author: Jungpyo Lee
Requested Type: Poster
Submitted: 2017-03-16 14:38:22

Co-authors: Yu. V. Petrov, David Smithe, John Wright, R. W. Harvey, Lee Berry, and Paul Bonoli

Contact Info:
MIT
77 Massachusetts Avenue
Cambridge,   02139
USA

Abstract Text:
We present an analytical form of the quasilinear diffusion coefficients for a toroidal geometry that are modified from the Kennel-Engelmann (K-E) diffusion coefficients [1]. When K-E coefficients are based on the homogenous plasma and background magnetic fields along the particle trajectory, this simplification can fail to insure positive-definiteness of the bounce average of the coefficients in toroidal geometry. Our form guarantees the positive definiteness and includes the toroidal effects more accurately. When the correlation length of plasma-wave interactions is comparable to the length of the magnetic field variation, the variation needs to be considered in the trajectory integral instead of a Dirac-delta function in K-E coefficients. For ICRF waves in a toroidal geometry, the parabolic variation of the magnetic fields in the trajectory integral around the outer-midplane or the inner-midplane is evaluated by Airy functions. They allow the coefficients to include both resonant and non-resonant contributions and capture the correlation between the consecutive resonances. These new characteristics of our form are verified by a particle code, DC [2], which measures the test particle diffusion due to the Lorentz force of the RF fields. Some distinctive features compared to the K-E coefficients are found around the flux surface that is tangential to the ion cyclotron layer.

[1] C. F. Kennel and F. Engelmann, Phys. Fluids 9, 2377 (1966)
[2] R. W. Harvey, Yu. V. Petrov, E. Jaeger, and RF SciDAC Group, in 19th Topical Conference on Radio 
Frequency Power in Plasmas (2011) 1406, 369 



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