Generalized curvature modified plasma dispersion functions and Dupree renormalization of toroidal ITG


Gultekin O., Gurcan O. D.

PLASMA PHYSICS AND CONTROLLED FUSION, cilt.62, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 62 Konu: 2
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1088/1361-6587/ab56a7
  • Dergi Adı: PLASMA PHYSICS AND CONTROLLED FUSION

Özet

A new generalization of curvature modified plasma dispersion functions is introduced in order to express Dupree renormalized dispersion relations used in quasi-linear theory. For instance the Dupree renormalized dispersion relation for gyrokinetic, toroidal ion temperature gradient driven (ITG) modes, where the Dupree's diffusion coefficient is assumed to be a low order polynomial of the velocity, can be written entirely using generalized curvature modified plasma dispersion functions: K-nm's. Using those, Dupree's formulation of renormalized quasi-linear theory is revisited for the toroidal ITG mode. The Dupree diffusion coefficient has been obtained as a function of velocity using an iteration scheme, first by assuming that the diffusion coefficient is constant at each v (i.e. applicable for slow dependence), and then substituting the resulting v dependence in the form of complex polynomial coefficients into the K-nm's for verification. The algorithm generally converges rapidly after only a few iterations. Since the quasi-linear calculation relies on an assumed form for the wave-number spectrum, especially around its peak, practical usefulness of the method is to be determined in actual applications. A parameter scan of eta(i) shows that the form of the diffusion coefficient is better represented by the polynomial form as eta(i) is increased.