Speaker
Amil Sharma
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1105.pdf
Strong-flow gyrokinetic simulations with a unified treatment of all length
scales
A.Y. Sharma1 , B.F. McMillan1 , J. Dominski2
1 University of Warwick, Coventry, UK
2 Princeton Plasma Physics Laboratory, Princeton, US
Tokamak turbulence exhibits interaction on all length scales, but standard gyrokinetic treat-
ments consider global scale flows and gyroscale flows separately, and assume a separation be-
tween these length scales. However, the use of a small-vorticity ordering [1, 2] allows for the
presence of large, time-varying flows on large length scales, whilst providing a unified treatment
including shorter length scales near and below the gyroradius. We present a numerical scheme
for the solution of gyrokinetic equations using such an ordering.
For simplicity, we use two-dimensional electrostatic potential perturbations in slab and cylin-
drical magnetic geometries. In an analogous way to that of the vk -formulation of gyrokinetics,
the partial time derivative of the E × B flow is present in our Euler-Lagrange and Poisson equa-
tions. These terms must be kept to ensure energetic consistency [3]. However, these terms are
small compared to all other terms, allowing for the use of an iterative numerical scheme.
Our numerical implementation uses the δ f particle-in-cell method [4], and employs an arbitrary-
wavelength Poisson solver [5]. We have performed code verification using basic slab instabili-
ties. We present comparative weak- and strong-flow simulation results for centrifugal and drift
instabilities. We simultaneously simulate supersonic fluctuating flows at large length scales and
the cascade of shorter wavelength flows down to the gyroradius.
References
[1] A.M. Dimits, Physics of Plasmas 17, 055901 (2010)
[2] B.F. McMillan and A.Y. Sharma, Physics of Plasmas 23, 092504 (2016)
[3] B. Scott and J. Smirnov, Physics of Plasma 17, 112302 (2010)
[4] S. Jolliet, A. Bottino, P. Angelino, R. Hatzky, T.-M. Tran, B.F. McMillan, O. Sauter, K. Appert, Y. Idomura,
L. Villard, Computer Physics Communications 177, 409 (2007)
[5] J. Dominski, B.F. McMillan, S. Brunner, G. Merlo, T.-M. Tran and L. Villard, Physics of Plasmas 24, 022308
(2017)
