Padé approximation of the adiabatic electron contribution to the gyrokinetic quasi-neutrality equation in the ORB5 code

Joint Varenna-Lausanne International Workshop on the Theory of Fusion Plasmas 2016

Lanti, E.^1 ; Dominski, J.^1 ; Brunner, S.^1 ; McMillan, B.F.^2 ; Villard, L.^1

Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), Lausanne

CH-1015, Switzerland^1

Centre for Fusion, Space and Astrophysics, Department of Physics, Warwick University, Coventry, United Kingdom^2

关键词: Gyrokinetic codes;    Kinetic electrons;    Linear dispersion relations;    Linear growth rate;    Neutrality equations;    Pade approximation;    Polarization response;    Quasineutrality;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/775/1/012006/pdf
DOI  :  10.1088/1742-6596/775/1/012006

来源: IOP

【 摘 要 】

This work aims at completing the implementation of a solver for the quasineutrality equation using a Padé approximation in the global gyrokinetic code ORB5. Initially [Dominski, Ph.D. thesis, 2016], the Pade approximation was only implemented for the kinetic electron model. To enable runs with adiabatic or hybrid electron models while using a Pade approximation to the polarization response, the adiabatic response term of the quasi-neutrality equation must be consistently modified. It is shown that the Pade solver is in good agreement with the arbitrary wavelength solver of ORB5 [Dominski, Ph.D. thesis, 2016]. To perform this verification, the linear dispersion relation of an ITG-TEM transition is computed for both solvers and the linear growth rates and frequencies are compared.