Non-Maxwellian background effects in gyrokinetic simulations with GENE

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

Di Siena, A.^1 ; Görier, T.^1 ; Doerk, H.^1 ; Citrin, J.^2,3 ; Johnson, T.^4 ; Schneider, M.^3 ; Poli, E.^1

Max Planck Institute for Plasma Physics, Boltzmannstr.2, Garching

85748, Germany^1

FOM Institute DIFFER, PO Box 6336, Eindhoven

5600 HH, Netherlands^2

CEA, IRFM, Saint Paul Lez Durance

F-13108, France^3

VR Association, EES, KTH, Stockholm, Sweden^4

关键词: Background effects;    Carbon impurities;    Distributed particles;    Gyrokinetic codes;    Gyrokinetic simulations;    Linear growth rate;    Microinstabilities;    Non-Maxwellian distribution;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/775/1/012003/pdf
DOI  :  10.1088/1742-6596/775/1/012003

来源: IOP

【 摘 要 】

The interaction between fast particles and core turbulence has been established as a central issue for a tokamak reactor. Recent results predict significant enhancement of electromagnetic stabilisation of ITG turbulence in the presence of fast ions. However, most of these simulations were performed with the assumption of equivalent Maxwellian distributed particles, whereas to rigorously model fast ions, a non-Maxwellian background distribution function is needed. To this aim, the underlying equations in the gyrokinetic code GENE have been re-derived and implemented for a completely general background distribution function. After verification studies, a previous investigation on a particular JET plasma has been revised with linear simulations. The plasma is composed by Deuterium, electron, Carbon impurities, NBI fast Deuterium and ICRH3He. Fast particle distributions have been modelled with a number of different analytic choices in order to study the impact of non-Maxwellian distributions on the plasma turbulence: slowing down and anisotropic Maxwellian. Linear growth rates are studied as a function of the wave number and compared with those obtained using an equivalent Maxwellian. Generally, the choice of the3He distribution seems to have a stronger impact on the microinstabilities than that of the fast Deuterium.