205 / 2023-04-15 20:00:41

Derivation and numerical resolution of multi-component, multi-ion-temperature plasma flow models

multi-component; plasma flow; temperature disequilibrium; ICF

辐射和流体力学 > 高能量密度科学与温稠密物质-II

Motivated by the need for numerical simulation of the mixing phenomenon in ICF, the present research proposes a framework of hydrodynamic models for multi-component plasma in mechanical/thermal disequilibrium. In particular, recent experiments on Omega and NIF facilities (the MARBLE campaign) have demonstrated the significance of the ion temperature separation effect on the mixing topology and the thermonuclear reaction. As evaluated in previous results, the ion-temperature equilibrium assumption used in the classical plasma flow model may lead to a serious underestimation of the mixing length. To evaluate such temperature separation effect, the present paper proposes a series of models for describing multi-component multi-ion-temperature plasma flows. The interactions between multiple components are realized via component pressure/velocity/temperature relaxations. The relaxation processes in the proposed model properly consider the effect of the grain size in mixing. We have evaluated the relaxation time scales of different relaxation processes under the ICF condition. With these evaluations, we derive reduced models that keep the ion temperature disequilibrium and are computationally cheaper. The proposed model also takes the species interpenetration mixing into consideration through the component velocity disequilibrium. The model and the corresponding numerical methods are validated against several benchmark tests. Then we simulate a typical direct-drive implosion with the proposed approach in order to compare models with different ion temperature relaxation rates. The simulation results provide important references for evaluating the validity of closure assumptions in ICF plasma flows.