Towards a unified linear kinetic transport model with the trace ion module for EIRENE

Abstract

Linear kinetic Monte Carlo particle transport models are frequently employed in fusion plasma simulations to quantify atomic and surface effects on the main plasma flow dynamics. Separate codes are used for transport of neutral particles (incl. radiation) and charged particles (trace impurity ions). Integration of both modules into main plasma fluid solvers provides then self-consistent solutions, in principle. The required interfaces are far from trivial, because rapid atomic processes in particular in the edge region of fusion plasmas require either smoothing and resampling, or frequent transfer of particles from one into the other Monte Carlo code. We propose a different scheme here, in which despite the inherently different mathematical form of kinetic equations for ions and neutrals (e.g. Fokker–Planck vs. Boltzmann collision integrals) both types of particle orbits can be integrated into one single code. We show that the approximations and shortcomings of this “single sourcing” concept (e.g., restriction to explicit ion drift orbit integration) can be fully tolerable in a wide range of typical fusion edge plasma conditions, and be overcompensated by the code-system simplicity, as well as by inherently ensured consistency in geometry (one single numerical grid only) and (the common) atomic and surface process modules.

A fluid-kinetic approach for 3D plasma edge transport in He plasma

“…Finally, the advancement of EMC3 to a multi-fluid code should be considered for the complete hybrid treatment of the He + ions. described and tested by Seebacher et al [32] in the frame of EIRENE. In [32, figure 3] a verification of the kinetic trace ion treatment is presented as a comparison of the Monte-Carlo results versus the relaxation time approximations.…”

“…Conventional Monte-Carlo schemes to simulate Fokker-Planck collision operators have been well established in plasma simulations for decades, see Boozer et al [25], Tani et al [26], Brizard [27], Fukano et al [28], Hirvijoki et al [29], Stangeby et al [30], Runov et al [31] and, within EIRENE, Seebacher et al [32]. They are all based on the equivalence between the Fokker-Planck equation and a corresponding stochastic differential equation, the trajectories of which have diffusive, advective and discontinuous (due to CX, wall interactions...) components in velocity space.…”

Simulation study of mixed-impurity seeding with extension of integrated divertor code SONIC

“…and the background ion heat flux parallel to the field line. The definitions of v j ˜ and q  are the same as [13]:…”

“…With the same objective, we have developed the integrated divertor plasma transport code SONIC [10,11]. One of the features of the SONIC code that is unique among the above codes is that it can compute the impurity transport processes kinetically by the Monte-Carlo (MC) particle code Impurity Monte Carlo (IMPMC), while most of the other codes, apart from calculations using the EIRENE ion module [12,13] or coupled calculation of SOLPS-IMPGYRO [14,15], treat impurity transport processes fluidly. Therefore, the SONIC code has the potential to provide more precise impurity transport/generation modelling such as ionization/ recombination of impurities, Coulomb collision processes, and plasma-wall interactions.…”