A first-principles self-consistent model of plasma turbulence and kinetic neutral dynamics in the tokamak scrape-off layer

Abstract

A first-principles self-consistent model that couples plasma and neutral physics suitable for the simulation of turbulent plasma behavior in the tokamak SOL is presented. While the plasma is modeled by the drift-reduced two fluid Braginskii equations, a kinetic model for the neutrals is developed, valid in short and in long mean free path scenarios. The model includes ionization, charge-exchange, recombination, and elastic collisional processes. The solution of the neutral kinetic equation is implemented within the GBS plasma turbulence code (Ricci et al 2012 Plasma Phys. Control. Fusion 54 124047) and it is performed by using the method of characteristics. The details of the numerical implementation are discussed. Finally, we show initial results of the first self-consistent simulations of plasma turbulence and neutral dynamics.

Plasma particle sources due to interactions with neutrals in a turbulent scrape-off layer of a toroidally confined plasma

“…which have approximately the same relative value as prescribed by (9). Note that the neutral terms have been normalized with parameters that relate to the plasma parameters and not to those of the neutrals.…”

“…Both kinetic neutral models such as [9][10][11][12] , and fluid models [13][14][15][16] have previously been applied to study SOL and edge plasmas in the presence of neutrals. In this paper we derive a 2 neutral fluid model for the purpose of studying the effects of neutrals on the intermittent plasma fields.…”

Recent EUROfusion Achievements in Support of Computationally Demanding Multiscale Fusion Physics Simulations and Integrated Modeling

“…One important application for the improved GBS is the investigation of SOL turbulence self-consistently with the neutral dynamics implemented recently in this code. 22 Presently, the BIT2 code simulates multiple plasma species and neutrals in the 2D space using ad-hoc anomalous cross-field diffusion coefficients. Although it is capable to simulate electrostatic turbulence selfconsistently with plasma profiles, these simulations would be extremely time consuming taking into account the typically small simulation time step (≈10 -12 s) needed to resolve the Debye shielding and Larmor rotation, while the characteristic SOL turbulence time is much larger (10 -4 to 10 -5 s) and its accounting requires long simulations.…”

A comparison between a refined two-point model for the limited tokamak SOL and self-consistent plasma turbulence simulations

“…[18,19].) The electron temperature drop from the upstream to the target location predicted by this model, which is implemented in the GBS code [4,5], is then compared with the simple two-point model.…”