Introducing FACETS, the Framework Application for Core-Edge Transport Simulations

Abstract

The FACETS (Framework Application for Core-Edge Transport Simulations) project began in January 2007 with the goal of providing core to wall transport modeling of a tokamak fusion reactor. This involves coupling previously separate computations for the core, edge, and wall regions. Such a coupling is primarily through connection regions of lower dimensionality. The project has started developing a component-based coupling framework to bring together models for each of these regions. In the first year, the core model will be a 1 ½ dimensional model (1D transport across flux surfaces coupled to a 2D equilibrium) with fixed equilibrium. The initial edge model will be the fluid model, UEDGE, but inclusion of kinetic models is planned for the out years. The project also has an embedded Scientific Application Partnership that is examining embedding a full-scale turbulence model for obtaining the crosssurface fluxes into a core transport code.

Dynamic Models for Plasma‐Wall Interactions

“…, where index k runs over the incident species, σ kl ij is the cross-section of the l process, σ is the characteristic function of projectile energy E k with threshold w kl ij , and Φ k (x) is the profile of incident flux versus depth x. WallPSI was designed to be a component in a self-consistent core-edge-wall modeling suite for tokamaks, e.g., in the FACETS project [10]. FACETS is aimed at integrated simulations for next-step fusion devices by combining multiple existing physics components (Gyrokinetic, magnetohyrdrodynamic, neutral-beam injection, radio-frequency, and transport codes) using massively parallel computing resources available at supercomputing leadership class facilities.…”

“…FACETS also provides the interface and network tools for implicit coupling of the WallPSI and UEDGE codes through data exchange of particle and energy fluxes. Self-consistent 2-D wall-edge plasma modeling is in progress [10]. Supersaturated layer formation.…”

“…We used an explicit time scheme for WallPSI and EDGE1D coupling, in which we sequentially advanced the codes on the same time step δ t and updated the step-averaged particle and energy influxes at each code iteration. Although δ t can vary during coupled iterations based on power and particle balances, the typical δ t was very small, around 10 −10 s, under high recycling SOL conditions and simulations were very time consuming (note that more efficient, implicit coupling scheme recently has been employed in FACETS [10]).…”

“…To address all these issues, sophisticated integrated multi-physics modeling capabilities are needed. Super-projects like the Fusion Simulation Program (FSP) [7,10] have been initiated to confidently predict magnetic fusion device behavior and nonlinearly-coupled phenomena in the core plasma, edge plasma, and material wall regions.…”

“…The most advanced MT code is TMAP7 [12], which is widely used in Thermal Desorption Spectroscopy (TDS) data analysis and in safety analysis for fusion devices. MT codes were also developed aiming at self-consistent modeling of coupled plasma and wall dynamics, e.g., WallPSI [10,24]. The physics of incident particle backscattering, implantation, sputtering, material damage, profiles of recoil atoms, etc are extensively studied with Particle Monte Carlo codes based on a binary-collision test-particle approximation [13,14].…”