Validation of edge turbulence codes against the TCV-X21 diverted L-mode reference case

Abstract

Self-consistent full-size turbulent-transport simulations of the divertor and SOL of existing tokamaks have recently become feasible. This enables the direct comparison of turbulence simulations against experimental measurements. In this work, we perform a series of diverted Ohmic L-mode discharges on the TCV tokamak, building a first-of-a-kind dataset for the validation of edge turbulence models. This dataset, referred to as TCV-X21, contains measurements from 5 diagnostic systems -- giving a total of 45 1- and 2-D comparison observables in two toroidal magnetic field directions. The dataset is used to validate three flux-driven 3D fluid-turbulence models: GBS, GRILLIX and TOKAM3X. With each model, we perform simulations of the TCV-X21 scenario, tuning the particle and power source rates to achieve a reasonable match of the upstream separatrix value of density and electron temperature. We find that the simulations match the experimental profiles for most observables at the OMP -- both in terms of profile shape and absolute magnitude -- while a poorer agreement is found towards the divertor targets. The match between simulation and experiment is seen to be sensitive to the value of the resistivity, the heat conductivities, the power injection rate and the choice of sheath boundary conditions. Additionally, despite targeting a sheath-limited regime, the discrepancy between simulations and experiment also suggests that the neutral dynamics should be included. The results of this validation show that turbulence models are able to perform simulations of existing devices and achieve reasonable agreement with experimental measurements. Where disagreement is found, the validation helps to identify how the models can be improved. By publicly releasing the experimental dataset, this work should help to guide and accelerate the development of predictive turbulence simulations of the edge and SOL.

References in corpus (6)

• Array Programming with NumPy
• Validation in Fusion Research: Towards Guidelines and Best Practices
• Global turbulence simulations of the tokamak edge region with GRILLIX
• The GBS code for the self-consistent simulation of plasma turbulence and kinetic neutral dynamics in the tokamak boundary
• Application of Gaussian process regression to plasma turbulent transport model validation via integrated modelling
• On Ohm's law in reduced plasma fluid models

Cited by in corpus (14)

• The GBS code for the self-consistent simulation of plasma turbulence and kinetic neutral dynamics in the tokamak boundary
• X-point and divertor filament dynamics from Gas Puff Imaging on TCV
• Tokamak edge-SOL turbulence in H-mode conditions simulated with a global, electromagnetic, transcollisional drift-fluid model
• New insights on divertor parallel flows, ExB drifts, and fluctuations from in situ, two-dimensional probe measurement in the Tokamak à Configuration Variable
• Full-F Turbulent Simulation in a Linear Device using a Gyro-Moment Approach
• Validation of GBS plasma turbulence simulation of the TJ-K stellarator
• On the Turbulent Behavior of a Magnetically Confined Plasma Near the X-Point
• Validation of SOLPS-ITER Simulations against the TCV-X21 Reference Case
• On the 3D turbulence regime in a Tokamak plasma edge
• On the Effects of Tokamak Plasma Edge Symmetries on Turbulence Relaxation
• Three-dimensional boundary turbulence simulations of a RFX-mod plasma in the presence of voltage biasing
• Turbulent transport regimes in the presence of an X-point magnetic configuration
• Multi-Machine Scaling Laws for Fuel and Impurity Puffing Rates Sufficient for Detachment Access: a Systematic Review of Magnetic Confinement Fusion Devices
• Conservative formulation of the drift-reduced fluid plasma model