Coupled simulations with SOLPS-ITER and B2.5-Eunomia for detachment experiments in Magnum-PSI

Abstract

Heat loads of 10MW m-2 are expected for steady state operation at ITER and up to 20MW m-2 in slow transient situations. Plasma linear devices like Magnum-PSI can recreate situations close as those expected to be achieved at ITER divertor, providing easier access for diagnostics than in a tokamak. Numerical models are still necessary to complement experiments and to extrapolate relevant information to fusion devices, as the relevant Atomic and Molecular (A\&M) processes. SOLPS-ITER (formerly known as B2.5-Eirene) is typically employed to solve the plasma and neutral distribution in a coupled way for tokamak devices. For Magnum-PSI, B2.5 has been coupled with a different neutral module, named Eunomia, developed mostly for linear devices. Nevertheless, there is an interest in using SOLPS-ITER for simulating Magnum-PSI, as it would ease the process of relating linear device results with tokamaks. A previous work found significant differences in the implementation of relevant plasma-neutral processes in Eirene and Eunomia. A wide range of plasma scenarios are compared between B2.5-Eunomia and SOLPS-ITER. Although both codes produce results close to experimental Thomson Scattering (TS) density and temperature near the target once the electric potential at the source is adjusted, these are achieved with completely different plasma and neutral distributions. Anomalous transport coefficients, which are other of the free-parameters in Magnum-PSI simulation, are set equal between the two codes. When studied in a wide range of neutral pressures, SOLPS-ITER shows a trend closer to experiments, as well as providing a converged solution at neutral pressures higher than $\unit[4]{Pa}$ for which B2.5-Eunomia was unable to provide a converged solution. Additional measurements of the neutral distribution in the target chamber as well as the electric potential at the source are required to determine which code is producing results closer to the experiment.

Deuterium retention in co-deposition with lithium in Magnum-PSI: experimental analysis and comparison with SOLPS-ITER

“…Once all of this is taken into account, the solid TZM case is produced as shown in figure 8. A good agreement between the simulation with SOLPS-ITER, which uses D as the main species, and the hydrogen calibration experimental shot is found, although electron density is slightly lower than in experiments, but still in an acceptable margin as in previous cases [40]. Additionally, this result is in good agreement with the experimental 200 • C solid TZM case, meaning that the use of a hydrogen shot in similar conditions to obtain upstream boundary conditions is a valid method if no source TS measurements…”

“…The target is assumed to have a 100% recycling of deuterium and lithium ions. During the solid target simulations, this assumption has been used in the past [39,40], while for the porous target it is assumed that the temperature is too high for the Li to retain D. The plasma flux reaching the edge of the beam is automatically recombined and acts as a source of neutral particles in Eirene, i.e. there are no ions outside the plasma beam.…”