SolEdge2D-Eirene simulations of Pilot-PSI plasmas

The exhaust of power is a crucial issue for ITER and next step fusion devices [1]. Predictions for divertor operation are heavily dependent on edge plasma simulations typically utilizing a fluid plasma code in combination with a Monte Carlo code for neutral species. Therefore it is important to validate the codes using well-diagnosed experimental setups. The Pilot-PSI device offers a high density (n_e ~ 10¹⁹ – 10²¹ m^-3), low temperature (T_e < 5.0 eV) plasma comparable to that expected in the ITER divertor region. In this work, hydrogen plasma discharges in Pilot-PSI have been modelled using the Soledge2D fluid plasma code [2] coupled to the Eirene neutral Monte Carlo code. In the model, the plasma is generated using external volumetric sources of plasma density and power in the region of the cascaded arc plasma source and a constant H₂ gas inflow rate. The external power source is found to be the main control parameter of the simulations and is set in order to match experimental n_e, T_e profiles from Thomson scattering (TS) 4 cm downstream of the cascaded arc nozzle. The total injected power is typically 2 – 3 kW. The simulation results are compared to TS measurements 56 cm downstream from the source nozzle (2 cm in front of the Pilot-PSI target) and a Langmuir probe embedded in the target.