Description
Taming excessive heat- and particle fluxes arriving to the first wall is one of the most pressing issues on the way to a fusion reactor in magnetically confined devices. The problem itself is two-fold, both steady state fluxes in divertor configurations and transient loads due to turbulence/MHD transients have to be mitigated in order to ensure safe operation. A regime in tokamaks, that has shown to achieve both is the X-Point Radiator (XPR). This regime features a highly radiative, dense and cold region just inside the confined region and has promising control capabilities. In H-mode, Type-I ELMs are suppressed when the XPR reaches a threshold height. This regime has been extensively studied both experimentally and in modeling. But so far, no modeling was capable to self-consistently simulate both the SOL processes leading to the XPR and the MHD edge instabilities, at the same time.
In this contribution, we present the recent progress of modeling an established XPR and its interplay with edge MHD instabilities. The extended visco-resistive MHD code JOREK is used with its full-f particle-in-cell kinetic extension for neutrals and impurities. The extension allows for self-consistent modeling of the XPR regime, utilizing the existing capability of JOREK to simulate the plasma from the core to the first wall. Simulations, in the absence of instabilities are validated on experiments on the ASDEX Upgrade tokamak, and XPRs achieved with different impurity species are compared. The extended linear stability of the pedestal is scanned at different XPR heights, and the nonlinear dynamics are analyzed, including the loss of the XPR due to ELMs. The aim of this work is to further understand the ELM suppression phenomena observed in present day tokamaks, and later investigate its possibility in ITER.