SOLPS-ITER modeling of beryllium trace impurity in ITER

Beryllium transport modeling was carried out in the trace impurity regime by SOLPS-ITER code for tokamak ITER. It is valuable for developing of diagnostics protection from beryllium deposition. TRIM reflection model and Bogdanskii formula sputtering model were applied. The idea is to show possibility of using this code for beryllium transport. This code has key advantage comparing to other codes, which study beryllium transport, because in it the main plasma and impurities are described self-consistently. Therefore, if beryllium affect the background plasma, only this code can take this effect into account. Test calculations were performed with suppressed sputtering yield by 10 times, to reach trace impurity regime. Main features of behavior of beryllium in the tokamak were studied, however under restriction of static wall conditions. Sources, sinks, fluxes and density distribution were determined. In this test calculation plasma state kept unchanged as expected. Distribution of impinging and absorbed fluxes on the outer divertor plate were established in the position of divertor diagnostics. Main ways for the further improvement are suggested.

Set of wires to simulate tokamaks with poloidal divertor

Simple wire models have been proposed to simulate magnetic configurations in tokamaks. Here we consider electric currents in five parallel infinite wires to obtain double-null magnetic surfaces with specific choices of magnetic axis positions, triangularity, and elongation. As an example, we choose the position and the electric current of each wire to obtain magnetic surfaces similar to those expected in the tokamak international thermonuclear experimental reactor. Moreover, we also integrate the perturbed field line differential equation to simulate chaotic layers near the hyperbolic points and deposition patterns at the divertor plate observed in tokamaks. To simulate that, we add to the model a perturbing error field, due to asymmetries in the tokamak coils, and introduce a random collisional term to the field line mapping to reproduce escape pattern alterations due to particle collisions.