Simulations with the COREDIV code of DEMO discharges

Abstract

The reduction in divertor target power load due to radiation of sputtered and externally seeded impurities in tokamak fusion reactors is investigated. The approach is based on integrated numerical modelling of DEMO discharges using the COREDIV code, which self-consistently solves 1D radial transport equations of plasma and impurities in the core region and 2D multifluid transport in the SOL. Calculations are performed for inductive DEMO scenarios and for DEMO steady-state configurations with tungsten walls and Ar or Ne seeding. For all considered DEMO scenarios significant fusion power can be achieved. Increase in seeded impurity influx leads to the reduction in fusion power and Q-factor (defined as the ratio of fusion power to auxiliary heating power) due to plasma dilution. Total radiation appears to be almost independent of the puffing level and is dominated by core radiation (>90%). The radiation due to seeding impurity is small and the type of seeded impurity weakly affects the results. For pulsed DEMO concepts, the accessible seeding level is limited. There is no steady-state solution for stronger puffing. The solution terminates due to helium accumulation, and if confirmed by more detailed investigations, might strongly affect DEMO design.

Mitigation of the divertor heat load in DEMO reactor by impurity seeding

“…From one side, high radiation fraction (f rad > 80%) is mandatory and from the other side good confinement with the working point in H-mode is foreseen, which requires that the power to the SOL (power crossing the separatrix) is higher than the threshold power for L-H transition (P SOL > P LÀH ). From our earlier simulations [1], it comes out that the level of the power going to the SOL depends strongly on the tungsten radiation in the core, the latter being quite significant (about 50% of the core radiation). It is expected that by increasing the seeding level, the radiation in the SOL is increased, leading to the decrease of both the power to the plate and tungsten production.…”

“…In this paper, numerical simulation with the COREDIV code [1] of DEMO discharges with tungsten as the PFC material (divertor and wall) for H-mode scenarios are presented. Calculations are performed for the European inductive DEMO configuration [2] with Ne (Z = 10), Ar (Z = 18) and Ni (Z = 28) seeding.…”

Modeling of Tungsten Dust Transport in ITER with Multi‐Physics Code DUSTT/UEDGE

“…Second, for proper modeling of the behavior of high-z impurities in the tokamak plasma, self-consistent simulations of both core and boundary regions are necessary. Such modeling has been done, for example with COREDIV [10] under simplified plasma transport model assumptions, Recently, the development of sophisticated capabilities for whole device modeling has started [11]. However, it is important to note that impurity transport in the pedestal region, which is affected largely by transient events like ELMs and blobs, is poorly understood.…”

Limit on Reduction of the Power Load to Target Plates for DEMO Reactor

“…The code Corediv [3,4] solves self consistently the core and scrape off layer regions. The numerical analyses [2] show that there exists the limit on the concentration of impurities above which the solution with burning plasma does not exists. In order to seek better understanding of these phenomena several numerical tests are performed using Corediv code separately for core and SOL regions without coupling between two regions.…”

“…This coupling together with other nonlinear interactions leads to a complicated dependence of the solution on external control parameters. The several Demo design concepts [1] have been analyzed [2] using the code Corediv. The code Corediv [3,4] solves self consistently the core and scrape off layer regions.…”