Speaker
Description
The next generation of fusion reactors will face unprecedented conditions in terms of power exhaust from the burning plasma. Quantifying heat loads due to impurity radiation following line and bremsstrahlung emission, as well as recombination, is essential for the thermo-mechanical design of plasma-facing components. This work describes the development of an integrated framework for the assessment of radiative power deposition on reactor first wall, combining core, scrape-off layer (SOL) plasma, and neutral modeling with 3D radiation transport.
Within this framework, an interface was developed capable of loading radiation source data provided by ASTRA/STRAHL or SOLPS-ITER, which are then processed with the Monte Carlo radiation transport code Raysect-CHERAB. As a first example, we discuss here a set of steady-state plasma scenarios, where Xenon has been included as core radiator, while Argon accounts for the SOL contribution. Also, He is present in the plasma composition, which refers to a reactor producing about 2 GW fusion power. The edge volumetric energy source has been evaluated with the SOLPS-ITER code wide-grid version, which allows extending the plasma computation up to the chamber wall. When running coupled with the EIRENE code for neutral gas transport, the neutral load due to high-energy charge-exchange atoms can also be included on the top of radiative calculations. This allows a quite comprehensive assessment of thermal and erosion wall exposure, which might be critical for reactor design. Sources are produced by plasma codes in the form of 2D poloidal maps and then mapped to the full toroidal domain assuming plasma axisymmetry before feeding them as input to Raysect-CHERAB.
As a preliminary assessment we consider the EU-DEMO reactor for a low-aspect ratio configuration (DEMO-LAR) to test our workflow performance. Preliminary calculations suggest a power load onto the wall within the range of $0.08-0.2\,\mathrm{MW\,m^{-2}}$, with peak values localized on the outboard segment of the first wall. Due to the high recycling and detached conditions required for divertor protection, strong localized sources in proximity of target surfaces can lead to peak heat load of $2.30\,\mathrm{MW\,m^{-2}}$ near strike points.
The workflow proposed here aims primarily at the evaluation of radiative loading conditions to directly support the thermo-mechanical design and assessment of the EU-DEMO-LAR first wall. It is sufficiently flexible to allow, in perspective, extensions to other reactor-relevant applications such as the development of spectroscopic synthetic diagnostics.