Global SOLPS-ITER and ERO2.0 coupling in a linear device for the study of plasma-wall interaction in helium plasma

Plasma–wall interaction (PWI) is a great challenge in the development of a nuclear fusion power plant. To investigate phenomena like erosion of plasma-facing components, impurity transport and redeposition, one needs reliable numerical tools for the description of both the plasma and the material evolution. The development of such tools is essential to guide the design and interpretation of experiments in present and future fusion devices. This contribution presents the first global simulation of PWI processes in a linear plasma device mimicking the boundary plasma conditions in toroidal ones, including both the description of plasma and impurity transport and of plasma-facing material evolution. This integrated description is obtained by coupling two of the state-of-the-art numerical codes employed to model the plasma boundary and the PWI, namely SOLPS-ITER and ERO2.0. Investigation of helium plasma is also of primary importance due to the role helium will have during ITER pre-fusion power operation, when it is planned to be used as one of the main plasma species, as well as fusion ash in full power operation. The plasma background is simulated by SOLPS-ITER and the set of atomic reactions for helium plasmas is updated, including charge-exchange and radiative heat losses. ERO2.0 is used to assess the surface erosion in the GyM vessel, using different wall materials (e.g. carbon, iron or tungsten) and applying different biasing voltage. Eroded particles are followed within the plasma to assess their redeposition location. The ionization probability of the different materials in the GyM plasma is inferred through the energy distribution of impacting particles and its effects on migration are investigated

Validation of the plasma-wall interaction simulation code ERO2.0 by the analysis of tungsten migration in the open divertor region in the Large Helical Device

Tungsten migration in the open divertor region in the Large Helical Device is analyzed for validating the three-dimensional plasma-wall interaction simulation code ERO2.0. The ERO2.0 simulation reproduced the measurement of localized tungsten migration from a tungsten-coated divertor plate installed in the inboard side of the torus. The simulation also explained the measurement of the high tungsten areal density in the private side on a carbon divertor plate, next to the tungsten-coated divertor plate, by the tungsten prompt redeposition in plasma discharges for a low magnetic field strength in a counterclockwise toroidal direction. However, the simulation disagreed with the measurement of low tungsten areal density on the plasma-wetted areas on the carbon divertor plates, which indicated that the actual erosion rate of the redeposited tungsten should be much higher than that used in the ERO2.0 code

Data on erosion and hydrogen fuel retention in Beryllium plasma-facing materials

ITER will use beryllium as a plasma-facing material in the main chamber, covering a total surface area of about 620 m(2). Given the importance of beryllium erosion and co-deposition for tritium retention in ITER, significant efforts have been made to understand the behaviour of beryllium under fusion-relevant conditions with high particle and heat loads. This paper provides a comprehensive report on the state of knowledge of beryllium behaviour under fusion-relevant conditions: the erosion mechanisms and their consequences, beryllium migration in JET, fuel retention and dust generation. The paper reviews basic laboratory studies, advanced computer simulations and experience from laboratory plasma experiments in linear simulators of plasma-wall interactions and in controlled fusion devices using beryllium plasma-facing components. A critical assessment of analytical methods and simulation codes used in beryllium studies is given. The overall objective is to review the existing set of data with a broad literature survey and to identify gaps and research needs to broaden the database for ITER.Peer reviewe

EUROfusion Integrated Modelling (EU-IM) capabilities and selected physics applications

International audienceRecent developments and achievements of the EUROfusion Code Development for Integrated Modelling project (WPCD), which aim is to provide a validated integrated modelling suite for the simulation and prediction of complete plasma discharges in any tokamak, are presented. WPCD develops generic complex integrated simulations, workflows, for physics applications, using the standardized European Integrated Modelling (EU-IM) framework. Selected physics applications of EU-IM workflows are illustrated in this paper

3D simulation of impurity transport in a fusion edge plasma using a massively parallel Monte-Carlo code

Thermonuclear fusion of deuterium (D) and tritium (T) has the potential to be an efficient, sustainable and safe source of energy. The international tokamak fusion experiment ITER (Latin: "the way"), which is scheduled to start operation in 2027, is a key project for the realization of this technology. Reliable predictions on the plasma-wall interaction (PWI) are critical to the success of ITER and further upcoming fusion reactors, since these will significantly impact their efficiency and lifespan. An important PWI process is the erosion of the reactor wall. It determines the lifetime of wall components and is also a source of impurities in the plasma, namely beryllium (Be) and tungsten (W) in the case of the metallic ITER first wall. Codeposition and retention of radioactive T with eroded Be is a significant issue for ITER, since its T wall inventory has an administrative limit of 700 g for safety and fuel cycle reasons. The penetration of impurities (in particular of W, which can reach a high degree of ionization) into the plasma core leads to its cooling due to radiative energy losses, which has a deteriorating impact on confinement and stability. The three-dimensional Monte Carlo (MC) code ERO is an established tool for the investigation and prediction of PWI and plasma impurity transport in fusion experiments. However, due to technical aspects, such as most importantly the limited code performance, ERO was used so far for examining small simulation volumes (under $\sim$ 1m$^{3}$), which is a small fraction of the ITER plasma volume($\sim$ 800m$^{3}$). Thus, addressing the interdependent problem of impurity transport and PWI in the tokamak has demanded additional assumptions (for example, on the impurity content in the plasma). Moreover, the possibilities of code validation based on measurements in fusion experiments were limited, since only local diagnostics could be used. In the framework of this thesis, the ERO code has been redeveloped from scratch to remove these restrictions. The new code ERO2.0 implements algorithms that allow to study large and complexly shaped wall components in a simulation volume of the ITER plasma vessel size. The resulting increased complexity of the simulation requires to enhance the code performance by orders of magnitude. [...

3D-simulation of impurity transport in a fusion edge plasma by means of a massively parallelized Monte-Carlo code

Die Erosion von Wandkomponenten und die Tritiumrückhaltung begrenzen die Verfügbarkeit und Lebensdauer von ITER und zukünftiger Fusionsreaktoren. Für die Interpretation und Vorhersage der zugrundeliegenden physikalischen Prozesse wurde der Simulationscode ERO2.0 entwickelt. Dieser ermöglicht die 3D-Simulation der Plasma-Wand-Wechselwirkung und des globalen Verunreinigungstransportes im gesamten Randschichtplasmabereich einer Fusionsanlage. Die erforderliche Rechenleistung wird durch effiziente massive Parallelisierung des Codes gewährleistet. In einem ersten Anwendungsfall wurde die Erosion von Beryllium-Wandkomponenten in der Hauptkammer des JET-Tokamaks simuliert. Durch das Verfolgen der vollständigen Trajektorien der erodierten Teilchen konnte der Einfluss der Be-Selbstzerstäubung erstmalig selbstkonsistent beschrieben werden. Die Ergebnisse der Modellierung wurden erfolgreich mit experimentellen Spektroskopiedaten verifiziert.Erosion of wall components and tritium retention limit lifetime and availability of ITER and future fusion reactors. The simulation code ERO2.0 was developed for the interpretation and prediction of the involved physical processes. The code enables a 3D simulation of plasma-wall interaction processes and the global impurity transport in the entire edge plasma region of a fusion device. The required computing power is realized by efficient massive parallelization of the code. In a first application, the erosion of beryllium wall components in the main chamber of the JET tokamak was simulated. For the first time the influence of Be self-sputtering was self-consistently described by tracking the full trajectories of eroded particles. The modelling results were successfully verified by comparison with experimental spectroscopy data

Implementation and validation of guiding centre approximation into ERO2 .0

The Monte-Carlo code ERO2.0 uses full orbit resolution to follow impurity particles throughout the plasma volume to determine the local erosion and deposition fluxes on the plasma-facing components of fusion devices in magnetic confinement fusion. To have direct comparisons to other transport codes (e.g., ASCOT and DIVIMP) and to accelerate the code, guiding centre approximation (GCA) was implemented into ERO2.0. In addition, a hybrid simulation mode for ERO2.0 was developed, in which the advantages of both full orbit resolution and guiding centre approximation are used. In typical scenarios in this simulation mode, full orbit resolution is applied exclusively near the wall region, while GCA is used everywhere else along a particle's trajectory. Special emphasis was put on the validation of the implementation by an inner-code benchmarking to pure full orbit simulations. Analysed scenarios included test plasmas with simplified geometry and a realistic test case corresponding to a deuterium limiter plasma used in JET pulse #80319. The results of simulations performed in the hybrid simulation mode are in very good agreement to corresponding pure full orbit simulations, while a significant code speed-up was achieved

Multiphysics Modeling of Impurity Transport for FNSF Startup Scenario with ERO2.0

This study focuses on performing a multiphysics study using the ERO2.0 and UEDGE codes for two standard double null configurations for the Fusion Nuclear Science Facility: (a) 100% recycling and (b) 99% recycling. Results show that the main contributor to tungsten erosion along the divertor plates is impurities from the midplane waveguides. In addition, the standard high-recycling case (100% recycling) shows a significantly higher buildup of impurities along the divertor tiles during the startup phase, which can lead to a higher increase of energy loss in the plasma during steady-state operation. Last, for high recycling, anomalous diffusion can dominate over parallel field diffusion. The work performed in this study can be iteratively applied to a full operation scenario with additional physics such as those from neutrals, wall shaping, and additional external fields

Nitrogen molecular break-up and transport simulations in the JET divertor

| openaire: EC/H2020/633053/EU//EUROfusionThe density of N+ ions is predicted to decrease by 25 % and the density of N2+ ions to increase by 50 % if nitrogen is assumed to recycle from the divertor walls as molecules in partially detached JET L-mode plasma simulations performed with the 3D Monte Carlo trace impurity code ERO2.0 [1]. These findings are attributed to the kinetic energy gained by the molecular dissociation fragments in the Franck-Condon process and the resulting increase in plasma penetration of the atoms.Non peer reviewe