The development of plasma facing materials (PFMs) able to withstand the harsh conditions (large thermal loads and radiation-induced damage) in reactors is one of the key parameters for nuclear fusion to upscale to commercial power plants both, in inertial confinement fusion (ICF) and in the magnetic confinement fusion (MCF) approaches.
The radiation environment that PFMs will face in nuclear...
In a fusion reactor, tungsten will be exposed to high heat flux, neutrons, helium ash, and tritium-containing fuel plasma. Neutron irradiation generates defects in tungsten, and the migration of these defects under irradiation leads to their clustering and annihilation. These irradiation-induced defects serve as strong trapping sites for hydrogen isotopes. Therefore, predicting the...
The general problem of first principles force fields is to create surrogate models for quantum mechanics that yield the energy of a configuration of atoms in 3D space, as we would find them in reality for materials or molecules. Over the last decade significant advances were made in the attainable accuracy, and today we can model materials and molecules with a per-atom energy accuracy of up to...
In nuclear fusion environments, structural materials must withstand severe thermal loads and high-energy particle bombardment. Accurately simulating these conditions requires large-scale atomistic models capable of capturing complex grain and interface arrangements. PolyPal provides a big solution by generating massive polycrystalline specimensโscaling to tens of billions of atomsโin only a...
Excess lattice point defects can drive phase transformations, alter phase selection, or even lead to the formation of new phases. The removal of these defects serves both as a mechanism for accommodating precipitate eigenstrain and as a driving force for semi-coherent precipitation [1].
We present a thermodynamic framework for point-defect-induced precipitations, considering both...
Due to their advantageous properties, tungsten (W) and steels are the main candidates for plasma-facing and structural materials for future fusion reactors. However, exposure to 14 MeV neutrons from D-T fusion reaction in nuclear environment will introduce significant displacement damage, altering the crystal structure of the materials and affecting their physical properties. To examine...
Tungsten has been selected as the divertor material for ITER and is also considered for the first wall in fusion reactors due to its exceptional properties, including a high melting point, excellent thermal conductivity, low thermal expansion, high strength at elevated temperatures, and a high sputtering threshold energy. In these environments, tungsten will be exposed to neutron irradiation,...
Hydrogen adsorption and absorption at solid surfaces is a prototype surface reaction, where fundamental concepts of gas-surface interaction are embodied. As such, hydrogen interaction with solid surfaces has been extensively studied in the surface science community [1]. To investigate the behavior of hydrogen at surfaces, our group has developed nuclear reaction analysis (NRA), which allows us...
With tungsten (W)-copper (Cu) bonding potentially used in the plasma-facing components (PFCs) in fusion devices, hydrogen isotope (HI) transport through the W/Cu interface is a key concern for tritium self-sustainment and operation safety.
To investigate HI permeation through W/Cu interface, a series of low-energy deuterium (D) plasma-driven permeation (PDP) experiments were performed on...
Molecular dynamics (MD) is a powerful materials simulation approach whose accuracy is limited by the interatomic potential (IAP). The quest for improved accuracy has resulted in a decades-long growth in the complexity of IAPs, many of which are implemented in the LAMMPS MD code.[1] Traditional physics-based IAPs are now being rapidly supplanted by machine-learning potentials (MLIAPs). The SNAP...
Classical molecular dynamics (MD) is in principle an ideal tool to investigate the long-time evolution of materials in extreme environments, as ab initio-based MD simulations remain limited to very short time. While modern machine learning MD potentials report errors on the order 1 meV/atom, these errors are only typical of configurations that are similar to those found in the training set...
In fusion reactors, the control of plasma parameters in the edge plasma plays a crucial role in maintaining high core plasma performance and achieving efficient burning conditions. The edge plasma is in direct contact with the reactor wall, where complex interactions occur due to plasma irradiation. This interaction leads to the release of neutral hydrogen atoms and molecules from the wall...
Universal interatomic potentials parameterize the interactions between all chemical elements in the periodic table simultaneously. In my talk I will introduce the Graph Atomic Cluster Expansion (GRACE). GRACE builds on a complete set of graph basis functions and can be viewed to generalize equivariant message passing neural networks and other machine learning interatomic potentials. I will...
Developing materials resistant to neutron irradiation is one of the key challenges in fusion energy applications. Due to the lack of fusion neutron sources for irradiation experiments, computational simulations provide valuable information and references for addressing such challenges. Multiscale simulation methods through a hierarchical, information-passing paradigm are often employed to...
The molecular dynamics (MD) simulations of successive collision cascades (SCC) within a single simulation domain have recently been employed to predict radiation damage at varying dpa levels [1,2]. We carry out SCC simulations with different primary knock-on atoms (PKAs) and interatomic potentials (IPs)โnamely, traditional EAM and machine learning potentials (MLIPs). Since dpa serves as the...
Tungsten (W) is considered as a promising plasma-facing material for future fusion reactors. W components will be subjected to an intense flux of 14 MeV neutrons. This will result in the production of displacement damage and material transmutation. W components will operate at elevated temperatures (673-1300 K), which will favor the formation of irradiation-induced voids. These voids will act...
Temperature plays a critical role in the behavior of deuterium (D) in tungsten (W), a key material for plasma-facing components in fusion reactors. This study investigates the effects of temperature variation on D retention, surface blistering, and defect evolution in W. Two sets of temperature rising (TR) and temperature declining (TD) irradiation experiments were conducted in the temperature...
Tungsten will be used as the plasma facing material in fusion reactors, and will be subjected to irradiation, which will affect its properties. Fusion fuels, such as hydrogen isotopes, will be implanted into the material, which will affect the material properties and be a problem as radioactive tritium is retained. Experimentally it has been seen that having deuterium present during...
Tungsten, a candidate for nuclear fusion reactor armour, is susceptible to helium contamination. Such impurities are believed to interfere with the movement of screw dislocations, which typically propagate by nucleation and migration of kink pairs. Modelling this requires large simulations cells that are well beyond the limits of density functional theory, with a few heroic exceptions [1]....
