Simulation of Damage to Reactor and Target Materials at High Rates Due to Heavy Ion Irradiation

Studying the changes in the physical properties of materials due to radiation exposure is a crucial aspect of design for both fusion and fission reactors, as well as high power target design. One way to quantify the damage induced via radiation exposure is by using a quantity known as displacements per atom (DPA). DPA quantifies how many times, on average, each atom in a material is displaced from its lattice site due to energetic particle collisions. Using a heavy ion such as tungsten to irradiate the target allows for a much higher rate of DPA when compared to light ion beams like proton beams. Because of this, damage can occur at lower energies, avoiding the production of a radioactive target after irradiation, complicating the tear down of the experiment and post irradiation characterization. Using Monte Carlo simulations of damage we can design specific radiation configurations that produce a uniform DPA through the thickness of a thin foil, enabling the study of the physical properties of the target as the damage occurs. Additionally, if the beam and target materials are both tungsten, there will be no contamination of the target which may affect the measuring of the properties. After simulating this uniform damage, we aim to create this damage in a particle accelerator with heavy ion capabilities. The central goal of this experiment is to examine the physical properties of the material as the damage occurs. For example, both the thermal conductivity and electrical resistivity of tungsten targets can be measured in real time as a function of DPA, with resistivity offering a simple proxy for damage in future applications. These data will be useful in predicting the ability of the tungsten target to withstand high power proton beam irradiation without overheating.