Speaker
Description
Fusion magnets in deuterium-tritium based power plants will experience bombardment by high energy neutrons during operation. This is a particular severe problem for REBCO-based compact high-field fusion reactors. The fusion magnets in these devices will typically be operated at around 20 K and accumulate radiation damage at this very temperature.
We have commissioned a cryogenic ion irradiation setup at MIT, that utilizes MeV range ions as proxy for fusion neutrons to study the radiation response of REBCO tapes under fusion-relevant conditions. This test facility allows to irradiate samples at temperatures between 20 K and 300 K while analyzing in-situ changes of critical currents (Ic) and transition temperature (Tc). We used 1.2 MeV protons in fluences of up to 1021 m-2 to study the influence irradiation temperature on the degradation behavior of REBCO tapes. We found that 20 K irradiations degrade Ic and Tc at a 40 % higher rate than irradiations at 300 K. This suggests that previously determined radiation limits for fusion magnets, which were based on room-temperature irradiation results, should be re-evaluated.
We are currently building a cryogenic neutron irradiation facility next to the MIT reactor which will closely replicate the harsh fusion environment to test the degradation behavior of magnet components like REBCO tapes, stabilizers, insulation materials and sensors. First experimental results are expected by the end of 2025.
