New Understanding of Neutron Damage in Thyristors Boosts Fusion Reactor Safety

Sydney, Australia (SPX) Aug 05, 2024 - A research team led by Associate Prof. LI Hua from the Institute of Plasma Physics at the Hefei Institutes of Physical Science, Chinese Academy of Sciences, along with Dr. TONG Wei's team from Hefei University of Technology, has uncovered the mechanisms of neutron irradiation damage in high-power thyristors used in quench protection systems.

Their findings were published in Nuclear Science and Techniques.

High-power semiconductors, particularly thyristors, are crucial components in the power supply systems of Tokamak fusion devices. Critical power equipment must be situated close to the superconducting Tokamak to ensure the reactor's safety. Neutrons produced by Deuterium-Tritium fusion reactions can alter the material properties of p-n junctions, making it essential to study how neutron irradiation affects thyristors' electrical performance.

The study established a relationship between the physical and electrical characteristics of high-power thyristors under 14 MeV neutron irradiation. Researchers developed a mathematical model considering key thyristor parameters such as carrier lifetime, mobility, reverse/forward blocking voltage, and reverse recovery charge. Simulations and experiments were conducted to reveal the degradation of thyristor electrical parameters due to neutron irradiation.

Additionally, the research examined how performance changes in irradiated thyristors impact the protection system's security. Results showed that increased leakage current in irradiated thyristors could lead to protection system failures. This performance degradation raises the risk of damage to the superconducting Tokamak.

"Our research provided basis support and further study directions for improving the reliability of fusion reactor protection system," said LI Hua.

Research Report:Neutron irradiation influence on high-power thyristor device under fusion environment