Research on Crosstalk of High-Voltage Signal Transmission Cables for Quench Detection System of Chinese Next-Generation Fusion Device

The quench detection system for next-generation fusion device of China face enormous challenges, as their magnet systems are characterized by significantly higher stored energy and faster discharge rates than those in predecessors, such as EAST and KSTAR. During both the plasma discharge phase and the superconducting magnet quench current discharge phase, rapid current changes induce high and dynamically varying voltages on magnets, particularly in the central solenoid and poloidal field coils, where kilovolt-level inductive voltages can arise. These high-voltage signals can appear on the quench detection signal cables connected to the magnets, leading to capacitive coupling crosstalk between these cables within the same cable tray. Such crosstalk severely interferes with the quench detection signals, compromising the accurate identification of magnet quenches. This can potentially lead to either false quench detection or a failure in quench detection. To address this, this article presents a systematic investigation into the crosstalk phenomenon. It begins by characterizing the properties of quench detection signals. Subsequently, an electrical circuit model for signal cable crosstalk is established, and the influencing factors of crosstalk are analyzed. Finally, the model is validated through a dedicated experiment, whose results are used to predict crosstalk levels in the operational environment and to propose effective mitigation strategies to ensure robust quench detection.