Structure Design of Electromagnetic Shield on High Voltage Instrumentation Cables for the Fusion Reactor

Abstract

The ITER superconducting magnet measurement cable is an important route for the signals transmission from the superconducting magnets system to the control system, the magnets system and instruments may release electromagnetic field (Rodriguez-Mateo and Carcagno in DDD11-9: instrumentation and controls, ITER Organization, 2012). The cable can pick up EMI radiated, which can seriously disrupt the proper operation of the instrumentation and control system, so it is crucial to acquire an reasonable electromagnetic shield structure of HV instrumentation for high efficient electromagnetic compatibility. In this paper, we study two types of shielding typically used for cables, the transfer impedance of two types shielding are very close, when the electromagnetic frequency is most concentrate in 0–30 MHz in the cable work environment, so we determine unshielded twisted pairs as inner wire group, combined with two layer braiding. Last, based on the Vance’s calculation model, drawing in MATLAB, we respectively calculate the minimum transfer impedance of two braid layer, by discussing the relationship between braiding parameters and transfer impedance, the shield structure parameters of HV instrumentation cables are determined.