Upgrade of poloidal field coils current measurement system on Experimental Advanced Superconducting Tokamak

摘要

Measuring poloidal field (PF) current with a high accuracy is a basic requirement for the operation of a tokamak. A fiber optic current measurement system consisting of 12 fiber optic current sensor (FOCS) was installed on the Experimental Advanced Superconducting Tokamak (EAST) PF busbars in 2018. Before installation, the FOCS sensor heads were calibrated for a temperature range between -5 degrees C and 55 degrees C to meet the PF busbars current measurement accuracy requirement (0.4%). To reduce the sensor head magnetic crosstalk, a model has been developed and validated for FOCS sensor heads. When used to sense EAST PF busbar currents during experiments, the FOCS showed excellent performance. Compared with the Rogowski coil, there was no time-dependent drift or magnetic crosstalk in the FOCS output, and the noise of the FOCS was smaller than the Rogowski coil.