A New Analog Integrator for Magnetic Diagnostics on EAST

A new kind of analog integrator has been developed for Magnetic diagnostics (MDs) on Experimental Advanced Superconducting Tokamak (EAST). While previous analog integrators are single-ended input, which has low common mode rejection ration (CMRR), a kind of difference integrator is introduced which has the same structure as the standard difference amplifier. The linear drift compensation method is used for determining the effective drift slope, then the plasma control system (PCS) use the drift slope to rectify the integration signal in real time. To improve the maintainability and testability of the integrator system, a new integrator controller was developed, which uses an ARM micro-controller and the lightweight IP protocol stack to realize the network control. The tests show that the upgraded integrator works well, its CMRR is high up to 125 dB when the common voltage is 1.5 V, and the processed integration drift is about 200 uVs /1000 s, which is much better than the previous integrator.