Multi-Channel Integrated Electronics Design for Bolometer Diagnostic Based on Metal Foil Detector in Tokamak Device

Abstract

In magnetic confinement nuclear fusion research, precise measurement of plasma radiative power is fundamental to understanding energy balance, physics of transportation, and ensuring safe device operation. This paper presentsmulti-channel integrated electronics, featuring an FPGA as the main controller and GbE communication, designed for metal foil detector with both positive and negative response channels for bolometer diagnostic. In this electronics design, compared to the single-channel electronics prototype developed recently, the phase shift circuit is optimized, DDS is adopted to generate carrier reference signal, and dynamic range compensation circuitry is incorporated. Within the constrained chassis, it integrates eight channels, significantly enhancing channel integration compared to the original BOLOMETER electronics on EAST. Performance testing in the electronics laboratory verified that all channels of this multi-channel integrated electronics exhibit consistent carrier excitation frequencies, with thethe maximum relative amplitude error of 0.48%. The linear correlation coefficient R-square between the electronics output and the detector output is 0.99997. At channel gain of 1000, the single-channel electronics noise is ±1.25 mV. Radiation response experiments on EAST demonstrate that the output signal trend of this electronics matched the time-varying trend of the plasma current and is similar to the output signal trend of the original BOLOMETER electronics, confirming the correctness of this electronics.