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Description
To meet the requirements of the Hefei Advanced Light Facility (HALF) for high-speed and high-precision online measurement of beam current and lifetime, this paper presents a measurement system based on an FPGA and dual-ADC architecture. The system employs an FPGA evaluation board with dual FMC interfaces as its core, integrating a high-precision ADC (2 MHz, 24-bit) and a high-speed ADC (1 GHz, 14-bit) to achieve synchronous data acquisition. For average current measurement, an averaging and downsampling algorithm is utilized to achieve a resolution of 2 $\mu$A at a 100 Hz data output rate, based on which the average beam lifetime is calculated. For bunch-by-bunch beam current measurement, a two-point peak-finding algorithm is implemented to accurately extract peak signals. The system performs real-time online calibration of the bunch-by-bunch beam current using the high-precision average current, enabling the acquisition of absolute bunch-by-bunch beam current values and the subsequent calculation of bunch-by-bunch beam lifetimes. Finally, all measurement data are transmitted to an ARM-based embedded Linux system and published to the accelerator control network via an EPICS IOC. This system architecture provides reliable support for high-precision beam diagnostics and the stable operation of HALF.
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