Speaker
Description
The CSNS-II upgrade will raise the RCS beam power from about 180 kW to 800 kW, imposing stringent requirements on the BPM electronics, in particular a wide input dynamic range and high position accuracy. The system comprises four local stations, each with an MTCA.4 crate hosting eight BPM channels and one timing board; each channel consists of an RTM board and an AMC board. To cover the wide pickup-signal range of about 54 dB (0.16 Vpp at injection to 80 Vpp at extraction), the RTM front-end employs a four-stage attenuation-switching scheme providing up to 34 dB of attenuation, conditioning the 0–80 Vpp input into the ADC dynamic range. The AMC board, based on a Xilinx Zynq SoC with a 16-bit, 125 MSPS ADC, implements the STD algorithm and provides raw-data, turn-by-turn (TBT) and closed-orbit (COD) modes. Control and data-acquisition software was developed based on EPICS. Laboratory tests show an SNR above 73 dB, an isolation above 85 dB, and an ADC dynamic range of ±1 Vrms. The bunch-by-bunch position resolution is better than 50 µm (0.05% R) in both the x and y planes, and the closed-orbit resolution is better than 5 µm, for signal amplitudes above 0.6 Vpp. In October 2026, eight complete BPM systems were batch-produced and successfully deployed for operation.
