Bunch-by-bunch beam current and lifetime measurement with interleaved sampling at HLS

To achieve high-precision, bunch-by-bunch beam cur-rent and lifetime measurements at the Hefei Light Source (HLS), we developed a beam diagnostics system based on interleaved sampling technology, achieving an equivalent sampling rate of 6.5 GHz. In single-bunch mode, amplitude extraction via cross-correlation with a single response function yieds a turn-by-turn current relative resolution of 0.12%. By averaging over 200 turns, the resolution is improved to 0.04% at a 23 kHz data refresh rate, enabling fast and accurate lifetime calculations. However, in multi-bunch high-current mode, large longitudinal oscillations degrade the accura-cy of amplitude extraction when using a fixed-response function. We propose an integration method to mitigate the effects of bunch length and phase oscillations on beam current measurements. The method and experi-mental results provide a practical solution for machines exhibiting large longitudinal oscillations, such as HLS.