Method for solving bunch head-tail overlapping in HLS-II using a new trigger scanning module of streak-camera measurement system

Abstract

This study proposed a trigger scanning module for a streak camera to overcome head–tail overlapping of bunch to achieve absolute bunch length monitoring based on the unique machine properties of the Hefei Light Source-II (HLS-II). Furthermore, precise measurement of longitudinal bunch characteristic parameters and study of longitudinal beam dynamics is crucial, and this significantly contributes for observing longitudinal bunch behavior and evolution associated with current potential-well distortion and microwave instability. First, the scanning module is calibrated thoroughly to test its performance and applicability. Afterward, the module is applied to measure the dependence of bunch length on current under single-bunch operation. Moreover, potential-well distortion and bunch lengthening are observed. Results showed that the designed trigger scanning module is appropriate for the exploration of the physical mechanism of single-bunch beam behavior, which is crucial for the investigation of bunch characteristics and beam instability in storage ring light sources.