A study of pickup and signal processing for HLS-II bunch current measurement system

TL;DR

This paper evaluates pickup types and signal processing methods to improve the accuracy of bunch current measurement in the HLS-II storage ring, addressing the impact of bunch length variation on measurement precision.

Contribution

It provides a comparative analysis of strip-line and button pickups with different signal processing techniques to mitigate bunch length effects in current measurement.

Findings

Strip-line pickup with integral processing reduces influence of bunch length change to less than 2%.

Button pickup with peak value processing shows about 27% calibration factor variation with 19% bunch length change.

The study offers a practical solution for accurate bunch current measurement at HLS-II.

Abstract

For the HLS-II bunch current measurement system, in order to obtain the absolute value of bunch current, the calibration factor should be determined by using DCCT. At the HLS storage ring, the stretch effect of bunch length is observed and the change rate is about 19% when the bunch current decays over time and this will affect the performance of bunch current detection. To overcome the bunch stretch influence in the HLS-II bunch current measurement, an evaluation about pickup type and signal processing is carried out. Strip-line pickup and button pickup are selectable, and the theoretical analysis and demonstration experiment are performed to find out an acceptable solution for the bunch current measurement system at HLS-II. The experimental data analysis shows that the normalized calibration factor will change by about 27% when the bunch length change by about 19% if using the button pickup and processing by peak value of bunch signal, the influence will be reduced to less 2% if adopting the strip-line pickup and integral.