New beam intensity measurement system for HLSⅡ injector

The upgrade project of HLSⅡ is almost finished and the new injector has achieved the goal of full energy injection. To satisfy the need of measuring the new injector beam intensity, a beam intensity measurement (BIM) system is designed, which has 3 fast current transformers (FCT) and 2 integrating current transformers (ICT) installed in the vacuum chamber to non-destructively and real-timely measure beam current and beam charge. To acquire beam parameters accurately, the article elaborates the on-line and off-line calibration method of long transmission coaxial cable. Then two low noise pre-amplifiers used to amplify the output signal of ICT to improve SNR are designed and appropriate algorithms of reducing the low frequency harmonic noise and kicker noise in software are proposed. In the end, some on-line experiment results are presented, which show that beam transmission efficiency is about 27.4% and injection efficiency is approximately 44.3%.