束流变压器的基线漂移效应研究

束流变压器（BCT）在频域表现为带通特性，其低频截止特性会引起基线漂移现象，本文使用高通滤波器模型对低频截止特性对单束团和连续束团的影响进行了分析。采用基线操纵和一次谐波算法两种方法进行了基线修复，使BCT测量高重复频率连续束团的相对误差由20%下降至3%以内。

Research of Baseline Shift of Beam Current Transformer

The beam current transformer (BCT) shows bandpass characteristic in the frequency domain, and the low-frequency cut-off character is the reason of baseline shift. In this paper, the analysis of the baseline shift for single bunch and continuous bunches was presented using high pass filter model. Two methods as baseline manipulation and primary harmonic algorithm were used to do baseline restoration. And the measurement relative error of the high frequency continuous bunches is reduced from 20% to less than 3%.