【摘要】 基于减少光电子的要求 ,BEPCⅡ真空管道采用antechamber结构 ,TE模截止频率可能低于BPM信号处理频率 5 0 0MHz .本文主要模拟研究TE10 模对位置测量的影响 ,发现TE10 模截止频率低于 5 0 0MHz时 ,将带来束流位置测量误差 10 .1μm ;改变狭缝长度 ,在TE10 模截止频率高于 5 0 0MHz时 ,测量误差将在可以接受的范围内 .同时 ,模拟研究了BPM尾场对束流的影响 ,计算了相应尾场阻抗更多还原

【Abstract】 Considering the effect of photoelectron, BEPCⅡ′s beam position monitor (BPM) uses antechamber structure. The cut-off frequency of TE mode is maybe lower than the BPM signal processing frequency 500MHz. The power of TE mode will result in beam position measurement error. With monitoring the antechamber’s TE mode power amplitude and calculating the transmission of TE mode power to BPM’s electrodes, we can calculate the error of position measurement caused by TE mode. We found that the error is beyond the acceptance when the cut-off frequency of TE 10 mode is lower than 500MHz. By changing the slot length, the cut-off frequency is higher than 500MHz and the error could be accepted. At last the effect of the wakefield to the beam has been simulated and the longitudinal impedance of wakefield has been calculated.更多还原