Offline calibration of stripline beam position monitor for HLS Ⅱ
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摘要: 针对合肥光源二期改造工程设计了一条带束流位置检测器(BPM), 用于储存环中束流参数在线测量。对条带BPM进行了位置信号的离线标定,采用差比和法和对数比法进行计算,获得了灵敏度系数、映射图和拟合经验多项式,发现采用对数比法得到的灵敏度大小和线性范围好于差比和法。对和信号进行离线标定,发现和信号相对中心位置处的归一化值在(-5 mm, -5 mm)到(5 mm, 5 mm)范围内变化不超过6%。该条带BPM也用来测量合肥光源储存环上束团横向四极振荡,所以需对横向四极分量进行标定。采用二维网格结构高斯加权法模拟高斯束团,使用差比和法进行计算,并将测量结果与模拟结果比较,发现横向四极分量随 (x2-y2)线性变化的灵敏度与模拟结果相同,均为0.001 1 mm-2。得到的拟合经验公式用于在线测量。Abstract: A stripline beam position monitor(BPM) was designed for HLS Ⅱupgraded and used to measure beam parameter in the HLS storage ring. Position signal was offline calibrated using the difference/sum and log-ratio methods. Sensitivities, mapping figures and experienced fitting polynomials were acquired. The results showed that the sensitivities and linear range using logratio method were bigger than those using difference/sum method. The sum signal was offline calibrated and the result showed that the variety of normalized sum signal relative to the sum signal at the stripline BPM center was no more than 6 % in the range of (-5 mm, -5 mm) to (5 mm, 5 mm). The stripline BPM will be also used to measure the transverse quadrupole oscillation in the HLS storage ring, so calibrating transverse quadrupole component is needed. The Gaussian weighted method of a two-dimensional grid structure was used to simulate the Gaussian bunch and the difference/sum method was applied to calculate transverse quadrupole component. The measurement result was compared with the simulation result. The result showed that the sensitivity of the transverse quadrupole component varying with (x2-y2) by offline method was the same as simulation result and sensitivity was 0.001 1 mm-2. Experienced fitting polynomial was calculated to be used for the future online measurement.
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