西安质子应用装置BPM设计及测试结果

西安质子应用装置(XiPAF)中能传输段设有6个束流位置探测器(BPM)用于测量束流位置及相位，要求位置和相位测量分辨率分别好于0.1 mm和1°，绝对位置测量准确度好于±0.5 mm。本文从理论上分析了纽扣型BPM位置测量分辨率与电极长度及电极张角的关系，并结合CST模拟得到最优值，设计分辨率达24.5 μm。离线测试结果表明，BPM样机的电极电容、灵敏度及电极间耦合度均与设计值相符。利用旋转法测量得到BPM样机水平和竖直方向电中心与机械中心的偏差分别为（0.04±0.05） mm和（-1.53±0.05） mm。样机安装在清华大学微型脉冲强子源（CPHS）高能传输段进行测试，测试结果表明，XiPAF BPM位置测量分辨率好于60 μm，相位测量分辨率好于0.74°，绝对位置测量准确度为±0.35 mm。该设计满足西安质子应用装置的要求。

BPM Design and Test Result of Xi’an Proton Application Facility

In the design of Xi’an Proton Application Facility (XiPAF), there are 6 beam position monitors (BPMs) installed in medium energy beam transport line to measure beam position and phase. Resolutions of position and phase measurement should be better than 0.1 mm and 1°, respectively, and accuracy of absolute position measurement should be better than ±0.5 mm. The effects of electrode length and opening angle on BPM resolution were analyzed theoretically. CST simulation was then performed to obtain the optimum parameters. The design resolution reaches 24.5 μm after optimization. The measured electrode capacitance, inter-electrode coupling and sensitivity of the BPM prototype agree with the designed value. Horizontal and vertical offsets between BPM mechanical center and electric center are （0.04±0.05） mm and （-1.53±0.05） mm, respectively, measured by a rotation method. The prototype was installed in the high energy beam transport line of Tsinghua University Compact Pulsed Hadron Source （CPHS) to test its performance. The test results show that resolutions of position and phase measured by XiPAF BPM are better than 60 μm and 0.74°, respectively, and accuracy of absolute position measurement is ±0.35 mm. The prototype satisfies the requirements of XiPAF.