粒子加速器由于受地基振动、环境温度、热效应等因素的影响,导致束流位置探头(BPM)所在真空盒的机械中心相对四极铁磁中心的漂移较大,因此很难提高束流轨道的绝对测量精度。探索利用电容式探头实时检测该漂移量的方法。首先分析了电容式探头的测量原理,并设计了轨道振动同步诊断方案,然后设计了专用探头,并利用数据采集设备对探头的线性度、精度和频率响应进行实验室测试。结果显示电容式探头能检测到2μm的相对位移,且可有效检测300Hz以下的振动频率,可用于束流轨道与相关环境参数的同步诊断。 Due to the influence of ground vibration, ambient temperature and thermal effect, the particle accelerator has a large drift of the mechanical center of the vacuum box where the beam position probe (BPM) resides relative to the quadrupole magnetic center, so it is difficult to increase the absolute orbit of the beam orbit measurement accuracy. Explore the use of capacitive probe real-time detection of the amount of drift. First of all, the principle of capacitance probe is analyzed, and the synchronous diagnosis scheme of orbital vibration is designed. Then the special probe is designed and the linearity, precision and frequency response of the probe are tested by the data acquisition equipment. The results show that the capacitive probe can detect the relative displacement of 2μm, and can effectively detect the vibration frequency below 300Hz, which can be used for the synchronous diagnosis of beam orbit and related environmental parameters.