基于合肥国家同步辐射实验室(NSRL)低能量真空紫外光源的特点, 研制了耦合式刀片低能束流位置探测器, 用于在线监测波荡器辐射出的低能量真空紫外相干光源的稳定性。探测器采用V型耦合式刀片作为探针, 基于错位安装、倾斜嵌入被测光束边缘和直流偏压捕集自由电子等技术有效增强光电效应, 提高探针的响应灵敏度和探测器监测精度。介绍了耦合式刀片低能束流位置探测器的结构特点、探测原理和性能测试, 在线监测了NSRL波荡器光源的稳定性, 获得了一系列有价值的试验数据。结果表明：该探测器能完成NSRL-0.8GeV低能储存环上插入件光源的在线监测, 满足对改造后的新光源各插入件辐射光束位置稳定监测的要求。

On the basis of characteristics of the VUV light source at National Synchrotron Radiation Laboratory(NSRL), a V-coupling-blade Beam Position Monitor (V-BPM) is developed to detect the stability of the low energy beam radiated from an undulator. The monitor is composed of two pairs of V-coupling-blades made of molybdenum. To increase the photoemission currents and improve the response sensitivity of the probe, both V-coupling-blades are inserted in the beam edges at an angle of 10° in horizontal and offset each other along the beam direction, and the bias of ~300 V is adapted to collect the photon-electronics more effectively. It describes the principles and structure features of the V-BPM and discusses the results of performance tests. A V-BPM is mounted on the undulator beamline at the NSRL to monitor the stability of the light source and a series of data on the tests are obtained. The results show that the V-BPM can test the radiation beam position from the new undulator in the improved NSRL in real time and obtained data meet the requirements of monitoring photon-beam stability.