基于嵌入式系统的发射度测量仪

Development of an emittance measurement instrument based on embedded system

基于嵌入式系统的发射度测量仪采用法拉第筒测量方法,数据采样率达到200kHz,设计有7个不同的电流采样量程。讨论了发射度测量仪的系统构成和工作原理,详细介绍了其数据采集系统的设计与制作。通过选用高速、低噪声的集成电路芯片并组合适当大小、适宜材料的电阻和电容构建模拟链路,贯穿于整个模拟链路的滤波设计和低噪声的模拟电源技术及屏蔽防护技术都保证了低噪声采集电路的实现。实验测试表明:在量程为10nA时,该测量仪测量精度为1.47%,量程1 000nA时则达到0.32%;采样20kHz的正弦波信号失真度为6.5dB;运动精度为1.25μm时,运动速度最高3.125mm/s。

An emittance measurement instrument based on embedded system was introduced.The instrument was based on slit-wire method.It had seven different measurement ranges,and its data sampling rate was up to 200 kHz.The system construction and working principle were discussed.The design and production of the data acquisition system were also discussed.The analog signal circuit was established by using high-speed,low-noise integrated chips,along with appropriate resistors and capacitors.The filters in every stage,the low-noise power supply technology and the shielding technology insure the realization of a low-noise data acquisition circuit.The results of tests show that the acquisition accuracy is 1.47% at the measurement range of 10 nA,and up to 0.32% at the range of 1 μA.The harmonic distortion is 6.5 dB when a sine wave is sampled with the frequency of 20 kHz.The fastest movement speed is 3.125 mm/s at the movement accuracy of 1.25 μm.