开关触发延迟时间和抖动测量的不确定度分析

Uncertainty in delay and jitter measurement of laser-triggered switch

为明确脉冲功率装置开关触发延迟时间和抖动测量的可信度,进行了不确定度评定。使用拟合的线性关系式结合示波器水平分辨力导致的不确定度建立开关延迟时间不确定度的数学模型;根据抖动的定义建立抖动的测量不确定度数学模型。两者均按B类不确定度评定。以相关实验数据为基础计算了各个不确定度分量、合成标准不确定度以及扩展不确定度。按工程测量要求置信概率为95%,取包含因子为2,可得初级实验平台(PTS)单路样机激光触发开关触发延迟时间测量的扩展不确定度为0.38 ns;抖动测量的扩展不确定度为0.13 ns。延迟时间和抖动测量结果的不确定度满足实验分析的要求。

The uncertainty in delay and jitter measurement has been evaluated for the laser-triggered switch in the Z-pinch primary test stand （PTS） prototype module. The delay is defined as the time difference between the 10% amplitude points in rise edges of laser signal and dI/dt of the switch. A line can be fitted from the rise edge of the dI/dt waveform, whose slope deter- mines the inflUence of amplitude measurement＇s uncertainty on delay measurement＇s uncertainty. Thus the frequency response un- certainty of the measure system is included in the linear function, and the math model of delay uncertainty is founded from the fin- ear function modified with the uncertainty from the time resolution of the digital oscillograph. The model of jitter uncertainty is founded from the definition of jitter, and the jitter uncertainty is expressed hy the function of delay uncertainty. Both two standard uncertainty are determined by Type B evaluation. The expanded uncertainties of the switch＇s delay and jitter are 0.38 ns and 0.13 ns, respectively, for the PTS, when the coverage factor is 2 and the confidence probability is 95%, satisfying the experiment requirements.