基于微型非共振腔的石英增强光声光谱用于氦气纯度分析的实验研究

实验中设计了一种基于微型非共振腔的石英增强光声光谱痕量气体传感器, 用来检测非纯氦气中的痕量氨气浓度. 该传感器采用的微型非共振腔只在空间上限制声波扩散以达到增强信号目的, 而不是像传统微型共振腔一样依靠共振效应. 如此的设计使探测小分子无机气体的光谱测声器尺寸远远小于共振腔的配置而有利于准直. 不同气压下的信号和噪声也被研究, 用来优化传感器性能. 在这种配置下和27.7 kPa的最优气压下, 获得的最佳氨气探测灵敏度为463 ppb (1σ , 1 s积分时间), 相应的归一化噪声等效吸收系数为4.3×10^-9cm^-1W/√Hz.关键词：气体传感器石英增强光声光谱音叉式石英晶振类氢气体纯度分析

Purity analysis of helium using quartz-enhanced photoacoustic spectroscopy with two non-resonant micro-tubes

A trace gas sensor, based on quartz-enhanced photoacoustic spectroscopy (QEPAS) with two non-resonant micro-tubes, was designed to detect the ammonia concentration in impure helium. Unlike the traditional micro-resonator, the non-resonant micro-tubes are used to confine the sound wave, but do not exhibit a well-defined resonant behavior. Such a design makes the dimension of the spectrophone much smaller than the micro-resonant configuration, which facilitates the optical alignment. Signal and noise, that were dependent on gas pressure, were also investigated to optimize sensor performance. With the optimal sensor parameters and the optimal gas pressure, the detection sensitivity was found to be 463 ppb (1σ , 1 s averaging time), which corresponds to the normalized absorption sensitivity of 4.3×10^-9cm^-1W/√Hz.