School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, Liaoning 116024, China.
Electric Power Research Institute, Net Anhui Electric Power Co., Ltd, Hefei, Anhui 230601, China.
Anal Chem. 2023 May 30;95(21):8214-8222. doi: 10.1021/acs.analchem.3c00003. Epub 2023 May 16.
We designed and implemented a photoacoustic (PA) sensor for HS detection in SF background gas based on a multi-pass differential photoacoustic cell (MDPC) and a near-infrared distributed feedback (DFB) laser. In the MDPC apparatus, two resonators with identical geometric parameters were vertically and symmetrically embedded. The differential processing algorithm of two phase-reversed signals realized the effective enhancement of the PA signal and suppressed the flow noise in the dynamic sampling process. In addition, the λ/4 buffer chamber in the MDPC was utilized as a muffler to further reduce the flow noise and realize the dynamic detection of HS. The collimated excitation light was reflected 30 times in a multi-pass structure constituted of two gold-plated concave mirrors, and an absorption path length of 4.92 m was achieved. Due to the high gas density of SF, the relationship between the signal-to-noise ratio (SNR) and the gas flow was different between SF and N background gases. The maximum flow rate of the characteristic gas components detected in the SF background is 150 standard cubic centimeters per minute (SCCM), which is lower than 350 SCCM in N. The linearity property was analyzed, and the results show that the sensitivity of the sensor to HS in the SF background was 27.3 μV/ppm. With the structure, parameters, temperature, gas flow, and natural frequency of the MDPC been optimized, a minimum detection limit (MDL) of 11 ppb was reached with an averaging time of 1000 s, which furnished an effective preventive implement for the safe operation of gas insulation equipment.
我们设计并实现了一种基于多通差分光声池（MDPC）和近红外分布式反馈（DFB）激光的 SF 背景气体中 HS 检测的光声（PA）传感器。在 MDPC 仪器中，两个具有相同几何参数的谐振器垂直且对称地嵌入。两个相位反转信号的差分处理算法实现了 PA 信号的有效增强，并在动态采样过程中抑制了流动噪声。此外，MDPC 中的 λ/4 缓冲室被用作消音器，以进一步降低流动噪声并实现 HS 的动态检测。准直激发光在由两个镀金凹面镜构成的多通结构中反射 30 次，实现了 4.92 米的吸收路径长度。由于 SF 的气体密度高，SNR 与气体流量之间的关系在 SF 和 N 背景气体之间有所不同。在 SF 背景中检测到的特征气体成分的最大流速为 150 标准立方厘米每分钟（SCCM），低于 N 中的 350 SCCM。对线性度特性进行了分析，结果表明，传感器对 SF 背景中 HS 的灵敏度为 27.3 μV/ppm。通过优化 MDPC 的结构、参数、温度、气体流量和自然频率，在平均时间为 1000 s 的情况下，达到了 11 ppb 的最小检测限（MDL），为气体绝缘设备的安全运行提供了有效的预防手段。
