Double-channel sensors for high precision measurement of methane based on a dual-path Herriott cell

• Published in: Analyst (London) Vol. 149; no. 22; pp. 5527 - 5534
• Main Authors: Ma, Hongliang, Wang, Shiqi, Wang, Gaoxuan, Zhang, Qilei, Zha, Shenlong, Cai, Xueyuan, Li, Lingli, Pan, Pan, Liu, Qiang, Zhan, Shengbao
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 04.11.2024
• Subjects: Configuration management; Methane; Sensors; Time measurement
• ISSN: 0003-2654; 1364-5528; 1364-5528
• DOI: 10.1039/d4an01107d

A double-channel methane (CH ) sensor was developed using a dual-pass multipass cell (DP-MPC) and a novel method that combines averaging dual-channel concentration signals with optimized detector gain configuration. This DP-MPC features two input/output coupling holes, resulting in absorption path lengths of approximately 95.8 m and 35.8 m, respectively. By optimizing the photodetector gain configuration and averaging the dual-channel concentration signals, the detection performance of the sensor was further enhanced. Allan deviation analysis indicated that after optimizing the detector gain, the measurement precision after dual-channel averaging reaches 21 ppb with an integration time of 1 s at a concentration of 2 ppm CH , which is approximately 1.4 times higher than the measurement precision of the long-path channel (31 ppb) and short-path channel (30 ppb). The time required to achieve a measurement precision of 21 ppb is 2.4 s for the long-path channel and 2.1 s for the short-path channel. The response speed of the dual-channel averaging is approximately 2 times that of any single channel. Meanwhile, the sensor demonstrated its stability and reliability through continuous outdoor atmospheric CH measurements.