Browsing by Author "Zhang, Xueshi"

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    Compact QEPAS humidity sensor in SF6 buffer gas for high-voltage gas power systems
    (Elsevier, 2022) Yin, Xukun; Dong, Lei; Wu, Hongpeng; Gao, Miao; Zhang, Le; Zhang, Xueshi; Liu, Lixian; Shao, Xiaopeng; Tittel, Frank K.
    In SF6 insulated high-voltage gas power systems, H2O is the most problematic impurity which not only decreases insulation performance but also creates an acidic atmosphere that promotes corrosion. Corrosion damages electrical equipment and leads to leaks, which pose serious safety hazards to people and the environment. A QEPAS-based sensor system for the sub-ppm level H2O detection in SF6 buffer gas was developed by use of a near-infrared commercial DFB diode laser. Since the specific physical constants of SF6 are strongly different from that of N2 or air, the resonant frequency and Q-factor of the bare quartz tuning fork (QTF) had changed to 32,763 Hz and 4173, respectively. The optimal vertical detection position was 1.2 mm far from the QTF opening. After the experimental optimization of acoustic micro-resonator (AmR) parameters, gas pressures, and modulation depths, a detection limit of 0.49 ppm was achieved for an averaging time of 1 s, which provided a powerful prevention tool for the safety monitoring in power systems.
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    Near-infrared laser photoacoustic gas sensor for simultaneous detection of CO and H2S
    (Optical Society of America, 2021) Yin, Xukun; Yin, Xukun; Gao, Miao; Miao, Ruiqi; Zhang, Le; Zhang, Xueshi; Liu, Lixian; Shao, Xiaopeng; Shao, Xiaopeng; Tittel, Frank K.
    A ppb-level H2S and CO photoacoustic spectroscopy (PAS) gas sensor was developed by using a two-stage commercial optical fiber amplifier with a full output power of 10 W. Two near-infrared diode lasers with the central wavenumbers of 6320.6 cm−1 and 6377.4 cm−1 were employed as the excitation laser source. A time-division multiplexing method was used to simultaneously detect CO and H2S with an optical switch. A dual-resonator structural photoacoustic cell (PAC) was theoretically simulated and designed with a finite element analysis. A µV level background noise was achieved with the differential and symmetrical PAC. The performance of the multi-component sensor was evaluated after the optimization of frequency, pressure and modulation depth. The minimum detection limits of 31.7 ppb and 342.7 ppb were obtained for H2S and CO at atmospheric pressure.