High Sensitive Detection for SF6 Decomposition Component of H2S Based on Laser Photoacoustic Spectroscopy

H2S is one of characteristic components for discharge faults diagnosis in the SF6 gas insulated device. Due to the small absorption coefficient of H2S gas in the near-infrared band, the detection sensitivity is difficult to improve with traditional optical detection methods. To solve this problem, we propose an enhanced laser photoacoustic detection method, which combines the technologies of high-power fiber laser amplifying, resonant laser photoacoustic spectroscopy, wavelength modulation spectroscopy, and second-harmonic detection, for high sensitive detection of H2S decomposed by SF6. By cascading a near-infrared tunable narrow linewidth distributed feedback laser diode with a high saturation output power erbium doped fiber amplifier as the photoacoustic excitation light source, we develop a high-sensitivity laser photoacoustic spectroscopic system for trace H2S gas detection. The results show that the detection limit in the background of SF6 is achieved to be 1.5 x 10(-8) with the measurement time of 100 s.