Design and performance analysis of tuning fork for trace H2S detection
In response to the limitations of commercial standard quartz tuning forks in the application of Quartz En⁃hanced Photoacoustic Spectroscopy(QEPAS),a simulation study was conducted on the first six vibration modes of quartz tuning forks which was an acoustic detector.By optimizing the parameters of quartz tuning forks,the influence of each pa⁃rameter on resonance frequency was analyzed,and a new type of quartz tuning fork with low resonance frequency and high quality factor was designed.After testing,the resonance frequency of the tuning fork is 12.21 kHz,with a quality factor of up to 12068,and a fork clearance of 0.40 mm.Compared with the commercial standard quartz tuning fork of 30.72 kHz,the resonance frequency is reduced by 60.25％,the fork clearance is increased by a factor of 2 times,and the energy ac⁃cumulation time is increased by a factor of 1.95 times.By optimizing the length of the coupled resonant tube and the exci⁃tation position of the light source,the detection performance of the system has been improved.By using wavelength modu⁃lation and second harmonic demodulation techniques,a good linear relationship between the second harmonic signal of the system and H2S concentration was obtained.Based on QEPAS technology,the detection limit was as low as 186×10-9,achieving high sensitivity detection of H2S.
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