Abstract：Real-time gas detection is of great significance in manyfields, such as petrochemical industry, modern industry, environment, medical diagnosis, transformers. Photoacoustic spectroscopy (PAS) gas detection technology is a gas detection technology based on the PA effect. It has been widely used in tracegas detection because of its high detection sensitivity, high selectivity, high resolution, wide detection range and real-time monitoring. The PA cell is the most important componentof the PAS system.And the sensitivity and resolution of the system are directly affected by PA cell. The standard cylindrical structure of the resonance the PA cell is a common choice, and the detection sensitivity and resolution of the system are mainly improved by the microphone. In this paper, a high-sensitivity ellipsoidal resonant photoacoustic cell is proposed for the first time. Combining with the theory of gas thermodynamics and acoustics, the finite element method of ellipsoidal photoacoustic cell and traditional cylindrical photoacoustic cell is analyzed by COMSOL software, its acoustic feature model is established. The acoustic characteristics of the photoacoustic cell,such as resonance frequency, the sound pressure distribution in the cavity of the photoacoustic cell, and the acoustic pressure level are simulated. The relationship between resonance frequency, sound pressure, the size of ellipsoidal, cylindrical photoacoustic cell and the length and center radius of the ellipsoidal photoacoustic cell is simulated. The optimal length and center radius ofthe ellipsoidal photoacoustic cell is 100 and 5 mm, respectively. Compared with a conventional cylindrical photoacoustic cell, the resonant frequency of the ellipsoidal photoacoustic cell is 1 340 Hz and the cylindrical photoacoustic cell is 1 650 Hz. The sound pressure signal generated in the resonance state is about 5.01×10-5 Pa and the cylindrical photoacoustic cell is 5.7×10-6 Pa. The sound pressure level is 11 dB and the cylindrical photoacoustic cell is -13.9 dB. The Q-factor is 70 and the cylindrical photoacoustic cell is 66. The results show that the resonant frequency of the ellipsoidal photoacoustic cell is less than that of the cylindrical photoacoustic cell, and the maximum sound pressure signal is about 9 times that of the same size cylindrical resonant photoacoustic cell, and the sound pressure level is increased from -13.9 to 11 dB. The ellipsoidal resonant photoacoustic cell has small volume, large acoustic pressure signal, high detection sensitivity, and the performance of the photoacoustic cell has been improved significantly. This structurecan improve the sensitivity of photoacoustic spectroscopy for the detection of trace gases.
