Quantitative Finite Element Modelling of Compact Photoacoustic Gas Sensors

We report on the demonstration of quantitative simulation of compact photoacoustic cells signals. The finite element method is used to calculate the response of differential Helmholtz resonator cells of two different sizes. Simulated quality factors and resonance frequencies are compared with experimental ones. Taking account of the gas sample absorption coefficient and the laser intensity, cell constants are also evaluated and compared to experimental values showing a very good agreement. For compact sensors, where sub-millimeter features are present, the resolution of the pressure acoustics equation is not sufficient to reproduce experimental results and a viscothermal model must be used.