Influence of the duct shape on the Q-factor of a photoacoustic Helmholtz resonator

Abstract

The use of a Helmholtz resonator as a photoacoustic cell has many advantages. Its main drawback in high-sensitivity photoacoustic measurements is the relatively low values of Q-factors of such cells. One of the important loss sources which limit the quality factor of photoacoustic Helmholtz resonators is the rapid change of the cross section at the cavity-duct boundaries. This paper presents a design of a cell in which the shape of the duct was modified in such a way that the cross-section change is more gradual. A presented comparison of measurements of the Q-factors shows clearly that the Q-factor of the cell can be improved by almost a factor of two by such a modification of the duct shape. © The Author(s) 2010.