ABSTRACT
The photoacoustic effect is presented as a suitable experimental technique to determine thermal diffusivities and hence thermal conductivities of gases at moderate pressure. The theory is developed and an experimental setup is described. Measurements were done in the temperature range from 253 K to 373 K and in the pressure range from 0.01 M P a to 0.1 M P a. Errors caused by damped harmonic oscillations in the photoacoustic cell - so called Helmholtz oscillations - are corrected. A comparison of measurements for gaseous argon with recommended data leads to an estimated accuracy of ± 0.5 %.
