Ultrasonic propagation in various gases at elevated pressures

Ultrasonic propagation has been studied in air, helium (He) and carbon dioxide (CO 2 ) at pressures of up to 2 bar. The experiments were carried out using an inexpensive pressure chamber, manufactured from commercially available components. Accurate measurements of ultrasonic attenuation were performed, taking into account the diffraction effects of the transducers. It is also shown that ultrasonic transmission through solid materials, such as cardboard, can be enhanced at high pressures, using capacitive transducers whose performance is enhanced under such conditions.