Absorption of sound in gases between 10 and 25 MHz: argon

A measurement system has been developed to investigate the technology required for high-power gas-coupled ultrasonics and the phenomenology of finite-amplitude of ultrasonic waves in gases at high frequencies (>10 MHz) and pressures up to 10 MPa (100 bar). Results of measurements of compression wave absorption and velocity in argon between 10 and 25 MHz, with various combinations of pressure, temperature and power level are presented. For small-amplitude waves, the resulting data are in good agreement with those calculated using ideal gas equations and fundamental thermophysical gas constants. At higher power levels, nonlinear phenomena are observed.<>