Quantitative estimation of acoustic streaming effects on ultrasonic power measurement

At the National Metrology Institute of Japan (NMIJ), we are developing an ultrasonic power measurement system using a radiation force balance method to establish standards for ultrasonic power in Japan. Our initial target frequency range is between 1 MHz and 20 MHz, and the power range is between 1 mW and 500 mW. Next stage, we are going to expand the power range up to higher than 20W. We have almost finished constructing the radiation force balance equipment and are now evaluating the "measurement uncertainty" for each component of the system. It is important for accurate measurements to estimate the influence of the acoustic streaming accompanying the ultrasonic power measurement. In this paper, we show the experimental results of quantitative estimation of the acoustic streaming on the ultrasonic power measurements by using two types of targets. We have tried to measure the effects of the acoustic streaming on the radiation force balance method quantitatively.