Ultrasonic attenuation in pure water: Comparison between through-transmission and pulse-echo techniques

Abstract

The ultrasonic attenuation has been estimated by a variety of methods. However, even if the techniques are accurate, the measurement of this parameter is very difficult because it depends on the conditions of the experiment (frequency, temperature, internal structure of the specimen, artifacts, etc.). Attenuation measurements in tri-distilled and degasified water were made by pulse-echo and through-transmission techniques at 1 MHz, 25°C and 19.7°C. Besides the techniques, a micrometer and a scanner system were used to make the displacements. The attenuation coefficient α is been approximated by the exponential behavior of the ultrasonic signal record along 20 cm. Performance of ultrasound in water was analyzed in two zones, near and far lengths. At near zone, α is highly variant, while at far zone, an average α = -0.04417 np/cm is obtained. The purpose of this work is to compare the through-transmission and pulse-echo techniques to obtain the attenuation coefficient in pure water by the approximation of its exponential behavior.