A New Short Path Probe Sensing The Sound Attenuation At 10 MhZ In Situ In The Sea For The Determination Of Sub Micron Bubbles And Particulate Matter

This paper reports on a newly developed sensor measuring the sound attenuation in situ at 10 MHz on a 10 cm short sound path, terminated by a metal reflector and a piezo quartz transducer on opposite sides. Different decreasing echoe burst amplitudes are very precisely measured for the calculation of the attenuation in the medium under test. At present stage of development the experimental sensor, which is to be used for particle and bubble spectrometry, turned out to allow for reasonable resolution of the attenuation of about 0.001 m , corresponding to roughly 2 ppm of typical particulate matter concentration, thus reaching e. g. the range of seston concentrations in many coastal waters.