The Sound Field of a Straubel X‐Cut Crystal

The sound beam generated in a liquid by a 7.5 megacycle Straubel X‐cut quartz crystal has been investigated by the phenomenon of streaming. The streaming patterns in carbon tetrachloride have been determined by measuring the velocities of sugar particles which have very nearly the same density as the liquid. The velocity distributions produced by a cylindrical sound beam in liquid contained a concentric cylindrical tank are found to be in good agreement with those predicted by Eckart's solution of the hydro‐dynamical flow equations. Comparison measurements with square X‐cut quartz crystals of the same frequency give poor agreement with theory. Since Eckart's analysis assumes uniform sound intensity across the beam, these experiments indicate that the sound beam radiated by a Straubel cut crystal is very uniform.