High Q ultrasonic liquid resonators with concave transducers

Abstract

Experience with cylindrical ultrasonic liquid resonators (volume 2–20 ml) in the 0.1–4 MHz range employing concave quartz transducers is reported. The static overpressure applied on the liquid cavity, which causes concave bending of the quartz, improves the Q factors of the liquid resonator (for a water-filled 15 ml cavity, up to Q∼1.1×105 near 0.4 MHz and for a 2 ml cavity up to Q∼3.4×104 near 1.8 MHz and also reduces absorption effects from gas inclusions. For illustration absorption measurements on aqueous 0.1 M MgSO4 are shown. Some analogies to characteristic properties of dielectric and optical resonators are drawn.