Detecting vibrations in liq. - by piezoelectric transducer partic. for low frequencies and high temp. e.g. in nuclear reactor coolant constituted by liq. metal

摘要

A detector of vibrations in a liq. comprises a piezoelectric transducer in a cavity sealed by a membrane in contact with the liq. A vacuum is maintained in the cavity. The membrane is connected to one of the faces of the transducer by a component which transmits vibrations, made of a material which is thermally insulating. The other face of the transducer is fixed and the cavity has a fluid-tight passage for an electric conductor. The detector is partic. adapted for detecting low-frequency vibrations transmitted by a liq. at high temps., e.g. the liq. metal coolant of a nuclear reactor. Satisfactory thermal insulation is achieved through the vacuum established in the cavity and the mechanical transmission component. Low frequency vibrations are detected because of the good electrical insulation and the amplification due to the membrane.