Introduction to the special issue on ultrasonic transducers for high temperature applications

This Special Issue reflects a growing awareness within the ultrasonics community for improvement in high temperature ultrasonic devices. Its proponents range from the non-destructive evaluation (NDE) community, where the inspection of ´hot plant´ and installations has long been recognized, through to flow monitoring and characterization of chemical processes and reactions at elevated temperature. Within the transducer sector, the requirement for thermally stable transducers and materials capable of withstanding elevated intrinsic power levels over a broad range of ambient temperatures is becoming increasingly important. The Special Issue comprises seven papers covering a broad spectrum of topics. For convenience, we have tried to group the manuscripts into categories relating to materials, devices, and applications.