Ultrasonic probes for high temperature immersion measurements

Ultrasonic probes for high temperature measurements in immersion are presented. These probes consist of piezoelectric transducers and buffer rods, and may be operated in the pulse echo mode. The probes can operate to temperatures as high as 215 °C without requiring a cooling system. For imaging purposes, one end of the clad buffer rod is machined into a semi-spherical concave shape, of which the purpose is to focus the ultrasound. The operating frequency is between 5 and 9 MHz. Ultrasonic images, produced using a mechanical raster scan with the probes fully immersed in silicone oil at elevated temperatures, are presented. The importance of the signal-to-noise ratio in the pulse-echo measurement is discussed.