Contactless inductive bubble detection in a liquid metal column

The detection of bubbles in liquid metal is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The electrical conductivity of the liquid metal is relatively high, which can be exploited with contactless methods based on electromagnetic induction. We will present a measurement system which consists of one transmitting coil and a planar gradiometer on opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe.