(109d) Dielectric Property Measurement Over a Wide Range of Temperatures

Determining dielectric properties can present unique challenges, some within the material, and some inherent in the measurement equipment. A newly designed high temperature probe addresses both of these issues and allows the user to take dielectric property measurements up to nearly 1000 ºC.

If a material is not completely uniform, using a standard probe and network analyzer, repeated measurements will give a range of values due to fringing effects and the non-homogeneity of the sample. Accurate values thus require averaging of many measurements. Further, dielectric properties are a function of temperature, with the practical result that thermal runaway or thermal plateau can result during microwave heating processes.

The new probe developed by Y-12 addresses these problems; it gives accurate repeatable dielectric measurements up to 1000 ºC, an improvement of nearly 800 ºC over other property measurement probes. This data allows for effective modeling of high temperature microwave processing.