Reliable and accurate temperature measurement during microwave processing of ceramic bodies is controversial. Although thermocouples are routinely used in conventional thermal furnaces, their presence in microwave furnaces can locally distort the electromagnetic field, conduct heat away from the sample, induce thermal instabilities and microwave breakdown, and lead to serious measurement errors. These thermocouple effects have been studied and found to be more pronounced in low-and medium-loss ceramic materials. To decrease the thermocouple effects during the processing of advanced ceramic materials, an optical, noncontact temperature sensing system has been developed, calibrated, and incorporated into a computer-controlled microwave furnace.

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technique is developed and the solution of the initial value problem, when to is comparable to T,, is obtained.The power reflection coefficient vs the rise time T, of an R2 [l] wave for various values of the electron gyrofrequency fb are calculated.

Microwave processing of metal oxide ceramic fibers offers several potential advantages. However, work so far has revealed