THE MEASUREMENT OF METAL TEMPERATURE BY AN ELECTROMAGNETIC INDUCTION METHOD

摘要

The basic principles of inductive thermometry are outlined and their relationship to the principles of electromagnetic methods of nondestructive testing are described. Measured values of the impedance of long and short solenoids with conducting cores are shown and compared with calculated values for the infinitely long solenoid. It is shown that the impedance loci for varying core conductivity for the short solenoid differs from that of the calculated loci for the infinitely long coil in that the ratio of maximum resis¬tance change to maximum reactance change decreases as the solenoid shortened. Measured impedance loci are also shown for a large flat coil and a small flat inductive thermometer sensing coil when placed adjacent to the surfaces of common materials. The impedance loci are shown and analyzed in a manner to aid in illustrating the principles of inductive ther¬mometry and to serve as aids in the future design of sensing coils and inductive thermometer circuitry.