Remote Measurement of Temperature in the Presence of a Strong Magnetic Field

Abstract

Pulse power systems generate heat in the presence of a large time varying magnetic field. In order to quantify the local heat generation, these systems need temperature sensing equipment. The magnetic field can induce signals in temperature sensors with electrical connections such as thermocouples and thermistors. Also, the power systems are often at a high electric potential when energized requiring robust electrical isolation schemes to prevent the system from discharging through the sensing equipment. As such, a sensing system has been developed that can remotely capture information to determine the temperature of a surface. This sensor is based on an interferometer using a thin sapphire die coated with nickel oxide as the sensing element. A model was developed to predict the behavior of the sensor in order to determine the ideal layer thickness. With this system temperature measurement has been demonstrated at a sampling rate of 30 Hz over a range of 20degC to 300degC with 20% precision. Because the technique explored in this research does not require physical connections to the sensor, the dilemma of the magnetic field and electrical isolation are bypassed.