A device for measurements of the temperature response to single discharges with high local resolution and fast response time

We report on a thermal device consisting of 14 thin film Au-Pd thermocouples designed to measure the transient temperature response of a sample (a thin 50 μm thick steel foil) submitted to a single discharge. Junctions as small as 4 μm2 were patterned using standard photolithography. The distance between the junctions (i.e. the local resolution of the device) is 20 μm. Using standard electron discharge machining (EDM) equipment, the temperature response due to a single discharge was measured. The maximum measured temperature was 280 °C for a thermocouple located on the backside of the steel foil at 61 μm from the center of the discharge. Large temperature gradients of 2.5 × 106 °C/m and quench rates of 5 × 105 °C/s have been measured. Analysis of the thermovoltage noise pattern allowed precise determination of the beginning and duration of the discharge. Preliminary results of the numerical calculations are given.