Analysis of Transient Heating of Phosphor Coatings

Abstract

This work examines how faithfully a layer of thermographic phosphor responds to a rapidly changing temperature of the substrate to which it is attached. A simple model is presented and applied to the specific situation of a ramp heating pulse of 200 C in 15 ms. The model predicts a time lag in temperature of about 6 ms for a 100 micron layer for a phosphor of thermal conductivity equivalent to glass. A 20 micron layer exhibits a 1/3 ms time lag. Experimental data for a rapidly heated nichrome wire provides supporting evidence that thin phosphor layers can follow such temperature changes on this time scale.