Infrared measurement of the temperature distribution of a repetitively pulsed electron beam extraction foil as a beam uniformity diagnostic

A presentation is made of experiments to measure the current extracted through the foil of an electron beam diode by observing the heating of the foil. Generally anode current density is measured with a dosimeter film, often of dubious linearity, or with Faraday cups which give a current density versus time map at isolated points or with an array of calorimeters. For the present measurements a fast scanning infrared camera is used to measure the temperature rise of the foil after a pulse. The measurement takes 600/mu/s for a single line scan or 16 ms for a full raster scan. 5 refs