Thermal management: Effect of heater geometry on a dispenser cathode temperature

It is well known that heater geometry makes a difference in heat transfer between the heater wire and the cathode surface. However, empirical data is not available throughout the industry. A series of tests have been performed to evaluate the effect of different heater coil configurations on cathode temperature, as well as the effect of wire diameter. This paper will present results of this research and results will be compared with theoretical results based on a conduction heat transfer theory in order to find a reliable way to include this theory in the design process. Only results of tests with 0.250" diameter samples are presented in this paper. Test on samples with different heater bucket diameters are currently evaluated and results will be presented elsewhere.