Field Emission Cooler Development

The on-going miniaturization of satellites requires concurrent development of miniaturized cooling/heat rejection devices. Cooling by field emission of electrons offers an attractive approach that until recently could not be considered. To test it, wehave conducted preliminary experiments and measured significant emitter cooling/temperture drop using an unoptimized carbon nanotube (CNT) field emission (FE) cathode originally constructed for low power electric propulsion applications. Approximateanalytical model was developed to explain the observed behavior. The model indicates that heat transport approaching a mW was accomplished and that a theoretical limit is of the order of 100 W/cm^2. Thus cooling by electron field emission is feasible andits development is herein proposed.In Phase I we will construct an improved FE device for the purpose of accurate calorimetric measurement of heat rejection from the emitter/cathode and heat gain on the anode. Emission experiments will be conducted in temperature range from 400 to 77 K todetermine the feasibility of cryogenic FE coolers. The experiments will be supported by concurrent modeling to develop performance prediction capability. A search for early FE cooler application will be conducted and the identified application will bethe focus of the Phase II device development.Cost effective, high efficiency, compact FE coolers would find application in many space and terrestrial devices in both military and commercial markets. These devices include IR sensors and imagers, cryogenic storage, magnetic resonance imaging andrefrigeration in medical applications, high density digital processors and power electronic components. The market is in the $M annually.