FEA cathodes (FEACs) for space based applications

Summary form only given. In controlled high vacuum environments, field emitter array have shown substantial capability, but have failed in harsher environments more typical of space applications. We argue that a combination of localized arc suppression coupled with robust, low work function coatings such as zirconium, carbide can provide the needed raggedness to withstand energetic ions, oxygen fluxes, and adsorbates typical of a spacecraft environment. In this work, we present a survey of the requirements and capabilities of FEACs based on an analytical model of FEA performance; a summary of the model and its implementation shall be briefly discussed. From it we ascertain the relative advantages of FEACs as a function of materials, geometry, and space charge limitations, for EDTs, EP systems, and spacecraft charge control. We identify what is required of FEACs in terms of emission performance, lifetime, operational configurations and conditions (operation in a 1-10 microTorr pressure environment current densities of less than 0.1 Amps/cm/sup 2/, and gate voltages between 50-100 Volts). We discuss recent progress in modeling (device and space charge effects).