Carbon NanotubeCopper Composite as Electron Emitter for Passive Spacecraft Discharging

This SBIR project will develop and demonstrate efficient electron emitter based on carbon nanotubecopper (CNT-Cu) composite for passive discharging of spacecraft in plasma environment. A spacecraft moving through harsh plasma environment collects electrons, which leads to the spacecraft charging up to several kilovolts. High voltage between different parts of the spacecraft can ignite arcing, which leads to mechanical damage of spacecraft surface, causes unexpected blackouts and even shutdowns. Today, this problem is solved either by spacecraft discharging by electron emission from auxiliary cathodes or special treatment of the spacecraft surface. In the latter, electric charge is deposited homogeneously to avoid potential build up between different parts of the spacecraft. The use of auxiliary cathodes requires additional power sources that increase the spacecraft mass. In Phase I, we will fabricate an electron emitter based on CNT-Cu composite and produce test samples of selected materials and measure their emissivity, sputtering and lifetime, which are expected to exceed that of emitters based on triple junctions. We will also model the electron emission from these materials in a plasma environment. Phase II will develop a prototype emitter from candidate material and demonstrate its superior properties under conditions typical for geostationary Earth orbits.