Surface Morphology and Lifetime Assessment of Re- generable Field-Emission Cathodes at Elevated Background Pressure

摘要: The research reported here focuses on the surface topography of a fieldemission cathode for use in Electric Propulsion (EP) that has potential very long lifetime and added ability to be re-generated when emitter sites become damaged. was formed by application an ion-extracting electric applied heated indium-coated tungsten needle. For reasons not understood at this time, electrostatic field caused modification indium-oxide layer such large number nano-sharp crystal protrusions were created solid In2O3. When modified needle then subjected electron-extracting potentials stable long-lived electron emission observed. Electron from observed over 1,700 hours – attributed presence multiple allowed naturally jump next-best site after single tip became blunted. Also is comparison between In2O3 tips with single-needle tips. Long duration experiments performed, as well studies showing current each type background pressure increased 10 -8 Torr up -4 Torr. Longer life demonstrated every experiment compared emitters. lasted 50 longer than bare vacuum pressures -5 range.