Traditionally, thermionic electron emission from a filament is used to generate the electrons. Power is a premium resource on scientific space vehicles, and researchers strive to reduce power consumption as much as possible. Field emission cathodes provide an alternative approach at generating electrons without the heating power needed in a filament-based design.
Field emission is used to extract the electrons without heating the cathodes.
However, an issue that needs investigation is their lifetime. Emission depends upon tip radius and work function, which may change during operation and degrade the device characteristics. Sputtering of the tip by residual gas molecules ionized by the emitted electrons blunts the emission point and increases the required voltage. The sputtering is highly dependent on the gas environment. No report could be found in the literature concerning nitrogen, the most abundant gas in the Earth's atmosphere and the second most abundant gas on Mars's atmosphere.