We outline the design, construction and testing of a field effect neutralizer, which provides a source of up to 6 mA of electron emission to maintain charge neutrality for the LISA Pathfinder mission spacecraft. The low mass, low power neutralizer uses silicon field emitter arrays and has been engineered for integration into the LISA Pathfinder micro-propulsion system. The silicon emitters are constructed using micro-fabrication techniques and electron beam lithography to ensure uniformity and precise control of emitter location. Control of the manufacture processes, plasma-enhanced vapour deposition, wet and dry plasma etch and various coatings, has been optimized to achieve robust reproducible devices suitable for space use.

Resonant field electron emission was observed from amorphous diamond thin film. An ultrathin, i.e. ∼2 nm, amorphous diamond thin film highly localize on a single sharp Si tip apex was used for the experiments. Tip specimens were fabricated by state-of-the-art microfabrication techniques, including high-resolution electron beam lithography, plasma dry etching and local amorphous diamond deposition on the tip apex. It was observed from current-field (I-E) characteristics that in the applied macro-field of typically 11-12 MV m −1 there are reversible and relatively strong current peaks, in contrast to the normal current instability phenomenon. The results confirm the effect of resonant tunnelling from amorphous diamond thin films.