Electron emission from micro-architectured materials for plasma applications

Micro-engineered materials are predicted to have a small secondary electron emission (SEE) because their micro cavities should trap emitted electrons. Low SEE properties of these materials can be useful for various plasma applications including, Hall thrusters. It was previously demonstrated that the use of, for example, carbon velvet as the channel wall material for a Hall thruster can lead to dramatic improvements of insulating properties of magnetized thruster plasma allowing to reach significant dc electric fields of ~ 1kV/cm. Very recent measurements of SEE yield from a carbon velvet demonstrated a significantly smaller SEE yield from this engineered material as compared to graphite and much smaller than boron nitride ceramics. These results were obtained using a new experimental setup for SEE measurements at PPPL.