Characteristics of liquid film on the tip surface of indium field-emission electric propulsion thrusters

The characteristics of the propellant film on the tip surface of the field-emission electric propulsion thruster have a close relationship with the work state of the thruster. In this paper, the distributions of both the liquid film thickness and the fluid velocity along the needle tip have been calculated by building the liquid mechanics equations and a cone coordinate system suitable for the tip. The results show that the film thickness is tens to hundreds of nanometers and the fluid velocity along the needle tip is from tens of µm/s to a few mm/s.