  A multi-anode electrode geometry suitable for vacuum breakdown is proposed in
this paper. This electrode geometry forms a unique electric field distribution
based on its anode configuration which is different from the conventional
electrode geometry. There exists a region A between the insulated-anode and the
remote-anode where the electric field vector has opposite directions. The
existence of region A directly affects the movement of electrons in the initial
stage of the discharge, thereby changing the process of vacuum breakdown. The
variation of discharge process affects the generation and propagation mechanism
of plasma, forming a plasma plume in favor of the propulsion performance of
thrusters. The photograph of plasma plume and the electron density spatial
distribution of plasma plume preliminarily prove the pinch effect of
multi-anode electrode geometry on the radial diffusion of plasma. In the
optimization of remote-anode of multi-anode electrode geometry, the variation
of the distance of cathode and remote-anode (short for D) is found to affect
the pinch effect. Through the reduction of D, the directional jet effect of the
multi-anode electrode geometry is enhanced under the same discharge parameters.
Applying it to the VAT (multi-anode VAT) and comparing it with the VAT based on
conventional electrode geometry (conventional VAT), it is found that the
propulsion performance of multi-anode VAT is superior to conventional VAT, and
it is further promoted with the decrease of D. Under the same discharge
parameters, the impulse bit and the thrust-to-power ratio of the multi-anode
VAT is able to be increased by a factor of 26 and 2.88 respectively compared
with the conventional VAT. Theoretical analysis and investigation of propulsion
performance validate the potential application advantages of the multi-anode
VAT in the field of nanosatellite propulsion.
