Studies of MEMS Colloid Thrusters

In this paper we have carried out numerical calculations and electrospray experiments to understand the underlying physics of colloid thruster operation and support the design of micro fabricated colloid thruster arrays. The calculations show that the Hagen-Poiseuille analytic solution predicts the steady flow behavior of the pressure feed system with reasonable accuracy. Our electrostatic simulations illustrate the importance of extraction electrode design to minimize the startup voltage, to minimize emitter-to-emitter interactions, to maximize thrust and to control dispersion in droplet velocities and therefore, the thrust vector. In addition, the experiments reveal that external wetting of the micro emitter electrode can prevent formation of the electrospray.