Alternative Fabrication Techniques for and Emitter Densification of iEPs

At 10e9 V/m, ionic liquid ion source (ILIS) thrusters extract ions from ionic liquids -- room temperature molten salts—that are passively supplied. Fields of this order are achieved at the tips of Taylor cones—electrostatically stressed menisci that result from the balance of electric stress and surface tension on the liquid propellant -- which form on the ends of sharp structures, known as emitters. ILIS electrospray thrusters operate at modest potentials around 1.5 kV, require less than 0.65 W of operating power, and can produce microNewtons of thrust and a specific impulse of 2000-3000 seconds

This work aims to address the following challenges:
(*) Substrate selection and propellant transport – A substrate that lends itself to mature fabrication techniques and can support a passive propellant supply system (eg. wettable, porous) is desired.

(2) Electrochemistry – Emitters can be plated with or fabricated from inert materials to provide a benign electrochemical environment for improved thruster lifetime.

(3) Beam divergence – Ion emission can occur from Taylor cones forming at locations other than the emitter tip. Fabrication methods that allow better control over pore size can concentrate emission sites and decrease beam divergence.

(4) Densification – Techniques for fabricating emitters on the order of single µm’s can help realize thrust densities up to four orders of magnitude greater than the current state of the art.