MIT's Tiny 3D Printed Thruster Uses Ions For Propulsion

Researchers at MIT have invented a small 3D printed thruster that emits a stream of pure ions. The thruster could be used as a low-cost and efficient propulsion source for miniature satellites in the future. The thruster is the first of its kind to be entirely manufactured using additive processes.

It was built using a combination of 3D printing and hydrothermal growth of zinc oxide nanowires. MIT also notes it's the first thruster of its type to produce pure ions from the ionic liquids used to generate propulsion. Pure ions make the thruster more efficient than similar devices and give it more thrust per unit flow of propellant.

The nanothruster is very small at about the size of a dime. The amount of thrust it provides is small and is measured on a scale of a few tenths of micronewtons. To put that in perspective, MIT says the thrust is equal to half the weight of s sesame seed on a hamburger bun.

While the total amount of thrust is minuscule, a CubeSat or other small satellite can use the small amount of thrust to accelerate or maneuver in the frictionless environment of orbit. The thruster operates electrodynamically, producing a fine spray of accelerated, charged particles emitted to produce a propulsive force.

The particles come from a type of liquid salt called ionic liquid. The MIT design has a 3D printed body with a reservoir of ionic liquid and a miniature forest of emitter cones coated with zinc oxide nanowires hydrothermally grown on the cone surfaces. When a voltage is applied between the emitters and a 3D printed extractor electrode, charged particles are ejected from the emitter tips.

The pure ion jet was detected using mass spectrometry. Typically an electrospray produced from ionic liquids contains ions and other species of ions mixed with neutral molecules. Researchers say that the pure ion jet was a surprise, and the team still isn't sure how it was produced.