Electrospray Propulsion

Abstract

Micro-propulsion has been studied for many years due to its applications in small-tomedium sized spacecraft for precise satellite attitude control. Electrospray thrusters are promising thrusters built upon the state of the art in micro-technology and with flexible performance in terms of their high efficiency and high specific impulse. One challenge is to investigate in detail the mechanism for ion emission to complement experimental results and understand better how emission occurs in the micro to nano scale. Thus, atomistic modeling is used to understand properties of emitted charged particles which determine how the thrusters perform.As a preliminary study of ion emission from Taylor cones, ion evaporation from 3 -5 nm droplets was observed in molecular dynamics (MD) simulations to validate the atomistic modeling and to investigate activation energies. Ion emission was examined in terms of internal and external electric fields and the activation energies of each case were obtained using Schottky's model and direct energy calculation to compare with experimental values. Ion emission was mainly observed with electric field strengths between 1.2 -2.0 V/nm and the emitted species include both solvated and non-solvated ions. Propulsive properties from Taylor cones are examined using results from the analysis of electric current from ion emission.In addition to an observation of ion emission from liquid droplets, numerical simulations for interactions between a solid plate and liquid droplets were conducted with MD simulation. It was concluded that another selection of force field needs to be considered to pursue further details, such as electrochemical effects.

Plasmas for space propulsion

“…Electrostatic acceleration of charged ions or droplets extracted from fine needles by kilovolt-biased electrodes are the basis of electrospray micro-propulsion [12]. Tens to thousands of individual emitters are arranged in arrays or slits for versatile operation and provide thrust in the range ∼1-10 3 µN.…”

“…Electrospray propulsion includes colloidal thrusters, field emission electric propulsion (FEEP) devices [13], and ionic liquid ion source (ILIS) devices. The two first concepts will be flight-tested in the coming LISA Pathfinder mission, while the last one, with some promising advantages [12], is still at the laboratory stage.…”

Characterization of an ionic liquid electrospray thruster with a porous ceramic emitter

“…The Electrospray thruster [1] can be used for space missions such as micro-nano satellite orbit maintenance or maneuvering, formation flight, and gravitational-wave detection. This thruster produces thrust by emitting ions and droplets from a charged surface (i.e.…”

Correction: Dielectric Materials with Deposited Electrode Layers for Electrospray Arrays

“…The liquid is then accelerated towards the apex, along with the ions and is released as a thin jet, or a stream of ions, or both. 18 This combination of effects was considered and the current transported in the cone-jet formation of an electrospray device, operating within the droplet regime, was experimentally verified by de la Mora 19 as…”