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The identity and the energy distributions of positive and negative ions electrostatically extracted from the liquid phase in an ionic liquid ion source (ILIS) are analysed with a time-of-flight mass spectrometer and a multi-grid retarding potential analyzer. Accurate energy measurements using ionic liquids in an externally wetted configuration are reported for the first time. Droplet-free beams are produced using the ionic liquid 1-ethyl-3-methylimidazolium bis(triflouromethylsulfonyl)amide (EMI-Im) in which the solvated ions (EMI-Im) n EMI + and (EMI-Im) n Im − with n = 0, 1, 2 are observed. The small ion source size and the energy distribution widths and deficits of a few electronvolts are quite similar to those of liquid metal ion sources, confirming that ILIS can be used in applications requiring highly focusable beams, e.g. sub-micron ion lithography. Measurements also suggest that solvated ions with n 1 exhibit post-extraction fragmentation into lighter species at a rate increasing with their original degree of solvation. About 10% of the total beam current is carried away by metastable species that break up almost immediately after extraction while inside the emitter accelerating region.

We present the characterization of a miniaturized ionic liquid electrospray thruster for Nanosatellite applications. The thruster investigated features an emitter array of 480 emitter tips per square centimeter and a 1 cubic centimeter propellant tank with an entirely passive propellant supply, and is operated at a power level of < 0.15W. The paper presents energy-, and mass-resolving beam spectroscopy of the packaged thruster system, as well as two independent thrust measurements. This allows to derive thruster performance parameters under realistic firing conditions, including individual thruster e ciency contributions, specific impulse and thrust. Total thruster e ciencies of 36%, specific impulse of ⇠ 760s, including all losses, and thrust of 11 12.5µN are presented, at emission currents of 150µA, for a device of ⇠ 1cm 2. Current emission data without current decay of ⇠ 90h is presented, with a maximum of 172h.

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