TOF curves of formates using a stainless steel needle ( i.d.). The highest current corresponds to the highest voltage and pressure on the liquid reservoir. (a) ; ; ; . (b) ; ; varying and . (c) ; ; ; ; over , the regimes are ionic. (d) in positive and negative modes; ; .
Representative propulsion characteristics of the formate-based ionic liquids, with units indicated on each curve. (a) For , note that high current losses take place in the extractor. (b) runs in the drop-dominated regime with low specific impulse and fair propulsion efficiency.
TOF spectra for electrosprays of pure . The left figure is a detail at shorter times, showing the steps associated to the ions. The figure to the right includes the full spectrum showing a large tail of charged drops. ; ; i.d.
Emissions from critical mixture of , below which the purely ionic regime (right) is sometimes observed. The mixed regime may also arise (left; , , ). Although the purely ionic regime arises at higher voltages, it remains “put” as the voltage is later reduced (right; , , ).
TOF spectrum for an electrospray of pure EMI–TfO showing almost purely ionic emission. ; .
TOF spectrum of seeded with acid showing a behavior close to the purely ionic regime.
TOF spectra comparing the emissions from with those of four other ionic liquids of relatively high surface tension and electrical conductivity.
Ionic liquids studied Refs. 18 and 19 including key physical parameters and the temperature at which their Taylor cones achieve the purely ionic regime. Cations: EMI=1-ethyl-3-methylimidazolium; DMPI=1,2-dimethyl-3-propylimidazolium; MI=1-butyl-3-methylimidazolium; MI=1-pentyl-3-methylimida-zolium; , commercialyzed by Cytec under the name Cyphos. Anions: .
Some characteristics of the ionic liquids synthesized by Garoz (Ref. 20). Anions: .
Propulsive characteristics of several formate propellants.
Characteristics of mixtures of as a function of concentration. regime; ionic regime; M&I means that both regimes are attainable at high and low voltages, respectively.
Electrical conductivities of several ionic liquids seeded with .
Physical properties of the ionic liquids used in Fig. 7. Cations: -ethyl-2-methylpyrazolium.
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