Radiation-induced solidification of ionic liquid under extreme electric field

Abstract

An extreme electric field on the order of 10(10) V m(-1) was applied to the free surface of an ionic liquid to cause electric-field-induced evaporation of molecular ions from the liquid. The point of ion emission was observed in situ using a TEM. The resulting electrospray emission process was observed to create nanoscale high-aspect-ratio dendritic features that were aligned with the direction of the electric field. Upon removal of the stressing field the features were seen to remain, indicating that the ionic liquid residue was solidified or gelled. Similar electrospray experiments performed in a field-emission scanning electron microscope revealed that the features are created when the high-energy electron beam damages the molecular structure of the ionic liquid. While the electric field does not play a direct role in the fluid modification, the electric stress was critical in detecting the liquid property change. It is only because the electric stress mechanically elongated the fluid during the electrospray process and these obviously non-liquid structures persisted when the field was removed that the damage was evident. This evidence of ionic liquid radiation damage may have significant bearing on electrospray devices where it is possible to produce high-energy secondary electrons through surface impacts of emitted ions downstream of the emitter. Any such impacts that are in close proximity could see reflected secondary electrons impact the emitter causing gelling of the ionic liquid.

Relationship between Viscosity and Resistance of Oil Film: A New Way to Investigate the Controllable Friction between Charged Interfaces Lubricated by Ionic Lubricating Oil

“…The electrorheological effect states that when an electric field is applied to some solutions, the liquid can quickly convert from a Newtonian fluid to a solid‐like viscoelastic body with a very high yield stress in a very short period of time (about 10 −3 s) and then quickly return to a state of very low viscosity after the removal of the electric field. [ 52,53 ] In this study, electricity, which acted as a stimulus source, stimulated ions in the lubricating oil to gather them, which made the viscosity of the lubricating layer increase instantaneously and the coefficient of friction change abruptly. The number of excited ions in the ionic liquid‐lube oil solution could be controlled by changing the current intensity, so that the amplitude of the abrupt change in the coefficient of friction could be adjusted.…”

Lifetime Considerations for Electrospray Thrusters

“…In addition to propellant accumulation from overspray, other considerations can contribute to reduced lifetime. Flux of electrons towards the emitter due to the positive potential of the emitter, known as electron backstreaming (EBS), can induce electrochemical reactions in the propellant that can result in emitter damage and propellant decomposition near the emission site [16]. Chemical reactions due to the electric double layer can also contribute to propellant decomposition [17,18], leading to growth of undesirable byproducts on, or near, the emission surface.…”

The emission properties, structure and stability of ionic liquid menisci undergoing electrically assisted ion evaporation

“…to capture the shape of the interface profile, the nature of fluid interactions with the tip and the characteristics of internal creeping flow while confirming that the source is operating in the pure ionic mode, for example, through simultaneous mass spectrometry of the beam. Electron microscopy has been attempted to observe the small menisci (Terhune et al 2016), however, the electron beam interacts strongly with the charged surface making these observations uncertain at best. The lack of empirical evidence emphasizes the relevance of studying these liquid structures through numerical simulations.…”