Geometric Effects on Taylor Cone Formation for Porous Ionic Liquid Ion Sources

Ionic liquid ion sources (ILISs) are used in electrospray thrusters, offering high specific impulse but limited lifetimes.¹ A factor for poor lifetimes is plume interaction with the extractor, driven in part by off-axis emission, leading to short circuiting.¹ Additional emission sites are found to onset with increased voltage, but prediction of this is difficult. ^2,3

Robust numerical simulations exist in literature, but require experimental verification and do not elucidate Taylor cone location – a factor for axial emission.⁴ Literature predictions suggest Taylor cones sizes lay within the capabilities of optical visualisation ^2–4. Using optical visualisation, Taylor cone shape and size will be studied to allow better informed ILIS design for plume axiality. Taylor cones images on ILISs will be presented, identifying how their size and location vary.

1. Uchizono, N. M. et al. The role of secondary species emission in vacuum facility effects for electrospray thrusters. J Appl Phys 130, (2021).

2. Whittaker, C. B. & Jorns, B. A. Modeling multi-site emission in porous electrosprays resulting from variable electric field and meniscus size. J Appl Phys 134, (2023).

3. Perez-Martinez, C. S. Engineering Ionic Liquid Ion Sources for Ion Beam Applications. Aeronautics and Astronautics (Massachusetts Institute of Technology, 2016).

4. Gallud, X. & Lozano, P. C. The emission properties, structure and stability of ionic liquid menisci undergoing electrically assisted ion evaporation. J. Fluid Mech 933, 43 (2022).