Understanding the interaction of the near-Earth space environment with orbiting bodies is critical, both from a design and scientific perspective. In Low Earth Orbit (LEO), the interaction between the ionosphere and orbiting objects is well studied from a charging perspective. Not well understood is the effect of the ionosphere on the motion of LEO objects i.e. charged aerodynamics. This paper presents the implementation, validation, and verification of the hybrid electrostatic Particle-in-Cell (PIC) -Direct Simulation Monte Carlo (DSMC) code, pdFOAM, to study both the neutral and charged particle aerodynamics of LEO objects. The 2D aerodynamic interaction of a cylinder with a fixed uniform surface potential of −50 V and mesothermal O + and H + plasmas representative of ionospheric conditions is investigated. New insights into the role of bounded ion jets and their effect on surface forces are presented. O + bounded ion jets are observed to cause a 4.4% increase ion direct Charged Particle Drag (dCPD), while H + ion jets produce a net reduction in H + drag by 23.7% i.e. they cause a thrust force. As a result, we conclude that past work, primarily based on Orbital Motion Limited theory, does not adequately capture the physics of LEO charged aerodynamics. Hence, we recommend a revisit of conclusions regarding the significance of CPD to LEO objects -pdFOAM being an appropriate tool for this purpose.

This paper derives the generalised set of dimensionless parameters that scale the interaction of an unmagnetised multi-species plasma with an arbitrarily charged object - the application in this work being to the interaction of the ionosphere with Low Earth Orbiting (LEO) objects. We find that a plasma with K ion species can be described by 1+4K independent dimensionless parameters. These parameters govern the deflection and coupling of ion species k, the relative electrical shielding of the body, electron energy, and scaling of temporal effects. The general shielding length λϕ is introduced, which reduces to the Debye length in the high-temperature (weakly coupled) limit. The ability of the scaling parameters to predict the self-similar transformations of single and multi-species plasma interactions is demonstrated numerically using pdFOAM, an electrostatic Particle-in-Cell—Direct Simulation Monte Carlo code. The presented scaling relationships represent a significant generalisation of past work, linking low and high voltage plasma phenomena. Further, the presented parameters capture the scaling of multi-species plasmas with multiply charged ions, demonstrating previously unreported scaling relationship transformations. The implications of this work are not limited to LEO plasma-body interactions but apply to processes governed by the Vlasov-Maxwell equations and represent a framework upon which to incorporate the scaling of additional phenomena, e.g., magnetism and charging.

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