Detailed modeling and analysis of spacecraft plume/ionosphere interactions in low Earth orbit

Abstract

Detailed direct simulation Monte Carlo/particle-in-cell simulations involving the interaction of spacecraft thruster plumes with the rarefied ambient ionosphere are presented for steady thruster firings in low Earth orbit (LEO). A nominal mass flow rate is used to prescribe the rocket exit conditions of a neutral propellant species for use in the simulations. The charge exchange interactions of the steady plume with the rarefied ionosphere are modeled using a direct simulation Monte Carlo/particle-in-cell methodology, allowing for a detailed assessment of nonequilibrium collisional and plasma-related phenomena relevant for these conditions. Results are presented for both ram-and wake-flow configurations, in which the thrusters are firing into (ram) or in the direction of (wake) the free stream ionosphere flow in LEO. The influence of the Earth's magnetic field on the development of the ion plume is also examined for three different field strengths: two limiting cases in which B → 0 and B → ∞, and the LEO case in which B = 0.5 Gs. The magnetic field is found to have a substantial impact on the resulting neutral and ion plumes, and the gyroscopic motion of the magnetized ions results in a broadening of the ion energy distribution functions. The magnetic field model also incorporates a cross-field diffusion mechanism which is shown to increase the current density sampled far from the thruster.

Analysis and observation of spacecraft plume/ionosphere interactions during maneuvers of the space shuttle

“…The flow conditions and physical models used to simulate the plume interaction with the ambient flow are described below. Details of the MPIC computational framework and physical models that are used in these simulations are outlined in Stephani and Boyd [2014].…”

“…MEX collisions for Pr − O, O − O and Pr − Pr are modeled using variable hard sphere [Bird, 1994] Table 4. Additional details regarding the collision models used in these simulations may be found in Stephani and Boyd [2014].…”

“…In consideration of the gyroscopic parameters in equations (1) and (2), the O + ions are modeled as magnetized on field lines of infinite strength, B → ∞. An investigation of the impact of the magnetic field strength on the development of both the spacecraft neutral and ion plumes is presented in Stephani and Boyd [2014].…”

“…During the NH2 maneuver, the ISS was located 5 km upstream (+x direction) and 1 km below (+z direction) the Space Shuttle. To create a negative change in velocity, Endeavour's RCS jets were firing upstream in the +x direction directly into the ambient ionosphere flow, a condition which will be referred to hereafter as a ram flow configuration [Stephani and Boyd, 2014]. Also in this frame of reference, the Earth's geomagnetic field lines were aligned with the z axis, orthogonal to the shuttle velocity vector, and had a velocity equivalent to the orbital velocity relative to the shuttle.…”

Spacecraft plume interactions with the magnetosphere plasma environment in geostationary Earth orbit

“…Incorporating these effects is critical for capturing the development of the spacecraft plume in the plasma environment, particularly over large distances. Recent efforts [ Stephani and Boyd , ; Stephani et al , ] investigating spacecraft plumes in low Earth orbit (LEO) have demonstrated that interaction of the spacecraft neutral plume with the ambient plasma forms a relatively high‐density spacecraft ion plume. The propagation of this ion plume is determined primarily by the interaction with the magnetic field, but the development of the neutral spacecraft plume is also affected (albeit indirectly) by the magnetic field interaction owing to secondary charge‐exchange reactions.…”