Improved Fluid Modeling of Space Debris Generated Ion-Acoustic Precursor Solitons

TL;DR

This work addresses whether dynamic charging and impermeable debris surfaces affect ion-acoustic precursor soliton excitation by supersonic debris in a plasma. It combines a self-consistent 1D fluid-Poisson model with a time-dependent debris charge $Q(t)$ and a 2D impermeable-surface framework to test realism against earlier Gaussian-source theories. The key findings are that charging dynamics do not hinder precursor soliton formation, and that a finite impermeable object that allows plasma flow around it restores upstream–downstream connectivity and enables precursor solitons, aligning with previous simulations and experiments. These results reinforce the use of precursor solitons as observable signatures for debris tracking in space plasmas and clarify boundary-condition effects relevant to modeling efforts.

Abstract

This study reexamines the excitation of ion-acoustic precursor solitons by a supersonically moving charged debris object, incorporating two previously overlooked physical factors: the dynamic charging of the debris and the impermeable nature of its surface. The influence of charging dynamics is explored using an enhanced one-dimensional fluid-Poisson model, where the source charge is treated as a dynamical variable and solved self-consistently alongside the core plasma equations. By comparing these results with prior fixed-charge models, we evaluate the effects on soliton onset and propagation, finding that charging dynamics does not hinder soliton generation or evolution. To assess the impact of the impermeability of debris surface, a two-dimensional fluid model simulates the interaction between an electrostatically biased, impenetrable object and a flowing plasma. Modeling the object as an infinite wall disconnects the upstream and downstream plasma regions, forming a sheath without solitons -- consistent with earlier fluid and particle-in-cell simulations. However, replacing the wall with a finite object enables plasma flow around it, restoring upstream-downstream connectivity and naturally generating precursor solitons.

Figures (10)

• Figure 1: Development of floating potential on a stationary source with $\sigma = 0.1$. The inset shows the early evolution of the surface potential on the charged debris source.
• Figure 2: The $\omega-k$ dispersion relation obtained from the fluctuations in space-time during early times $t = 1.0 - 98$ before precursors and wakes start to form.
• Figure 3: Temporal evolution of the floating potential on a moving source with $\sigma = 0.1$. The inset shows a zoomed view of the early time dynamics of the surface potential of the debris.
• Figure 4: Spatio-temporal evolution of density using \ref{['NCE_eqn1']}-\ref{['NPE_eqn3']}, and \ref{['NCHGVd_eqn4']} showing precursors and wakes with dynamic charging of the moving source. Here $v_{d} = 1.15$, $x_0 = 10$, $w = 0.50$ and $\sigma=0$.
• Figure 5: Spatio-temporal evolution of density using \ref{['NCE_eqn1']}-\ref{['NDYN_source']} showing precursors and wakes from a moving source with fixed charge. Here $v_{d} = 1.15$, $\phi_{d0} = 2.96$, $x_0 = 10$, $w = 0.50$ and $\sigma=0$.