Nonlinear Plasma Signatures from Orbital Debris in Space

Orbital debris and meteoroids immersed in space plasma obtain an electric charge, enabling them to electromagnetically interact with the ambient environment.  The linear response of plasma in the presence of a charged surface is the well-known plasma sheath and wake.  Charged objects can also produce nonlinear responses in the form of coherent plasma structures (such as solitons, shocks, and vortices) that should be detectable in situ.  Understanding the physics of debris-generated nonlinear plasma signatures would enable us to use these signatures to sense, characterize, and track debris. 

The nature of a debris-generated soliton depends on the charge/size of the particle, environmental parameters, and the underlying wave mode.  Solitons can either propagate with the particle (pinned soliton) or propagate ahead of the particle motion (precursor soliton) and can have scale sizes ranging between the Debye length and ion skin depth.  The theory for soliton generation in an ideal setting is understood and has been experimentally confirmed using dusty plasmas.  However, the soliton physics in a realistic, inhomogeneous, 3D plasma is not well understood. 

In this presentation we will discuss theory and simulations relating to the production and propagation of solitons in a realistic space plasma environment.  The characteristics of the soliton (e.g., scale size, electrostatic/electromagnetic nature) change with the angle between the debris velocity and the background magnetic field.  A nonuniform ambient plasma affects the formation and propagation of solitons.   Understanding these details will inform the sensing of orbital debris.