Non-Maxwellian velocity distribution functions for Coulombic systems out of equilibrium.

The velocity distribution function (VDF) of ions in the solar wind, as observed by spacecraft at 1 AU and elsewhere in the heliosphere, exhibits a consistent trend: at low energies in the solar wind frame, the distribution is largely Maxwellian-the core; at higher but still modest energies in the solar wind frame, the distribution follows a power law ( ∝ , where is the VDF, is the speed in the solar wind frame, and is an arbitrary spectral index parameter)-the tail-with a spectral index of ≈ 5 being extremely common. Several theories have been proposed to explain this common index. Among these theories is that the tail is a natural consequence of an ensemble of particles obeying Coulomb's law (Randol & Christian 2014, 2016).

Response in electrostatic analyzers due to backscattered electrons: case study analysis with the Juno Jovian Auroral Distribution Experiment-Electron instrument.

In this study, we introduce a model to characterize electron scattering in an electrostatic analyzer. We show that electrons between 0.5 and 30 keV scatter from internal surfaces to produce a response up to ~20% of the ideal, unscattered response.

Reflections of ions in electrostatic analyzers: a case study with New Horizons/Solar Wind Around Pluto.

Electrostatic analyzers (ESAs), in various forms, are used to measure plasma in a range of applications. In this article, we describe how ions reflect from the interior surfaces of an ESA, the detection of which constitutes a fundamentally nonideal response of ESAs. We demonstrate this effect by comparing laboratory data from a real ESA-based space instrument, the Solar Wind Around Pluto (SWAP) instrument, aboard the NASA New Horizons spacecraft, to results from a model based on quantum mechanical simulations of particles reflected from the instrument's surfaces combined with simulations of particle trajectories through the instrument's applied electrostatic fields.

The entrance system laboratory prototype for an advanced mass and ionic charge composition experiment.

Electrostatic analyzers (ESA) have been used extensively for the characterization of plasmas in a variety of space environments. They vary in shape, geometry, and size and are adapted to the specific particle population to be measured and the configuration of the spacecraft. Their main function is to select the energy per charge of the particles within a passband.

Structures and spectral variations of the outer heliosphere in IBEX energetic neutral atom maps.

The Interstellar Boundary Explorer (IBEX) has obtained all-sky images of energetic neutral atoms emitted from the heliosheath, located between the solar wind termination shock and the local interstellar medium (LISM). These flux maps reveal distinct nonthermal (0.2 to 6 kilo-electron volts) heliosheath proton populations with spectral signatures ordered predominantly by ecliptic latitude.