Thermal Ion Measurements for the KiNET-X Mission

Observations of the thermal properties of ionospheric ions can provide a more complete understanding of the underlying physics. Petite-Ion Probes (PIPs) are small retarding potential analyzers (RPAs) whose data consist of a series of measured anode current vs applied screen voltage (IV) curves over time. Scalar thermal ion properties of the measured plasma can be determined by forward modeling IV curves for a PIP on a (sub-)payload charged to a potential (Vs) in a drifting Maxwellian plasma, with ion temperature (Ti) and density (ni), to these measured PIP IV curves. However, the results of a fit to a single PIP’s data is highly sensitive to changes in the defined assumptions for the range and initial estimated values of the scalar parameters. As most investigations employ multiple collocated PIPs with different look directions, the uncertainty in the resulting scalar thermal ion parameters can be reduced by finding a plasma distribution that best fits multiple PIPs’ simultaneously collected IV curves. The Kinetic-scale energy & momentum transport experiment (KiNET-X) investigated kinetic-scale ionospheric plasma transport for a known input energy & momentum by measuring ionospheric perturbations near sounding rocket barium releases. The diagnostic payload, launched May 2021 from Wallops, carried four pairs of main-payload-mounted PIPs onboard. We will present visualizations of the phase space distributions of the thermal ions from the combined measurements from multiple onboard PIPs. Additionally, we will show how these can guide assumptions for the scalar fitting and results of our improved scalar fitting method.