Development and application of advanced spectral analysis tools for Wind SWE

We present the initial results of a new multiple-beam analysis of the Wind spacecraft Solar Wind Experiment (SWE) thermal ion spectra. Wind SWE data products presently include plasma parameters based on fitting of an anisotropic core Maxwellian to each measured phase-space distribution function (PDF). This work is a first step towards expanding that analysis to describe more detailed, non-thermal PDFs. For periods of extremely non-thermal behavior, advanced spectral fitting has been undertaken to identify and characterize an arbitrary number of populations in the solar wind plasma PDF beyond the core Maxwellian. This analysis uses high time-resolution measurements of the magnetic field to guide identification and fit convergence, with particular emphasis on characterizing field-aligned proton beams. The non-thermal structure of the solar wind PDF bears the signatures of kinetic processes at work in the solar wind and in the corona. The present work focuses on the phenomenon of interpenetrating proton beams that have been associated with magnetic reconnection in the solar wind, and the kinetic structure of the reconnection exhaust plasma.