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Abstract Shocks in collisionless astrophysical plasmas redistribute some of the incident flow energy into both thermal and non‐thermal energy. Quantifying the partition of that energy amongst various particle species or their sub‐populations, and electromagnetic energy, represents a fundamental goal of shock physics. It embodies the role of the equation of state for the system. Here we apply a framework to assess all the incident and downstream energy fluxes at a crossing of Earth's bow shock for which the upstream magnetic field was roughly aligned with the shock normal direction. Such quasi‐parallel shocks are known to be non‐steady and to produce significant populations of suprathermal particles. We quantify the evolution of all the important carriers of energy flux through the shock region. We sub‐divide the proton population into thermal, suprathermal, and energetic components in order to investigate the shock's efficiency in energizing the nonthermal particles. While the largest energy fluxes are found in the incident proton ram energy and downstream proton thermal enthalpy fluxes, a significant suprathermal population pervades the regions both up‐ and downstream. We also evaluate the energy fluxes attributable to fluctuations in the fluid and field parameters. 

Abstract The overarching science goal of the Tandem Reconnection And Cusp Electrodynamics Reconnaissance Satellites (TRACERS) mission is to connect the cusp to the magnetosphere by discovering how spatial or temporal variations in magnetic reconnection drive cusp dynamics. This goal will be achieved with a simple mission design comprising two identical small spacecraft in identical low-Earth orbits in a follow-the-leader configuration. TRACERS will make repeated measurements in the cusp for a twelve-month primary mission using plasma and field instruments. These data will be analyzed using established dual-spacecraft techniques and supported by modeling that ensures science closure on the objectives. The TRACERS team leverages hardware collaborations from the University of Iowa, Southwest Research Institute, University of California Los Angeles, University of California Berkeley, and Millennium Space Systems. The larger science team consists of experts in reconnection, cusp physics, and modeling. TRACERS is dedicated to its proposer, and original Principal Investigator, Professor Craig Kletzing. 

The observation and interpretation of electric fields have been crucial to the understanding of space physics, particularly on the kinetic scale. The basic principle for electric field measurements can be considered straightforward. However, it has proven difficult to measure electric fields from current state-of-the-art voltage probes without perturbing the space plasma itself. There are numerous documented observations from electric field instruments that have no geophysical explanation for their behavior, implying that they can only be induced by the interaction between probe and plasma. The cause of these anomalies requires a full understanding of the factors that contribute to the measurements of voltage probes. We developed a procedure to isolate the sources of impedance between various components of a physical voltage probe model and a controlled plasma population via the space physics simulation chamber at the Naval Research Laboratory. This paper describes the laboratory setup, procedure, and results from the first round of tests performed on this voltage probe model and discusses improvements to future campaigns. Initial results show that some changes to the model design and the measurement of plasma parameters are required, but interactions with the plasma are observed, and the calibration method used successfully returns impedance values similar to values from direct measurements. 

Context. Parker Solar Probe (PSP) performs Venus gravity assists (VGAs) in order to lower its perihelion. PSP takes high-cadence electric and magnetic field observations during these VGAs, providing the opportunity to study plasma waves in Venus’s induced magnetosphere. Aims. We summarize the plasma environment during these VGAs, including the regions of near-Venus space that PSP traversed and the key boundary crossings. We comprehensively identify Langmuir, ion acoustic, whistler-mode, and ion cyclotron waves during these VGAs and map the location of these waves throughout near-Venus space. Methods. This study analyzes different data products from the PSP FIELDS instrument suite from throughout the first five VGAs. Results. We compare the FIELDS instrumentation capabilities to the capabilities of the plasma wave instruments on board the Pioneer Venus Orbiter (PVO) and the Venus Express (VEX). We find that the PVO electric field instrument was well suited to observe Langmuir waves, especially near the bow shock and in the foreshock. However, evaluation of the other plasma waves detected by PSP FIELDS reveals that PVO and VEX would have often been unable to observe key features of these waves modes, including maximum power, bandwidth, and propagation direction. These wave characteristics provide critical information on the wave generation mechanisms and wave-particle interactions, so provide fundamental information on the nature of Venus’s induced magnetosphere. Conclusions. These results highlight the advances in plasma wave instrumentation capabilities that have been made in the decades since the PVO and VEX eras, and illustrate the value of a plasma wave instrument on a new Venus mission. 

The current state of the art thermal particle measurements in the solar wind are insufficient to address many long standing, fundamental physical processes. The solar wind is a weakly collisional ionized gas experiencing collective effects due to long-range electromagnetic forces. Unlike a collisionally mediated fluid like Earth’s atmosphere, the solar wind is not in thermodynamic or thermal equilibrium. For that reason, the solar wind exhibits multiple particle populations for each particle species. We can mostly resolve the three major electron populations (e.g., core, halo, strahl, and superhalo) in the solar wind. For the ions, we can sometimes separate the proton core from a secondary proton beam and heavier ion species like alpha-particles. However, as the solar wind becomes cold or hot, our ability to separate these becomes more difficult. Instrumental limitations have prevented us from properly resolving features within each ion population. This destroys our ability to properly examine energy budgets across transient, discontinuous phenomena (e.g., shock waves) and the evolution of the velocity distribution functions. Herein we illustrate both the limitations of current instrumentation and why higher resolutions are necessary to properly address the fundamental kinetic physics of the solar wind. This is accomplished by directly comparing to some current solar wind observations with calculations of velocity moments to illustrate the inaccuracy and incompleteness of poor resolution data.