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- Title
The Impact of Non‐Equilibrium Plasma Distributions on Solar Wind Measurements by Vigil's Plasma Analyser.
- Authors
Zhang, H.; Verscharen, D.; Nicolaou, G.
- Abstract
In order to protect society from space weather impacts, we must monitor space weather and obtain early warnings for extreme events if possible. For this purpose, the European Space Agency is currently preparing to launch the Vigil mission toward the end of this decade as a space‐weather monitor at the fifth Lagrange point of the Sun–Earth system. Vigil will carry, amongst other instruments, the Plasma Analyser (PLA) to provide quasi‐continuous measurements of solar wind ions. We model the performance of the PLA instrument, considering typical solar wind plasma conditions, to compare the expected observations of PLA with the assumed input conditions of the solar wind. We evaluate the instrument performance under realistic, non‐equilibrium plasma conditions, accounting for temperature anisotropies, proton beams, and the contributions from α‐particles. We examine the accuracy of the instrument's performance over a range of input solar wind moments. We identify sources of potential errors due to non‐equilibrium plasma conditions and link these to instrument characteristics such as its angular and energy resolution and its field of view. We demonstrate the limitations of the instrument and potential improvements such as applying ground‐based fitting techniques to obtain more accurate measurements of the solar wind even under non‐equilibrium plasma conditions. The use of ground processing of plasma moments instead of on‐board processing is crucial for the extraction of reliable measurements. Plain Language Summary: Space weather originates at the Sun and affects human life. An effective space weather monitor is required to detect severe space weather events and provide early warnings before such events arrive at Earth. The European Space Agency's (ESA's) Vigil mission will carry the Plasma Analyser (PLA) instrument to obtain measurements of the solar wind proton moments such as their number density, velocity, and temperature. We predict the expected performance of the PLA instrument by modeling its response to realistic solar wind conditions, which accounts for non‐equilibrium effects such as temperature anisotropy, proton beams, and α‐particles. We also study the impact of other non‐equilibrium distributions such as κ‐distributions (in the Appendix) to quantify the performance over a wide range of expected plasma conditions. We quantify the measurement accuracy by comparing the input and output parameters of the model and discuss possible improvements to the analysis of data from Vigil/PLA. Key Points: ESA's Vigil mission will measure the solar wind from the fifth Lagrange pointWe study the impact of non‐equilibrium plasma distributions on the performance of the Vigil/PLA instrumentUnder reasonable solar wind conditions, non‐equilibrium distributions can deteriorate onboard moments. Fitted moments are still reliable
- Subjects
EUROPEAN Space Agency; SOLAR wind; NONEQUILIBRIUM plasmas; WIND measurement; SPACE environment; LAGRANGIAN points; PROTON beams
- Publication
Space Weather: The International Journal of Research & Applications, 2024, Vol 22, Issue 2, p1
- ISSN
1539-4956
- Publication type
Article
- DOI
10.1029/2023SW003671