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Models of Collisionless Quasineutral Solar Wind Current Sheets
Sophie Boswell1, Thomas Neukirch1, Anton Artemyev2
1School of Mathematics and Statistics, University of St. Andrews, St. Andrews, UK.
Solar Physics
|October 16, 2025
Summary
Solar wind current sheets exhibit asymmetric density and temperature variations. A new model with modified electron distribution functions reveals substructure within these plasma sheets.
Area of Science:
- Space Physics
- Plasma Physics
- Astrophysics
Background:
- In situ solar wind measurements reveal kinetic scale current sheets.
- These sheets are often force-free with plasma beta of order one.
- Observed particle density and temperature asymmetries across current sheets were previously modeled.
Purpose of the Study:
- To modify existing force-free collisionless current sheet models.
- To investigate the effect of an additional term in the electron distribution function only.
- To analyze the resulting plasma density and electric field substructure.
Main Methods:
- Modification of self-consistent force-free collisionless current sheet models.
- Inclusion of an additional term in the electron distribution function, keeping ions Maxwellian.
- Numerical solution of the nonlinear quasineutrality condition alongside Ampère's law.
Main Results:
- The magnetic field remains approximately force-free.
- A non-zero quasineutral electric field arises.
- An additional spatial substructure of plasma density is observed within the current sheet.
Conclusions:
- The modified model provides insights into current sheet dynamics.
- Theoretical findings may relate to observed current sheet substructures.
- Asymmetric electron distributions can create density substructures in solar wind current sheets.
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