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How Alfvén waves energize the solar wind: heat vs work
Jean C Perez1, Benjamin D G Chandran2, Kristopher G Klein3
1Department of Aerospace, Physics and Space Sciences, Florida Institute of Technology, Melbourne, Florida, USA.
Journal of Plasma Physics
|February 14, 2022
Summary
Alfvén waves (AWs) power the solar wind through heating and work. Simulations show heating is more effective than work below the Alfvén critical point, with significant energy transfer to particles.
Area of Science:
- Plasma Physics
- Heliophysics
- Astrophysics
Background:
- Solar wind is largely powered by Alfvén waves (AWs).
- AWs energize solar wind plasma via heating and work.
- Understanding energy transfer mechanisms is crucial for solar wind models.
Purpose of the Study:
- Investigate AW energy transfer to solar wind particles.
- Quantify heating and work fractions of AW power.
- Analyze mechanisms driving energy transfer in a fast solar wind stream.
Main Methods:
- High-resolution direct numerical simulations of reflection-driven AW turbulence (RDAWT).
- Simulations conducted in a fast solar wind stream from a coronal hole.
- Calculation of energy fractions transferred via heating (χH) and work (χW).
Main Results:
- Work transfer fraction (χW) at the Alfvén critical point (rA) is 0.15–0.3.
- Heating transfer fraction (χH) at rA is 0.5–0.7.
- Heating is more effective than work below rA due to AW dissipation over scale heights.
Conclusions:
- Alfvén wave heating is a dominant energy transfer mechanism in the inner solar wind.
- Proton magnetic moment increases with heliocentric distance due to heating in weaker magnetic fields.
- Simulations provide insights into AW energy dissipation and solar wind acceleration.
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