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In Situ Signature of Cyclotron Resonant Heating in the Solar Wind
Trevor A Bowen1, Benjamin D G Chandran2, Jonathan Squire3
1Space Sciences Laboratory, University of California, Berkeley, California 94720-7450, USA.
Physical Review Letters
|October 28, 2022
Summary
Parker Solar Probe data reveals ion-cyclotron waves directly linked to resonant damping in proton velocity distributions. This confirms significant solar wind heating via cyclotron resonance, a key process in space plasma physics.
Area of Science:
- Space Physics
- Plasma Astrophysics
- Solar Physics
Background:
- Dissipation of magnetized turbulence is crucial for energy transfer in astrophysical plasmas.
- Collisionless heating mechanisms in the solar corona and wind lack direct observational constraints.
- Previous observations suggested cyclotron resonant heating and the presence of cyclotron waves.
Purpose of the Study:
- To directly connect ion-cyclotron waves to signatures of resonant damping in proton velocity distributions.
- To quantify the heating rate in the solar wind due to these processes.
- To provide observational evidence for cyclotron resonance as a solar wind heating mechanism.
Main Methods:
- Utilizing Parker Solar Probe observations of in-situ magnetic fields and ion velocity distributions.
- Applying the framework of quasilinear theory to analyze wave-particle interactions.
- Correlating observed cyclotron waves with signatures of resonant damping in proton velocity distributions.
Main Results:
- Direct observational link established between ion-cyclotron waves and resonant damping signatures.
- Proton velocity distributions show absorption of cyclotron wave energy.
- Calculated a significant solar wind heating rate of 10^-14 W/m^3.
Conclusions:
- Quasilinear evolution of proton velocity distributions explains the absorption of cyclotron waves.
- Cyclotron resonance is confirmed as a significant heating mechanism for the solar wind.
- Provides crucial observational constraints on collisionless dissipation processes in space plasmas.
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