Quantification of ion scattering by solar-wind current sheets: Pitch-angle diffusion rates

Area of Science:

• Space Physics
• Plasma Physics
• Astrophysics

Background:

• Energetic particle transport in the heliosphere is affected by solar wind turbulence.
• Previous models often used idealized turbulence, neglecting coherent structures like current sheets.

Purpose of the Study:

• To quantify the role of solar wind current sheets in driving energetic particle pitch-angle scattering.
• To develop a framework for incorporating current sheet effects into particle transport models.

Main Methods:

• Developed an analytical Hamiltonian framework and test particle simulations.
• Incorporated observational data from ARTEMIS and Wind missions.
• Modeled particle dynamics through current sheets with realistic parameters.

Main Results:

• Scattering efficiency depends on current sheet shear angle, normal magnetic field component, and particle gyroradius to sheet thickness ratio.
• Observed large pitch-angle jumps and diffusive scattering.
• Found significant scattering rates for 100 keV to 1 MeV protons at 1 AU.

Conclusions:

• Solar wind current sheets are crucial for energetic particle scattering and transport in the heliosphere.
• Derived diffusion rates allow for more accurate global transport models.
• Highlights the importance of coherent structures in space and astrophysical plasmas.