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Updated: May 18, 2026
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Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
Magnetic moment nonconservation in magnetohydrodynamic turbulence models
S Dalena1, A Greco, A F Rappazzo
1Dipartimento di Fisica, Università della Calabria, I-87036 Cosenza, Italy.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 26, 2012
Summary
The magnetic moment is not constant in turbulent astrophysical plasmas, affecting particle acceleration. Simulations show pitch angle and magnetic moment changes are linked, leading to isotropization and diffusion under strong magnetic fluctuations.
Area of Science:
- Plasma Physics
- Astrophysics
- Space Physics
Background:
- Adiabatic theory assumptions fail with sharp field gradients or magnetohydrodynamic turbulence.
- The magnetic moment (μ) constancy is violated in these conditions.
- This has implications for particle acceleration in astrophysical phenomena.
Purpose of the Study:
- Derive expressions for magnetic moment trapping width (Δμ) and bounce frequency (ω(b)).
- Investigate magnetic moment behavior during resonance overlapping and broadband spectrum interactions.
- Analyze the relationship between magnetic moment changes and pitch angle isotropization.
Main Methods:
- Derivation of magnetic moment trapping width and bounce frequency from resonant wave-particle interactions.
- Test-particle simulations of ion interactions with electromagnetic waves.
- Simulations involving resonance overlapping and broadband slab spectrum interactions.
Main Results:
- Magnetic moment and pitch angle changes are correlated at low magnetic fluctuation levels (δB/B(0) = 10⁻³–10⁻²).
- Stochasticity emerges at intermediate fluctuations, causing pitch angle isotropization and a one-sided magnetic moment distribution tail.
- Strong fluctuations lead to complete isotropization, spatial diffusion, and magnetic moment behavior linked to spatial diffusion.
Conclusions:
- The magnetic moment is not conserved in turbulent plasmas, impacting particle dynamics.
- Resonance overlapping and broadband turbulence drive stochasticity and isotropization of particle distributions.
- Spatial diffusion becomes significant under strong magnetic fluctuations, influencing particle behavior.
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