Four Solar Orbiter interplanetary shocks show energetic particle pressure dominating upstream, indicating particle-mediated modification of collisionless shocks.
Simulations of Ion Acceleration at Non-relativistic Shocks. II. Magnetic Field Amplification
4 Pith papers cite this work. Polarity classification is still indexing.
abstract
We use large hybrid simulations to study ion acceleration and generation of magnetic turbulence due to the streaming of particles that are self-consistently accelerated at non-relativistic shocks. When acceleration is efficient, we find that the upstream magnetic field is significantly amplified. The total amplification factor is larger than 10 for shocks with Alfv\'enic Mach number $M=100$, and scales with the square root of $M$. The spectral energy density of excited magnetic turbulence is determined by the energy distribution of accelerated particles, and for moderately-strong shocks ($M\lesssim30$) agrees well with the prediction of resonant streaming instability, in the framework of quasilinear theory of diffusive shock acceleration. For $M\gtrsim30$, instead, Bell's non-resonant hybrid (NRH) instability is predicted and found to grow faster than resonant instability. NRH modes are excited far upstream by escaping particles, and initially grow without disrupting the current, their typical wavelengths being much shorter than the current ions' gyroradii. Then, in the nonlinear stage, most unstable modes migrate to larger and larger wavelengths, eventually becoming resonant in wavelength with the driving ions, which start diffuse. Ahead of strong shocks we distinguish two regions, separated by the free-escape boundary: the far upstream, where field amplification is provided by the current of escaping ions via NRH instability, and the shock precursor, where energetic particles are effectively magnetized, and field amplification is provided by the current in diffusing ions. The presented scalings of magnetic field amplification enable the inclusion of self-consistent microphysics into phenomenological models of ion acceleration at non-relativistic shocks.
years
2026 4verdicts
UNVERDICTED 4representative citing papers
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This review summarizes the basic principles of electron transport in inhomogeneous and tangled magnetic fields through gyro-centre trajectories, kinetic instabilities, trapping, and diffusion processes.
citing papers explorer
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Energetic particle-mediated interplanetary shocks observed by Solar Orbiter
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LEGGOS presents a uniform framework that jointly models lensing, photometry, and integral-field spectroscopy to disentangle stellar populations in clumps of high-redshift lensed galaxies.
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Transport of electrons in tangled magnetic fields
This review summarizes the basic principles of electron transport in inhomogeneous and tangled magnetic fields through gyro-centre trajectories, kinetic instabilities, trapping, and diffusion processes.