Shock Drift Acceleration of Electrons

Ball, Lewis; Melrose, D. B.

doi:10.1071/as01047

Cited by 93 publications

(114 citation statements)

References 43 publications

Supporting

Mentioning

111

Contrasting

Order By: Relevance

“…5. As pointed out in previous studies, particles cannot be reflected by the shock when θ Bn is near 90°(e.g., Holman & Pesses 1983;Ball & Melrose 2001). Now we examine the positions of energetic electrons as the shock reaches different heights.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…At quasiperpendicular shocks, electrons can be accelerated by gradient drift in the magnetic field at the shock along the motional electric field, known as shock drift acceleration (SDA, Armstrong et al 1985) or fast Fermi acceleration (Wu 1984). However, for a single reflection at a planar shock in the scatterfree limit, the energy gain has been shown to be very limited (e.g., Ball & Melrose 2001). Thus, multiple reflections at the shock are required for efficient acceleration.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electron Acceleration at a Coronal Shock Propagating Through a Large-Scale Streamer-Like Magnetic Field

Kong

Chen

Guo

et al. 2016

ApJ

View full text Add to dashboard Cite

Using a test-particle simulation, we investigate the effect of large-scale coronal magnetic fields on electron acceleration at an outward-propagating coronal shock with a circular front. The coronal field is approximated by an analytical solution with a streamer-like magnetic field featuring a partially open magnetic field and a current sheet at the equator atop the closed region. We show that the large-scale shock-field configuration, especially the relative curvature of the shock and the magnetic field line across which the shock is sweeping, plays an important role in the efficiency of electron acceleration. At low shock altitudes, when the shock curvature is larger than that of the magnetic field lines, the electrons are mainly accelerated at the shock flanks; at higher altitudes, when the shock curvature is smaller, the electrons are mainly accelerated at the shock nose around the top of closed field lines. The above process reveals the shift of the efficient electron acceleration region along the shock front during its propagation. We also find that, in general, the electron acceleration at the shock flank is not as efficient as that at the top of the closed field because a collapsing magnetic trap can be formed at the top. In addition, we find that the energy spectra of electrons are power-law-like, first hardening then softening with the spectral index varying in a range of −3 to −6. Physical interpretations of the results and implications for the study of solar radio bursts are discussed.

show abstract

Section: Simulation Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electron Acceleration at a Coronal Shock Propagating Through a Large-Scale Streamer-Like Magnetic Field

Kong

Chen

Guo

et al. 2016

ApJ

View full text Add to dashboard Cite

show abstract

“…It is important to note, though, that our strictly perpendicular shocks are superluminal, and hence a de-Hoffman-Teller frame does not exist, and injection into SDA should be suppressed (Ball & Melrose 2001).…”

Section: Structure Of the Forward Shockmentioning

confidence: 99%

Nonrelativistic Perpendicular Shocks Modeling Young Supernova Remnants: Nonstationary Dynamics and Particle Acceleration at Forward and Reverse Shocks

Wieland

Pohl

Niemiec

et al. 2016

ApJ

View full text Add to dashboard Cite

For parameters that are applicable to the conditions at young supernova remnants, we present results of twodimensional, three-vector (2D3V)particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at a  45 angle to the simulation plane to approximate three-dimensional (3D) physics. We developed an improved clean setup that uses the collision of two plasma slabs with different densities and velocities, leading to the development of two distinctive shocks and a contact discontinuity. The shock formation is mediated by Weibel-type filamentation instabilities that generate magnetic turbulence. Cyclic reformation is observed in both shocks with similar period, for which we note global variations due to shock rippling and local variations arising from turbulent current filaments. The shock rippling occurs on spatial and temporal scales produced by the gyro-motions of shock-reflected ions. The drift motion of electrons and ions is not a gradient drift, but is commensurate withÉ B drift. We observe a stable supra-thermal tail in the ion spectra, but no electron acceleration because the amplitude of the Buneman modes in the shock foot is insufficient for trapping relativistic electrons. We see no evidence of turbulent reconnection. A comparison with other twodimensional (2D) simulation results suggests that the plasma beta and the ion-to-electron mass ratio are not decisive for efficient electron acceleration, but the pre-acceleration efficacy might be reduced with respect to the 2D results once 3D effects are fully accounted for. Other microphysical factors may also play a part in limiting the amplitude of the Buneman waves or preventing the return of electrons to the foot region.

show abstract

“…Following the approach by Ball & Melrose (2001) and Mann & Klassen (2005), the shock drift acceleration is treated in the de Hoffmann-Teller frame, which is defined by removing the motional electric field. Note that the shock is also at rest in this frame.…”

Section: G Mannmentioning

confidence: 99%

Energetic electrons generated during solar flares

Mann

2015

J. Plasma Phys.

View full text Add to dashboard Cite

The Sun is a giant particle accelerator. During solar flares, magnetic field energy stored in the corona is suddenly released and transferred to local heating of the coronal plasma, mass motions (e.g. jets) and the generation of energetic particles, i.e. electrons, protons and heavy ions. Basically, a flare occurs as a local enhancement of the emission of electromagnetic radiation from the radio up to the γ -ray range on the Sun. That indicates the production of energetic electrons during flares. NASA's RHESSI mission has the aim to investigate electron acceleration processes by studying the Sun's X-ray and γ -ray emission with high spatial, temporal and spectral resolution, i.e. by means of imaging spectroscopy. A substantial part of the energy released during a flare is carried by these energetic electrons. Apart from them, solar energetic particles, i.e. protons and heavy ions, and coronal mass ejections play an important role in the energy budget of a flare. Here, we focus on electron acceleration. The way in which 10 36 electrons are accelerated up to energies beyond 30 keV is one of the open questions in solar physics. A flare is considered as the manifestation of magnetic reconnection in the solar corona. Which mechanisms lead to the production of energetic electrons in the magnetic reconnection region is discussed in this paper. Two of them are described in more detail.

show abstract

Shock Drift Acceleration of Electrons

Cited by 93 publications

References 43 publications

Electron Acceleration at a Coronal Shock Propagating Through a Large-Scale Streamer-Like Magnetic Field

Electron Acceleration at a Coronal Shock Propagating Through a Large-Scale Streamer-Like Magnetic Field

Nonrelativistic Perpendicular Shocks Modeling Young Supernova Remnants: Nonstationary Dynamics and Particle Acceleration at Forward and Reverse Shocks

Energetic electrons generated during solar flares

Contact Info

Product

Resources

About