Simulation of a perpendicular bow shock

Leroy, M.; Goodrich, C. C.; Winske, D.; Wu, Chao; Papadopoulos, K.

doi:10.1029/gl008i012p01269

Cited by 207 publications

(161 citation statements)

References 13 publications

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“…One prominent path is ion reflection at the shock front. Electric and magnetic forces in the shock transition layer are believed to cause a nearspecular reflection of a fraction of the upstream flow, resulting in cold reflected ion beams, bunched in gyrophase (Leroy et al 1981(Leroy et al , 1982Gosling et al 1982;Gosling & Robson 1985). In perfect specular reflection, the ion velocity component normal to the shock is reversed, while that transverse to the shock normal is preserved.…”

Section: Introductionmentioning

confidence: 99%

Ion Acceleration at the Quasi-Parallel Bow Shock: Decoding the Signature of Injection

Sundberg

Haynes

Burgess

et al. 2016

ApJ

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Collisionless shocks are efficient particle accelerators. At Earth, ions with energies exceeding 100 keV are seen upstream of the bow shock when the magnetic geometry is quasi-parallel, and large-scale supernova remnant shocks can accelerate ions into cosmic-rayenergies. This energization is attributed to diffusive shock acceleration;however, for this process to become active, the ions must first be sufficiently energized. How and where this initial acceleration takes place has been one of the key unresolved issues in shock acceleration theory. Using Cluster spacecraft observations, we study the signatures of ion reflection events in the turbulent transition layer upstream of the terrestrial bow shock, and with the support of a hybrid simulation of the shock, we show that these reflection signatures are characteristic of the first step in the ion injection process. These reflection events develop in particular in the region where the trailing edge of large-amplitude upstream waves intercept the local shock ramp and the upstream magnetic field changes from quasi-perpendicular to quasi-parallel. The dispersed ion velocity signature observed can be attributed to a rapid succession of ion reflections at this wave boundary. After the ions' initial interaction with the shock, they flow upstream along the quasi-parallel magnetic field. Each subsequent wavefront in the upstream region will sweep the ions back toward the shock, where they gain energy with each transition between the upstream and the shock wave frames. Within three to five gyroperiods, some ions have gained enough parallel velocity to escape upstream, thus completing the injection process.

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Section: Introductionmentioning

confidence: 99%

Ion Acceleration at the Quasi-Parallel Bow Shock: Decoding the Signature of Injection

Sundberg

Haynes

Burgess

et al. 2016

ApJ

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“…This makes it difficult to perform multidimensional simulations even with present-day supercomputers. In this letter, we first attempt to perform a full particle simulation of a collisionless shock in the shock rest frame: the collisionless shock is excited by using the "relaxation method" which was used in hybrid code simulations in 1980s (Leroy et al, 1981(Leroy et al, , 1982Kan and Swift, 1983). This method has not been used in full particle simulations due to several difficulties in numerical techniques.…”

Section: Introductionmentioning

confidence: 99%

Full particle simulation of a perpendicular collisionless shock: A shock-rest-frame model

Umeda

Yamazaki

2006

Earth Planet Sp

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The full kinetic dynamics of a perpendicular collisionless shock is studied by means of a one-dimensional electromagnetic full particle simulation. The present simulation domain is taken in the shock rest frame in contrast to the previous full particle simulations of shocks. Preliminary results show that the downstream state falls into a unique cyclic reformation state for a given set of upstream parameters through the self-consistent kinetic processes.

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“…This is not the number density of the ambient gas, but it is reasonable to expect that they may be related. It is known that high-Mach shocks dissipate their energy by reflecting a fraction of the particles incident on the shock, creating suprathermal "specularly reflected" ions (Leroy et al 1981;Sckopke et al 1983;Winske 1985). It is reasonable to expect these to be further accelerated by the shock (e.g., Giacalone 2005b).…”

Section: Resultsmentioning

confidence: 99%

The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field

Giacalone

2017

ApJ

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We investigate the physics of charged-particle acceleration at spherical shocks moving into a uniform plasma containing a turbulent magnetic field with a uniform mean. This has applications to particle acceleration at astrophysical shocks, most notably, to supernovae blast waves. We numerically integrate the equations of motion of a large number of test protons moving under the influence of electric and magnetic fields determined from a kinematically defined plasma flow associated with a radially propagating blast wave. Distribution functions are determined from the positions and velocities of the protons. The unshocked plasma contains a magnetic field with a uniform mean and an irregular component having a Kolmogorov-like power spectrum. The field inside the blast wave is determined from Maxwell's equations. The angle between the average magnetic field and unit normal to the shock varies with position along its surface. It is quasi-perpendicular to the unit normal near the sphere's equator, and quasi-parallel to it near the poles. We find that the highest intensities of particles, accelerated by the shock, are at the poles of the blast wave. The particles "collect" at the poles as they approximately adhere to magnetic field lines that move poleward from their initial encounter with the shock at the equator, as the shock expands. The field lines at the poles have been connected to the shock the longest. We also find that the highestenergy protons are initially accelerated near the equator or near the quasi-perpendicular portion of the shock, where the acceleration is more rapid.

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Simulation of a perpendicular bow shock

Cited by 207 publications

References 13 publications

Ion Acceleration at the Quasi-Parallel Bow Shock: Decoding the Signature of Injection

Ion Acceleration at the Quasi-Parallel Bow Shock: Decoding the Signature of Injection

Full particle simulation of a perpendicular collisionless shock: A shock-rest-frame model

The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field

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