Particle-in-Cell Simulations of Particle Energization via Shock Drift Acceleration From Low Mach Number Quasi-Perpendicular Shocks in Solar Flares

Park, Jaehong; Ren, C.; Workman, Jared C.; Blackman, Eric G.

doi:10.1088/0004-637x/765/2/147

Cited by 34 publications

(38 citation statements)

References 37 publications

(82 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Park et al. 2013; Guo, Sironi & Narayan 2014 a , b ; Park, Caprioli & Spitkovsky 2015; Xu, Spitkovsky & Caprioli 2020), this study is the first direct diagnosis of the energy transfer in a collisionless shock in phase space and identification of the velocity-space signatures of shock-drift acceleration and adiabatic heating.…”

Section: Introductionmentioning

confidence: 75%

A field–particle correlation analysis of a perpendicular magnetized collisionless shock

et al. 2021

View full text Add to dashboard Cite

Using the field–particle correlation technique, we examine the particle energization in a three-dimensional (one spatial dimension and two velocity dimensions; 1D-2V) continuum Vlasov–Maxwell simulation of a perpendicular magnetized collisionless shock. The combination of the field–particle correlation technique with the high-fidelity representation of the particle distribution function provided by a direct discretization of the Vlasov equation allows us to ascertain the details of the exchange of energy between the electromagnetic fields and the particles in phase space. We identify the velocity-space signatures of shock-drift acceleration of the ions and adiabatic heating of the electrons arising from the perpendicular collisionless shock by constructing a simplified model with the minimum ingredients necessary to produce the observed energization signatures in the self-consistent Vlasov–Maxwell simulation. We are thus able to completely characterize the energy transfer in the perpendicular collisionless shock considered here and provide predictions for the application of the field–particle correlation technique to spacecraft measurements of collisionless shocks.

show abstract

Section: Introductionmentioning

confidence: 75%

A field–particle correlation analysis of a perpendicular magnetized collisionless shock

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Significant effort has been put into using PIC simulations to study electron injection in different shock regimes (see [211], [212], [213]) and a few injection mechanisms have been proposed. In the low M A (∼ 3), high β e (larger than ∼ 20) regime, relevant to shocks in galaxy clusters and solar flares, it has been shown that significant non-thermal electron acceleration can be obtained via shock drift acceleration (SDA; [214], [213], [215]). In quasi-perpendicular shocks, the electrons can gain energy from the motional electric field of the upstream medium (perpendicular to the upstream magnetic field).…”

Section: Numerical Simulationsmentioning

confidence: 99%

The microphysics of collisionless shock waves

et al. 2016

View full text Add to dashboard Cite

Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

show abstract

“…Next we ruled out the Earth's bow shock as a source by examining the following concepts. First, the two most viable shock acceleration mechanisms for electrons have the highest efficiencies in the quasi-perpendicular (θ Bn > 45 • ) region of the shock 9,16 . Second, due to a higher mobility along versus across Bo, any energetic electron distribution observed several Earth radii (i.e., tens to hundreds of Larmor radii) away from the source would be highly anisotropic along Bo, as previously reported 26 , inconsistent with our observations (e.g., Figs 2a-2c).…”

mentioning

confidence: 99%

Relativistic Electrons Produced by Foreshock Disturbances Observed Upstream of Earth’s Bow Shock

et al. 2016

View full text Add to dashboard Cite

Foreshock disturbances -large-scale (∼1000 km to >30,000 km), solitary (∼5-10 per day, transient (lasting ∼10s of seconds to several minutes)) structures 1,2 -generated by suprathermal (>100 eV to 100s of keV) ions 3,4 arise upstream of Earth's bow shock formed by the solar wind colliding with the Earth's magnetosphere. They have recently been found to accelerate ions to energies of several keV 5,6 . One type was found to have a distinct suprathermal electron population with energies >70 keV, which was attributed to a magnetospheric origin 7 . Although electrons in Saturn's high Mach number (M > 40) bow shock can be accelerated to relativistic energies (nearly 1000 keV) 8 , it has hitherto been thought impossible to accelerate electrons at the much weaker (M < 20) Earth's bow shock beyond a few 10s of keV 9 . Here we report observations of electrons energized by foreshock disturbances from 10s of eV up to at least ∼300 keV. We observe a single isotropic power-law from 100s of eV to 100s of keV, unlike previous studies 7 . All previous observations of energetic foreshock electrons have been attributed to escaping magnetospheric particles 7,10,11 or solar events 12 . We observe no solar activity and the single isotropic power-law cannot be explained by any magnetospheric source. Further, current theories of ion acceleration in foreshock disturbances cannot account for electrons accelerated to the observed relativistic energies [13][14][15][16][17][18] . These electrons are clearly coming from the disturbances, leaving us with no explanation for the acceleration mechanism.We examine in detail particle velocity distribution functions measured by the low energy electron/total ion electrostatic analyzers 19 The disturbances occur in the ion foreshock 3,4 region upstream of the quasi-parallel bow shock, where the shock normal angle (θ Bn ) between the upstream quasi-static magnetic field (Bo) and the shock normal vector satisfies θ Bn < 45 • . We focused on observations near short large-amplitude magnetic structures 4 , hot flow anomalies 1 , and foreshock bubbles 2 . During the four orbital passes examined in detail, we identified 30 foreshock disturbances, 10 of which had clear energetic electron enhancements (five at short large-amplitude magnetic structures, two at hot flow anomalies, and three at foreshock bubbles). See Extended Data Fig. 1 for spacecraft orbits and Methods for further details of foreshock disturbances.We observe energetic (≥30 keV) electron enhancements as short duration (∼10s of seconds to few minutes) enhancements in the electron fluxes above background by factors of ∼10-200 (Fig. 1). They are localized to the large fluctuations in Bo (Figs 1a-1c) within the foreshock disturbances. The electron flux-time profiles for energies from ∼0.25 to >200 keV show no energy dispersion, i.e., fluxes increase at all energies simultaneously (Figs 1g-1i and 1m-1o). The low energy electron and ion (Figs 1j-1l) data look qualitatively similar for disturbances with and without (Extended Data Fig. 2) energetic ...

show abstract

Particle-in-Cell Simulations of Particle Energization via Shock Drift Acceleration From Low Mach Number Quasi-Perpendicular Shocks in Solar Flares

Cited by 34 publications

References 37 publications

A field–particle correlation analysis of a perpendicular magnetized collisionless shock

A field–particle correlation analysis of a perpendicular magnetized collisionless shock

The microphysics of collisionless shock waves

Relativistic Electrons Produced by Foreshock Disturbances Observed Upstream of Earth’s Bow Shock

Contact Info

Product

Resources

About