The acceleration of electrons at perpendicular shocks and its implication for solar energetic particle events

Fan Guo, Joe Giacalone

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

We present a study of the acceleration of electrons at a perpendicular shock that propagates through a turbulentmagnetic field. The energization process of electrons is investigated by utilizing a combination of hybrid (kinetic ions and fluid electron) simulations and test-particle electron simulations. In this method, the motions of the test-particle electrons are numerically integrated in the time-dependent electric and magnetic fields generated by two-dimensional hybrid simulations. We show that large-scale magnetic fluctuations effect electrons in a number of ways and lead to efficient and rapid energization at the shock front. Since the electrons mainly follow along magnetic lines of force, the large-scale braiding of field lines in space allows the fast-moving electrons to interact with the shock front and get accelerated multiple times. Ripples in the shock front occurring at various scales will also contribute to the acceleration by mirroring the electrons. Our calculation shows that this process favors electron acceleration at perpendicular shocks. The acceleration efficiency is critically dependent on the turbulence amplitude and coherence length. We also discuss the implication of this study for solar energetic particles (SEPs) by comparing the acceleration of electrons with that of protons. Their correlation indicates that perpendicular shocks play an important role in SEP events.

Original languageEnglish (US)
Title of host publicationAIP Conference Proceedings
Pages93-99
Number of pages7
Volume1500
Edition1
DOIs
StatePublished - 2012
Event11th Annual International Astrophysics Conference on Space Weather: The Space Radiation Environment - Palm Springs, CA, United States
Duration: Mar 19 2012Mar 23 2012

Other

Other11th Annual International Astrophysics Conference on Space Weather: The Space Radiation Environment
CountryUnited States
CityPalm Springs, CA
Period3/19/123/23/12

Fingerprint

energetic particles
shock
electrons
shock fronts
lines of force
electron acceleration
simulation
ripples
turbulence
protons
electric fields
fluids
kinetics

Keywords

  • Acceleration of particles
  • cosmic rays
  • shock waves
  • turbulence

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

The acceleration of electrons at perpendicular shocks and its implication for solar energetic particle events. / Guo, Fan; Giacalone, Joe.

AIP Conference Proceedings. Vol. 1500 1. ed. 2012. p. 93-99.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Guo, F & Giacalone, J 2012, The acceleration of electrons at perpendicular shocks and its implication for solar energetic particle events. in AIP Conference Proceedings. 1 edn, vol. 1500, pp. 93-99, 11th Annual International Astrophysics Conference on Space Weather: The Space Radiation Environment, Palm Springs, CA, United States, 3/19/12. https://doi.org/10.1063/1.4768750
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AB - We present a study of the acceleration of electrons at a perpendicular shock that propagates through a turbulentmagnetic field. The energization process of electrons is investigated by utilizing a combination of hybrid (kinetic ions and fluid electron) simulations and test-particle electron simulations. In this method, the motions of the test-particle electrons are numerically integrated in the time-dependent electric and magnetic fields generated by two-dimensional hybrid simulations. We show that large-scale magnetic fluctuations effect electrons in a number of ways and lead to efficient and rapid energization at the shock front. Since the electrons mainly follow along magnetic lines of force, the large-scale braiding of field lines in space allows the fast-moving electrons to interact with the shock front and get accelerated multiple times. Ripples in the shock front occurring at various scales will also contribute to the acceleration by mirroring the electrons. Our calculation shows that this process favors electron acceleration at perpendicular shocks. The acceleration efficiency is critically dependent on the turbulence amplitude and coherence length. We also discuss the implication of this study for solar energetic particles (SEPs) by comparing the acceleration of electrons with that of protons. Their correlation indicates that perpendicular shocks play an important role in SEP events.

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