Magnetic field amplification by shocks in turbulent fluids

Research output: Contribution to journalArticle

179 Citations (Scopus)

Abstract

We consider the effect of preexisting, large-scale, broadband turbulent density fluctuations on propagating hydromagnetic shock waves. We present results from several numerical simulations that solve the two-dimensional magnetohydrodynamic equations. In our simulations, a plasma containing large-scale, low-amplitude density and magnetic field turbulence is forced to flow into a rigid wall, forming a shock wave. We find that the density fluctuations not only distort the shape of the shock front and lead to a turbulent postshock fluid, but they also produce a number of important changes in the postshock magnetic field. The average downstream magnetic field is increased significantly, and large fluctuations in the magnetic vector occur, with the maximum field strength reaching levels such that magnetic stresses are important in the postshock region. The downstream field enhancement can be understood in terms of the stretching and forcing together of the magnetic field entrained within the turbulent fluid of the postshock flow. We suggest that these effects of the density fluctuations on the magnetic field are observed in astrophysical shock waves such as supernova blast waves and the heliospheric termination shock.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume663
Issue number1 II
DOIs
StatePublished - Jul 1 2007

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amplification
shock
magnetic field
shock wave
fluid
fluids
shock waves
magnetic fields
magnetohydrodynamics
shock fronts
blasts
simulation
supernovae
field strength
astrophysics
turbulence
broadband
plasma
augmentation
effect

Keywords

  • Magnetic fields
  • Shock waves
  • Turbulence

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Magnetic field amplification by shocks in turbulent fluids. / Giacalone, Joe; Jokipii, J. Randy.

In: Astrophysical Journal, Vol. 663, No. 1 II, 01.07.2007.

Research output: Contribution to journalArticle

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