Jet front-driven mirror modes and shocklets in the near-Earth flow-braking region

Bertalan Zieger; Alessandro Retinö; Rumi Nakamura; Wolfgang Baumjohann; Andris Vaivads; Yuri Khotyaintsev

doi:10.1029/2011GL049746

Jet front-driven mirror modes and shocklets in the near-Earth flow-braking region

Bertalan Zieger
, Alessandro Retinö
, Rumi Nakamura
, Wolfgang Baumjohann
, Andris Vaivads
, Yuri Khotyaintsev

Research output: Contribution to journal › Article › peer-review

Abstract

We investigate the small-scale structure of jet fronts through a case study of multi-spacecraft Cluster observations in the near-Earth flow-braking region at ∼-10 R_E. We find that the interaction between the earthward moving fast plasma jet and the high-β ambient plasma in the plasma sheet results in magnetic pileup and compression ahead of the jet and rarefaction trailing the jet. It is shown that mirror-mode structures of ion gyroradius scale develop within the pileup region due to the observed ion temperature anisotropy (T_i⊥ > T). We suggest that the growth of these mirror modes is driven by the perpendicular total pressure perturbation (Δp_⊥) generated by the braking jet. When Δp _⊥ becomes too large, the mirror-mode structure cannot maintain pressure balance any longer, and consequently a shocklet is formed in the pileup region ahead of the jet front. We present the first evidence for such a kinetic shocklet in the flow-braking region.

Original language	English
Article number	L22103
Journal	Geophysical Research Letters
Volume	38
Issue number	22
DOIs	https://doi.org/10.1029/2011GL049746
Publication status	Published - 1 Nov 2011

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title = "Jet front-driven mirror modes and shocklets in the near-Earth flow-braking region",

abstract = "We investigate the small-scale structure of jet fronts through a case study of multi-spacecraft Cluster observations in the near-Earth flow-braking region at ∼-10 RE. We find that the interaction between the earthward moving fast plasma jet and the high-β ambient plasma in the plasma sheet results in magnetic pileup and compression ahead of the jet and rarefaction trailing the jet. It is shown that mirror-mode structures of ion gyroradius scale develop within the pileup region due to the observed ion temperature anisotropy (Ti⊥ > T). We suggest that the growth of these mirror modes is driven by the perpendicular total pressure perturbation (Δp⊥) generated by the braking jet. When Δp ⊥ becomes too large, the mirror-mode structure cannot maintain pressure balance any longer, and consequently a shocklet is formed in the pileup region ahead of the jet front. We present the first evidence for such a kinetic shocklet in the flow-braking region.",

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T1 - Jet front-driven mirror modes and shocklets in the near-Earth flow-braking region

AU - Zieger, Bertalan

AU - Retinö, Alessandro

AU - Nakamura, Rumi

AU - Baumjohann, Wolfgang

AU - Vaivads, Andris

AU - Khotyaintsev, Yuri

PY - 2011/11/1

Y1 - 2011/11/1

N2 - We investigate the small-scale structure of jet fronts through a case study of multi-spacecraft Cluster observations in the near-Earth flow-braking region at ∼-10 RE. We find that the interaction between the earthward moving fast plasma jet and the high-β ambient plasma in the plasma sheet results in magnetic pileup and compression ahead of the jet and rarefaction trailing the jet. It is shown that mirror-mode structures of ion gyroradius scale develop within the pileup region due to the observed ion temperature anisotropy (Ti⊥ > T). We suggest that the growth of these mirror modes is driven by the perpendicular total pressure perturbation (Δp⊥) generated by the braking jet. When Δp ⊥ becomes too large, the mirror-mode structure cannot maintain pressure balance any longer, and consequently a shocklet is formed in the pileup region ahead of the jet front. We present the first evidence for such a kinetic shocklet in the flow-braking region.

AB - We investigate the small-scale structure of jet fronts through a case study of multi-spacecraft Cluster observations in the near-Earth flow-braking region at ∼-10 RE. We find that the interaction between the earthward moving fast plasma jet and the high-β ambient plasma in the plasma sheet results in magnetic pileup and compression ahead of the jet and rarefaction trailing the jet. It is shown that mirror-mode structures of ion gyroradius scale develop within the pileup region due to the observed ion temperature anisotropy (Ti⊥ > T). We suggest that the growth of these mirror modes is driven by the perpendicular total pressure perturbation (Δp⊥) generated by the braking jet. When Δp ⊥ becomes too large, the mirror-mode structure cannot maintain pressure balance any longer, and consequently a shocklet is formed in the pileup region ahead of the jet front. We present the first evidence for such a kinetic shocklet in the flow-braking region.

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JF - Geophysical Research Letters

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Jet front-driven mirror modes and shocklets in the near-Earth flow-braking region

Abstract

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