Effect of Upstream ULF Waves on the Energetic Ion Diffusion at the Earth's Foreshock. II. Observations

Arpad Kis, Shuichi Matsukiyo, Fumiko Otsuka, Tohru Hada, Istvan Lemperger, Iannis Dandouras, Veronika Barta, Gabor Facsko

Research output: Contribution to journalArticle

Abstract

This study reports observations of energetic ions upstream of the Earth's quasi-parallel bow shock by Cluster at times when interspacecraft separation distances were large. We analyze two individual upstream ion events during high solar wind velocity conditions to compare the spatial evolution of partial energetic ion densities in front of the Earth's bow shock along the magnetic field line. Using a bow shock model, we determine the distance of SC1 and SC3 to the bow shock surface parallel to the magnetic field. The CIS-HIA instrument on board Cluster provides partial energetic ion densities in four energy channels between 10 and 32 keV. Using the differences of the partial energetic ion densities observed on SC1 and SC3, and the distances of the spacecraft to the bow shock, we determine the spatial gradient of partial energetic ion densities at various distances from the bow shock. We show, for the first time, that the e-folding distance and the diffusion coefficient of the diffuse ions become unusually small when these ions interact with high-intensity waves generated by a strong field-aligned beam.

Original languageEnglish
Article number136
JournalAstrophysical Journal
Volume863
Issue number2
DOIs
Publication statusPublished - Aug 20 2018

Fingerprint

foreshock
bows
upstream
energetics
shock
ion
ions
solar wind velocity
Commonwealth of Independent States
magnetic field
magnetic fields
folding
effect
spacecraft
diffusion coefficient
solar wind
gradients
wind velocity

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Effect of Upstream ULF Waves on the Energetic Ion Diffusion at the Earth's Foreshock. II. Observations. / Kis, Arpad; Matsukiyo, Shuichi; Otsuka, Fumiko; Hada, Tohru; Lemperger, Istvan; Dandouras, Iannis; Barta, Veronika; Facsko, Gabor.

In: Astrophysical Journal, Vol. 863, No. 2, 136, 20.08.2018.

Research output: Contribution to journalArticle

Kis, Arpad ; Matsukiyo, Shuichi ; Otsuka, Fumiko ; Hada, Tohru ; Lemperger, Istvan ; Dandouras, Iannis ; Barta, Veronika ; Facsko, Gabor. / Effect of Upstream ULF Waves on the Energetic Ion Diffusion at the Earth's Foreshock. II. Observations. In: Astrophysical Journal. 2018 ; Vol. 863, No. 2.
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