TY - JOUR
T1 - Effect of Upstream ULF Waves on the Energetic Ion Diffusion at the Earth's Foreshock. II. Observations
AU - Kis, Arpad
AU - Matsukiyo, Shuichi
AU - Otsuka, Fumiko
AU - Hada, Tohru
AU - Lemperger, Istvan
AU - Dandouras, Iannis
AU - Barta, Veronika
AU - Facsko, Gabor
N1 - Funding Information:
The authors wish to thank for the support provided by the Kyushu University, the Hungarian Academy of Sciences, the OTKA PD-78674, NKFIH NN 116446, and the HAS-JSPS NKM-95/2016 bilateral project. The study was partially supported by Grant-in-Aid for JSPS Research Fellow 15J40063 (F.O.) and JSPS Bilateral Joint Research Project (S.M.). We especially thank Manfred Scholer and Berndt Klecker for the fruitful conversations on the topic of the study. We would like to express our gratitude for the data provided by the CSA (Cluster Science Archive) and the CLWeb data visualization tool written by Emmanuel Penou, IRAP. Last, but not least, I (A.K.) would like to thank Nádas Mihály, my dear friend and mentor, who supported and encouraged me from the very beginning.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/8/20
Y1 - 2018/8/20
N2 - 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.
AB - 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.
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U2 - 10.3847/1538-4357/aad08c
DO - 10.3847/1538-4357/aad08c
M3 - Article
AN - SCOPUS:85052388197
SN - 0004-637X
VL - 863
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 136
ER -