Plasma density and magnetic field fluctuations in the ion gyro-frequency range near the diamagnetic cavity of comet 67P - INSU - Institut national des sciences de l'Univers Access content directly
Conference Papers Year : 2019

Plasma density and magnetic field fluctuations in the ion gyro-frequency range near the diamagnetic cavity of comet 67P

Elias Odelstad
  • Function : Author
Anders Eriksson
Mats André
Daniel Graham
  • Function : Author
Charlotte Goetz
  • Function : Author
Erik Vigren
  • Function : Author
Kei Masunaga
Hans Nilsson
  • Function : Author
Tomas Karlsson
  • Function : Author

Abstract

We report the detection of large-amplitude, quasi-harmonic density-fluctuations with associated magnetic field oscillations in the region surrounding the diamagnetic cavity of comet 67P. Typical frequencies are ∼0.1 Hz, corresponding to ∼10 times the water and ≲0.5 times the proton gyro-frequencies, respectively. Magnetic field oscillations are not always clearly observed in association to these density fluctuations, but when they are, they consistently have wave vectors perpendicular to the background magnetic field, with the principal axis of polarization close to field-aligned and with a ∼90∘ phase lag w.r.t. the density fluctuations. The fluctuations are observed in association with asymmetric plasma and magnetic field enhancements previously found in the region surrounding the diamagnetic cavity, occurring predominantly on their descending slopes. We speculate that they are Ion Bernstein waves (IBWs) excited by the drift-cyclotron instability resulting from strong plasma inhomogeneities in the region surrounding the diamagnetic cavity.
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Dates and versions

insu-03563842 , version 1 (10-02-2022)

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Elias Odelstad, Anders Eriksson, Mats André, Daniel Graham, Hugo Breuillard, et al.. Plasma density and magnetic field fluctuations in the ion gyro-frequency range near the diamagnetic cavity of comet 67P. 21st EGU General Assembly, Apr 2019, Vienne, Austria. ⟨insu-03563842⟩
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