Evolution of a typical ion-scale magnetic flux rope caused by thermal pressure enhancement

Teh Wai Leong, T. K M Nakamura, R. Nakamura, W. Baumjohann, C. T. Russell, C. Pollock, P. A. Lindqvist, R. E. Ergun, J. L. Burch, R. B. Torbert, B. L. Giles

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

With high time-resolution field and plasma measurements by the Magnetospheric Multiscale spacecraft, interior fine structures of two ion-scale magnetic flux ropes (~5 and ~11 ion inertial length radius) separated by ~14 s are resolved. These two ion-scale flux ropes (FR1 and FR2) show non-frozen-in ion behavior and consist of a strong axial magnetic field at the reversal of the negative-then-positive bipolar field component. The negative bipolar field component of the FR2 is found to be depressed, where magnetic pressure and total pressure decrease, but ion and electron thermal pressures increase, a feature akin to a crater-like flux rope. The pressure enhancement is due to the magnetosheath plasma feeding into the flux rope along the field lines. Magnetic field draping and energetic electrons are also observed in the trailing part of the FR2. The ratio of perpendicular and parallel currents indicates that the FR1 appears force-free but the FR2 seems not. Moreover, the FR2 is time-dependent as a result of a low correlation coefficient (CC = 0.75) for the derivation of the deHoffmann-Teller frame using the direct measured electric fields, while the FR1 is in quasi-steady conditions (CC = 0.94). It is concluded that the crater formation within the FR2 can be interpreted by the analytical flux rope simulation as the evolution of typical flux rope to crater-like one due to the thermal pressure enhancement, which could be induced by the depression of transverse magnetic fields of the flux rope.

Original languageEnglish
Pages (from-to)2040-2050
Number of pages11
JournalJournal of Geophysical Research: Space Physics
Volume122
Issue number2
DOIs
Publication statusPublished - 1 Feb 2017

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ropes
Magnetic flux
magnetic flux
Ions
ions
heat
Fluxes
ion
augmentation
crater
craters
magnetic fields
magnetic field
Magnetic fields
plasma
electron
electrons
magnetosheath
Plasmas
electric field

Keywords

  • magnetic flux ropes
  • magnetopause

ASJC Scopus subject areas

  • Geophysics
  • Oceanography
  • Forestry
  • Ecology
  • Aquatic Science
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Cite this

Wai Leong, T., Nakamura, T. K. M., Nakamura, R., Baumjohann, W., Russell, C. T., Pollock, C., ... Giles, B. L. (2017). Evolution of a typical ion-scale magnetic flux rope caused by thermal pressure enhancement. Journal of Geophysical Research: Space Physics, 122(2), 2040-2050. https://doi.org/10.1002/2016JA023777

Evolution of a typical ion-scale magnetic flux rope caused by thermal pressure enhancement. / Wai Leong, Teh; Nakamura, T. K M; Nakamura, R.; Baumjohann, W.; Russell, C. T.; Pollock, C.; Lindqvist, P. A.; Ergun, R. E.; Burch, J. L.; Torbert, R. B.; Giles, B. L.

In: Journal of Geophysical Research: Space Physics, Vol. 122, No. 2, 01.02.2017, p. 2040-2050.

Research output: Contribution to journalArticle

Wai Leong, T, Nakamura, TKM, Nakamura, R, Baumjohann, W, Russell, CT, Pollock, C, Lindqvist, PA, Ergun, RE, Burch, JL, Torbert, RB & Giles, BL 2017, 'Evolution of a typical ion-scale magnetic flux rope caused by thermal pressure enhancement', Journal of Geophysical Research: Space Physics, vol. 122, no. 2, pp. 2040-2050. https://doi.org/10.1002/2016JA023777
Wai Leong, Teh ; Nakamura, T. K M ; Nakamura, R. ; Baumjohann, W. ; Russell, C. T. ; Pollock, C. ; Lindqvist, P. A. ; Ergun, R. E. ; Burch, J. L. ; Torbert, R. B. ; Giles, B. L. / Evolution of a typical ion-scale magnetic flux rope caused by thermal pressure enhancement. In: Journal of Geophysical Research: Space Physics. 2017 ; Vol. 122, No. 2. pp. 2040-2050.
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