The double-gradient magnetic instability: Stabilizing effect of the guide field

Тип публикации: статья из журнала

Год издания: 2015

Идентификатор DOI: 10.1063/1.4905706

Ключевые слова: Balloons, Magnetic fields, 2-D numerical simulation, Approximated solutions, Grad-Shafranov equations, Magnetic configuration, Magnetic field components, Magnetic field line, Magnetic instability, Radius of curvature, Magnetism

Аннотация: The role of the dawn-dusk magnetic field component in stabilizing of the magnetotail flapping oscillations is investigated in the double-gradient model framework (Erkaev et al., Phys. Rev. Lett. 99, 235003 (2007)), extended for the magnetotail-like configurations with non-zero guide field By. Contribution of the guide field is examined both analytically and by means of linearized 2-dimensional (2D) and non-linear 3-dimensional (3D) MHD modeling. All three approaches demonstrate the same properties of the instability: stabilization of current sheet oscillations for short wavelength modes, appearing of the typical (fastest growing) wavelength lambda(peak) of the order of the current sheet width, decrease of the peak growth rate with increasing B-y value, and total decay of the mode for B-y similar to 0: 5 in the lobe magnetic field units. Analytical solution and 2D numerical simulations claim also the shift of lambda(peak) toward the longer wavelengths with increasing guide field. This result is barely visible in 3D simulations. It may be accounted for the specific background magnetic configuration, the pattern of tail-like equilibrium provided by approximated solution of the conventional Grad-Shafranov equation. The configuration demonstrates drastically changing radius of curvature of magnetic field lines, R-c. This, in turn, favors the "double-gradient" mode (lambda > R-c) in one part of the sheet and classical "ballooning" instability (lambda

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Издание

Журнал: PHYSICS OF PLASMAS

Выпуск журнала: Vol. 22, Is. 1

ISSN журнала: 1070664X

Место издания: MELVILLE

Издатель: AMER INST PHYSICS

Авторы

  • Korovinskiy D.B. (Saint Petersburg State University)
  • Biernat H.K. (Institute of Physics, University of Graz)
  • Divin A.V. (Swedish Institute of Space Physics)
  • Semenov V.S. (Saint Petersburg State University)
  • Ivanova V.V. (Saint Petersburg State University)
  • Ivanov I.B. (Theoretical Physics Division, Petersburg Nuclear Physics Institute)
  • Erkaev N.V. (Siberian Federal University)
  • Artemyev A.V. (Space Research Institute RAS)
  • Lapenta G. (Centrum voor Plasma-Astrofysica, Departement Wiskunde, Katholieke Universiteit Leuven)
  • Markidis S. (PDC Center for High Performance Computing, KTH Royal Institute of Technology)

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