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Title: Sausage instabilities on top of kinking lengthening current-carrying magnetic flux tubes

Authors:
ORCiD logo [1];  [1]
  1. University of Washington, Seattle, Washington 98195-2400, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1361833
Grant/Contract Number:
SC0010340
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 5; Related Information: CHORUS Timestamp: 2018-02-14 23:46:17; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

von der Linden, Jens, and You, Setthivoine. Sausage instabilities on top of kinking lengthening current-carrying magnetic flux tubes. United States: N. p., 2017. Web. doi:10.1063/1.4981231.
von der Linden, Jens, & You, Setthivoine. Sausage instabilities on top of kinking lengthening current-carrying magnetic flux tubes. United States. doi:10.1063/1.4981231.
von der Linden, Jens, and You, Setthivoine. Mon . "Sausage instabilities on top of kinking lengthening current-carrying magnetic flux tubes". United States. doi:10.1063/1.4981231.
@article{osti_1361833,
title = {Sausage instabilities on top of kinking lengthening current-carrying magnetic flux tubes},
author = {von der Linden, Jens and You, Setthivoine},
abstractNote = {},
doi = {10.1063/1.4981231},
journal = {Physics of Plasmas},
number = 5,
volume = 24,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4981231

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  • The evolution of plasma in a current-carrying magnetic flux tube of variable cross section is investigated using a one-dimensional numerical simulation. The flux tube is narrow at the two ends and broad in the middle. The middle region of the flux tube is loaded with a hot plasma population, and the two ends have a much more dense gravitationally bound plasma. The result is that the number of particles per unit of flux tube length has a minimum near each end and a maximum in the middle where the flux tube has the largest cross section. A large potential difference,more » parallel to the magnetic field, is applied across the domain. The general result is that density minimum tends to deepen, primarily in the cathode end, and the entire potential drop becomes concentrated across the region of density minimum. The potential drop is maintained primarily by electron inertia. The evolution of the simulation shows some sensitivity to particle boundary conditions, but the simulations inevitably evolve into a final state with a nearly stationary double layer near the cathode end. The simulation results are at sufficient variance with observations that it appears unlikely that auroral electrons can be explained by a simple process of acceleration through a field-aligned potential drop.« less
  • The evolution of plasma in a current-carrying magnetic flux tube of variable cross section is investigated using a one-dimensional numerical simulation. The flux tube is narrow at the two ends and broad in the middle. The middle part of the flux tube is loaded with a hot, magnetically trapped population, and the two ends have a more dense, gravitationally bound population. A potential difference larger than the gravitational potential but less than the energy of the hot population is applied across the domain. The general result is that the potential change becomes distributed along the anode half of the domain,more » with negligible potential change on the cathode half. The potential is supported by the mirror force of magnetically trapped particles. The simulations show a steady depletion of plasma on the anode side of the flux tube. The current steadily decreases on a time scale of an ion transit time. The results may provide an explanation for the observed plasma depletions on auroral field lines carrying upward currents.« less
  • A localized perturbation of a magnetic flux tube produces wave trains that disperse as they propagate along the tube, where the extent of dispersion depends on the physical properties of the magnetic structure, on the length of the initial excitation, and on its nature (e.g., transverse or axisymmetric). In Oliver et al. we considered a transverse initial perturbation, whereas the temporal evolution of an axisymmetric one is examined here. In both papers we use a method based on Fourier integrals to solve the initial value problem. We find that the propagating wave train undergoes stronger attenuation for longer axisymmetric (ormore » shorter transverse) perturbations, while the internal to external density ratio has a smaller effect on the attenuation. Moreover, for parameter values typical of coronal loops axisymmetric (transverse) wave trains travel at a speed 0.75–1 (1.2) times the Alfvén speed of the magnetic tube. In both cases, the wave train passage at a fixed position of the magnetic tube gives rise to oscillations with periods of the order of seconds, with axisymmetric disturbances causing more oscillations than transverse ones. To test the detectability of propagating transverse or axisymmetric wave packets in magnetic tubes of the solar atmosphere (e.g., coronal loops, spicules, or prominence threads) a forward modeling of the perturbations must be carried out.« less