The role of magnetic flux tube deformation and magnetosheath plasma beta in the saturation of the Region 1 field-aligned current system

The basic model for the precipitation of trapped energetic particles from a magnetic flux tube is Kennel and Petschek’s (1966) model. Their model is symmetric, implying equal precipitation rates at the two feet of the flux tube. We have developed a model for precipitation in an asymmetric flux tube (Melrose and White 1979). Here we explore some of the consequences for the precipitation model of Melrose and Brown (1976) for solar hard X-ray bursts. In Melrose and Brown’s model roughly half the X-rays arise from precipitating electrons. With present instruments it is not possible to resolve the two feet of the flux tube. However, if the feet can be resolved, either directly by future X-ray telescopes, or indirectly through secondary optical, UV or radio observations, then, as we shall show, the additional information obtained could be used to derive information on processes in the magnetic trap.

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Ion velocity distributions within the LLBL and their possible implication to multiple reconnections

Annales Geophysicae ◽

10.5194/angeo-22-213-2004 ◽

2004 ◽

Vol 22 (1) ◽

pp. 213-236 ◽

Cited By ~ 4

Author(s):

O. L. Vaisberg ◽

L. A. Avanov ◽

T. E. Moore ◽

V. N. Smirnov

Keyword(s):

Magnetic Field ◽

Magnetic Flux ◽

Flux Tube ◽

Magnetic Flux Tube ◽

Flux Tubes ◽

Different Types ◽

Subsolar Point ◽

Magnetic Flux Tubes ◽

Ion Velocity ◽

Field Lines

Abstract. We analyze two LLBL crossings made by the Interball-Tail satellite under a southward or variable magnetosheath magnetic field: one crossing on the flank of the magnetosphere, and another one closer to the subsolar point. Three different types of ion velocity distributions within the LLBL are observed: (a) D-shaped distributions, (b) ion velocity distributions consisting of two counter-streaming components of magnetosheath-type, and (c) distributions with three components, one of which has nearly zero parallel velocity and two counter-streaming components. Only the (a) type fits to the single magnetic flux tube formed by reconnection between the magnetospheric and magnetosheath magnetic fields. We argue that two counter-streaming magnetosheath-like ion components observed by Interball within the LLBL cannot be explained by the reflection of the ions from the magnetic mirror deeper within the magnetosphere. Types (b) and (c) ion velocity distributions would form within spiral magnetic flux tubes consisting of a mixture of alternating segments originating from the magnetosheath and from magnetospheric plasma. The shapes of ion velocity distributions and their evolution with decreasing number density in the LLBL indicate that a significant part of the LLBL is located on magnetic field lines of long spiral flux tube islands at the magnetopause, as has been proposed and found to occur in magnetopause simulations. We consider these observations as evidence for multiple reconnection Χ-lines between magnetosheath and magnetospheric flux tubes. Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; solar wind-magnetosphere interactions)

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Generation of nonlinear magnetic flux tube wave energies in Procyon A

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3091 ◽

2019 ◽

Author(s):

D E Fawzy ◽

A T Saygac ◽

K Stȩpień

Keyword(s):

Magnetic Flux ◽

Acoustic Wave ◽

Flux Tube ◽

Convection Zone ◽

Frequency Factor ◽

Turbulent Energy ◽

Current Approach ◽

Magnetic Flux Tube ◽

Tube Wave ◽

Wave Modes

Abstract The aim of the current study is the computation of the magnetic flux tube wave energies and fluxes generated in the convection zone of Procyon A. This is a subgiant of spectral type F5 IV-V showing chromospheric and coronal activities. The mechanisms responsible for the generation of different wave modes include the interaction of the thin and vertically oriented magnetic flux tube embedded in magnetic-free regions with turbulence in the convection zone of Procyon A. We are considering longitudinal, transverse and acoustic wave modes. Turbulence in the convection zone is modeled by the extended Kolmogorov turbulent energy spectrum and the modified Gaussian frequency factor. Different magnetic flux tube models with different degrees of magnetic activities were considered. The current approach takes the nonlinear effects into consideration. The results show that there is enough wave energy in the three different forms to heat the outer layers of the star. The obtained acoustic wave energies are larger than those of the longitudinal tube wave energies compared to the solar case. This can be explained by the relatively low magnetic field strength. On the other side, our computations show the importance of the transverse wave energies compared to the energies carried by the longitudinal waves. The former waves carry energy several (between 2 and 14) times higher than the latter. The obtained wave energies are essential for constructing time-dependent model chromospheres and for the predictions of atmospheric oscillations to be compared e.g. with the data collected by the CoRoT and Kepler missions.

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Quasi-static evolution of a three-dimensional force-free magnetic flux tube or arcade

Physics of Magnetic Flux Ropes - Geophysical Monograph Series ◽

10.1029/gm058p0235 ◽

1990 ◽

pp. 235-239 ◽

Cited By ~ 1

Author(s):

J. J. Aly

Keyword(s):

Magnetic Flux ◽

Flux Tube ◽

Three Dimensional ◽

Magnetic Flux Tube

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Numerical simulations of the lower solar atmosphere heating by two-fluid nonlinear Alfvén waves

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937260 ◽

2020 ◽

Vol 639 ◽

pp. A45

Author(s):

B. Kuźma ◽

D. Wójcik ◽

K. Murawski ◽

D. Yuan ◽

S. Poedts

Keyword(s):

Magnetic Flux ◽

Numerical Simulations ◽

Solar Atmosphere ◽

Flux Tube ◽

Alfven Waves ◽

Alfven Wave ◽

Magnetic Flux Tube ◽

Alfvén Waves ◽

Two Fluid ◽

Lower Solar Atmosphere

Context. We present new insight into the long-standing problem of plasma heating in the lower solar atmosphere in terms of collisional dissipation caused by two-fluid Alfvén waves. Aims. Using numerical simulations, we study Alfvén wave propagation and dissipation in a magnetic flux tube and their heating effect. Methods. We set up 2.5-dimensional numerical simulations with a semi-empirical model of a stratified solar atmosphere and a force-free magnetic field mimicking a magnetic flux tube. We consider a partially ionized plasma consisting of ion + electron and neutral fluids, which are coupled by ion-neutral collisions. Results. We find that Alfvén waves, which are directly generated by a monochromatic driver at the bottom of the photosphere, experience strong damping. Low-amplitude waves do not thermalize sufficient wave energy to heat the solar atmospheric plasma. However, Alfvén waves with amplitudes greater than 0.1 km s−1 drive through ponderomotive force magneto-acoustic waves in higher atmospheric layers. These waves are damped by ion-neutral collisions, and the thermal energy released in this process leads to heating of the upper photosphere and the chromosphere. Conclusions. We infer that, as a result of ion-neutral collisions, the energy carried initially by Alfvén waves is thermalized in the upper photosphere and the chromosphere, and the corresponding heating rate is large enough to compensate radiative and thermal-conduction energy losses therein.

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