Quasi Periodic Oscillations in the Pre Phases of Recurrent Jets Highlighting Plasmoids in Current Sheet

2020 ◽  
Author(s):  
Reetika Joshi ◽  
Ramesh Chandra ◽  
Brigitte Schmieder ◽  
Guillaume Aulanier ◽  
Pooja Devi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
The Other ◽  
Active Region Noaa ◽  
The West ◽  
Periodic Oscillations ◽  
West Limb ◽  
Field Lines ◽  
Open Magnetic Field ◽  
Double Chamber

<p><strong>Solar jets observed at the limb are important to determine the location of reconnection sites in the corona. In this study, we investigate six recurrent hot and cool jets occurring in the active region NOAA 12644 as it is crossing the west limb on April 04, 2017. These jets are observed in all the UV/EUV filters of SDO/AIA and in cooler temperature formation lines in IRIS slit jaw images. The jets are initiated at the top of a double chamber vault with cool loops on one side and hot loops on the other side. The existence of such double chamber vaults suggests the presence of emerging flux with cool loops, the hot loops being the reconnected loops similarly as in the models of Moreno-</strong><strong>Insertis</strong><strong>et al. 2008, 2013 and Nóbrega-Siverio et al. 2016. In the preliminary phase of the main jets, </strong><strong>quasi periodic</strong><strong> intensity oscillations accompanied by smaller jets are detected in the bright current sheet between the vault and the preexisting magnetic field. Individual kernels and plasmoids are ejected in open field lines </strong><strong>along</strong><strong> the jets. Plasmoids may launch torsional Alfven waves and the kernels would be the result of the </strong><strong>untwist</strong><strong> of the plasmoids in open magnetic field as proposed in the model of Wyper et al. 2016.</strong></p>

scholarly journals Dynamical Galactic Halos

1993 ◽  
Vol 157 ◽  
pp. 415-419
Author(s):  
D. Breitschwerdt ◽  
H.J. Völk ◽  
V. Ptuskin ◽  
V. Zirakashvili
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
The Other ◽  
Galactic Rotation ◽  
Galactic Halos ◽  
Magnetic Forces ◽  
Dynamical Coupling ◽  
Field Lines ◽  
The Magnetic Field ◽  
Open Magnetic Field

It is argued that the description of the magnetic field in halos of galaxies should take into account its dynamical coupling to the other major components of the interstellar medium, namely thermal plasma and cosmic rays (CR's). It is then inevitable to have some loss of gas and CR's (galactic wind) provided that there exist some “open” magnetic field lines, facilitating their escape, and a sufficient level of self-generated waves which couple the particles to the gas. We discuss qualitatively the topology of the magnetic field in the halo and show how galactic rotation and magnetic forces can be included in such an outflow picture.

scholarly journals Equilibrium of the Return-Current Sheet and Structure of the Pulsar Magnetosphere

1992 ◽  
Vol 128 ◽  
pp. 112-113
Author(s):  
Yu. E. Lyubarskii
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Neutron Stars ◽  
Current Sheet ◽  
Equilibrium Condition ◽  
Pulsar Magnetosphere ◽  
Field Lines ◽  
Current Flows ◽  
Magnetic Poles ◽  
Open Magnetic Field

Pulsars are generally identified with rotating, magnetized neutron stars. According to Goldreich and Julian (1969), an induced electric field creates the electric current which flows out of the magnetic poles and fills the magnetosphere with plasma. The current flows along the open magnetic field lines and returns along the boundary between the closed and open parts of the magnetosphere (Scharlemann and Wagoner 1973). The boundary shape is determined by the equilibrium condition for the current sheet.

scholarly journals Magnetic Fields in the Lower Corona Associated with the Expanding Limb Burst On March 30th 1969 Inferred from the Microwave High-Resolution Observations

1971 ◽  
Vol 43 ◽  
pp. 413-416 ◽  
Author(s):  
Shinzo Énomé ◽  
Haruo Tanaka
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Magnetic Fields ◽  
The West ◽  
Lower Corona ◽  
Energetic Electrons ◽  
West Limb ◽  
Flare Region ◽  
Solar Microwave ◽  
Solar Microwave Burst

An expansion of the source of a great solar microwave burst was observed a little beyond the west limb on March 30, 1969. This expansion is interpreted in terms of diffusion of energetic electrons in a turbulent magnetic field in the flare region. The height of the source is estimated to have been 104 km.

Collisionless plasma transport mechanisms in stochastic open magnetic field lines in tokamaks

2021 ◽  
Author(s):  
Min-Gu Yoo ◽  
Weixing Wang ◽  
Edward A Startsev ◽  
Chenhao Ma ◽  
S Ethier ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Collisionless Plasma ◽  
Plasma Transport ◽  
Transport Mechanisms ◽  
Field Lines ◽  
Open Magnetic Field

Ballooning modes on open magnetic field lines

1999 ◽  
Vol 6 (3) ◽  
pp. 674-685 ◽  
Author(s):  
Eliezer Hameiri
Keyword(s):  
Magnetic Field ◽  
Field Lines ◽  
Open Magnetic Field

scholarly journals Spectroscopic Features in the EUV Emission of a M8 Flare Observed by SUMER

2001 ◽  
Vol 203 ◽  
pp. 260-263 ◽  
Author(s):  
W. Curdt ◽  
E. Landi ◽  
U. Feldman ◽  
D. Innes ◽  
B. Dwivedi ◽  
...  
Keyword(s):  
Active Region ◽  
Atomic Physics ◽  
Temporal Evolution ◽  
Diagnostic Techniques ◽  
Active Region Noaa ◽  
Plasma Diagnostic ◽  
The West ◽  
Euv Emission ◽  
West Limb ◽  
Spectral Scan

A flare of size M8 occurred while SUMER was recording a spectral scan above the active region NOAA 8537 at the west limb. We recorded spectra during the pre-flare phase, at flare onset, and during the decay phase of this main flare in a series of events. More than 60 flare lines were identified during this observation, which include Fe XVIII - Fe XXIII lines that provide evidence of 107 K plasmas. We also recorded lines from He-like ions, such as Ne IX, Na x, Mg XI, and Si XIII. Accurate wavelength measurements of such lines are of interest in basic atomic physics studies. Using plasma diagnostic techniques, we investigated the temporal evolution of the electron densities and temperatures during the event.

scholarly journals Nonlinear equilibrium structure of thin currents sheets: influence of electron pressure anisotropy

2004 ◽  
Vol 11 (5/6) ◽  
pp. 579-587 ◽  
Author(s):  
L. M. Zelenyi ◽  
H. V. Malova ◽  
V. Yu. Popov ◽  
D. Delcourt ◽  
A. S. Sharma
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Magnetic Energy ◽  
Plasma Pressure ◽  
Quasi Equilibrium ◽  
Electrostatic Effects ◽  
Current Sheets ◽  
Thin Current Sheet ◽  
Field Lines ◽  
The Magnetic Field

Abstract. Thin current sheets represent important and puzzling sites of magnetic energy storage and subsequent fast release. Such structures are observed in planetary magnetospheres, solar atmosphere and are expected to be widespread in nature. The thin current sheet structure resembles a collapsing MHD solution with a plane singularity. Being potential sites of effective energy accumulation, these structures have received a good deal of attention during the last decade, especially after the launch of the multiprobe CLUSTER mission which is capable of resolving their 3D features. Many theoretical models of thin current sheet dynamics, including the well-known current sheet bifurcation, have been developed recently. A self-consistent 1D analytical model of thin current sheets in which the tension of the magnetic field lines is balanced by the ion inertia rather than by the plasma pressure gradients was developed earlier. The influence of the anisotropic electron population and of the corresponding electrostatic field that acts to restore quasi-neutrality of the plasma is taken into account. It is assumed that the electron motion is fluid-like in the direction perpendicular to the magnetic field and fast enough to support quasi-equilibrium Boltzmann distribution along the field lines. Electrostatic effects lead to an interesting feature of the current density profile inside the current sheet, i.e. a narrow sharp peak of electron current in the very center of the sheet due to fast curvature drift of the particles in this region. The corresponding magnetic field profile becomes much steeper near the neutral plane although the total cross-tail current is in all cases dominated by the ion contribution. The dependence of electrostatic effects on the ion to electron temperature ratio, the curvature of the magnetic field lines, and the average electron magnetic moment is also analyzed. The implications of these effects on the fine structure of thin current sheets and their potential impact on substorm dynamics are presented.

scholarly journals Transition Between Type I and Type III Bursts in Closed or Open Magnetic Field Lines

1980 ◽  
Vol 86 ◽  
pp. 363-368
Author(s):  
Monique G. Aubier
Keyword(s):  
Magnetic Field ◽  
Velocity Component ◽  
Low Frequency ◽  
Critical Value ◽  
Type I ◽  
Accelerated Electrons ◽  
Type Iii ◽  
Field Lines ◽  
Parallel Momentum ◽  
Open Magnetic Field

When studying the propagation of accelerated electrons outwards in the corona, we have shown that the perpendicular momentum of the electrons remaining after the type I process is transformed into parallel momentum during the propagation along the decreasing magnetic field, and that type III emission can occur when the parallel velocity component reaches a critical value. With this model we explain in particular the low frequency cut-off of type I emission, the characteristics of the type III bursts near their starting frequency and the transition between type III- and type I-like decameter emission observed in few cases.

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