scholarly journals Scaling laws for magnetic reconnection, set by regulation of the electron pressure anisotropy to the firehose threshold

2015 ◽  
Vol 42 (24) ◽  
pp. 10,549-10,556 ◽  
Author(s):  
O. Ohia ◽  
J. Egedal ◽  
V. S. Lukin ◽  
W. Daughton ◽  
A. Le
Keyword(s):  
Magnetic Reconnection ◽  
Scaling Laws ◽  
Electron Pressure ◽  
Pressure Anisotropy

Model of electron pressure anisotropy in the electron diffusion region of collisionless magnetic reconnection

2010 ◽  
Vol 17 (12) ◽  
pp. 122102 ◽  
Author(s):  
A. Divin ◽  
S. Markidis ◽  
G. Lapenta ◽  
V. S. Semenov ◽  
N. V. Erkaev ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Diffusion Region ◽  
Electron Diffusion ◽  
Electron Pressure ◽  
Pressure Anisotropy

scholarly journals Hybrid simulations of magnetic reconnection with kinetic ions and fluid electron pressure anisotropy

2016 ◽  
Vol 23 (3) ◽  
pp. 032114 ◽  
Author(s):  
A. Le ◽  
W. Daughton ◽  
H. Karimabadi ◽  
J. Egedal
Keyword(s):  
Magnetic Reconnection ◽  
Electron Pressure ◽  
Pressure Anisotropy ◽  
Hybrid Simulations

Effects of electron pressure anisotropy on current sheet configuration

2016 ◽  
Vol 23 (9) ◽  
pp. 092901 ◽  
Author(s):  
A. V. Artemyev ◽  
I. Y. Vasko ◽  
V. Angelopoulos ◽  
A. Runov
Keyword(s):  
Current Sheet ◽  
Electron Pressure ◽  
Pressure Anisotropy

scholarly journals Onset of magnetic reconnection in a collisionless, high- plasma

2019 ◽  
Vol 85 (1) ◽  
Author(s):  
Andrew Alt ◽  
Matthew W. Kunz
Keyword(s):  
Magnetic Reconnection ◽  
Collisionless Plasma ◽  
High Plasma ◽  
Tearing Modes ◽  
Associated Production ◽  
Pressure Anisotropy ◽  
Low Threshold ◽  
Collisionless Reconnection ◽  
Field Lines ◽  
The Impact

In a magnetized, collisionless plasma, the magnetic moment of the constituent particles is an adiabatic invariant. An increase in the magnetic-field strength in such a plasma thus leads to an increase in the thermal pressure perpendicular to the field lines. Above a$\unicode[STIX]{x1D6FD}$-dependent threshold (where$\unicode[STIX]{x1D6FD}$is the ratio of thermal to magnetic pressure), this pressure anisotropy drives the mirror instability, producing strong distortions in the field lines on ion-Larmor scales. The impact of this instability on magnetic reconnection is investigated using a simple analytical model for the formation of a current sheet (CS) and the associated production of pressure anisotropy. The difficulty in maintaining an isotropic, Maxwellian particle distribution during the formation and subsequent thinning of a CS in a collisionless plasma, coupled with the low threshold for the mirror instability in a high-$\unicode[STIX]{x1D6FD}$plasma, imply that the geometry of reconnecting magnetic fields can differ radically from the standard Harris-sheet profile often used in simulations of collisionless reconnection. As a result, depending on the rate of CS formation and the initial CS thickness, tearing modes whose growth rates and wavenumbers are boosted by this difference may disrupt the mirror-infested CS before standard tearing modes can develop. A quantitative theory is developed to illustrate this process, which may find application in the tearing-mediated disruption of kinetic magnetorotational ‘channel’ modes.

scholarly journals Experimental Verification of the Role of Electron Pressure in Fast Magnetic Reconnection with a Guide Field

2017 ◽  
Vol 118 (12) ◽  
Author(s):  
W. Fox ◽  
F. Sciortino ◽  
A. v. Stechow ◽  
J. Jara-Almonte ◽  
J. Yoo ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Experimental Verification ◽  
Electron Pressure ◽  
Guide Field

Helium line emission: its relation to atmospheric structure

1980 ◽  
Vol 297 (1433) ◽  
pp. 541-554 ◽  
Keyword(s):  
Temperature Gradient ◽  
Transition Region ◽  
Scaling Laws ◽  
Coronal Holes ◽  
Emission Measure ◽  
Line Emission ◽  
Electron Pressure ◽  
Steep Temperature Gradient ◽  
Region Temperature ◽  
Higher Temperature

A brief review is given of observations of the resonance lines of He I and He II and their interpretation. As discussed in a previous paper, the helium lines are anomalously strong in the quiet Sun when compared with other transition region lines. The enhancement can be brought about by the transient excitation of the lines by electrons of higher temperature than that which determines the ion population. The variation in the intensity of the helium lines relative to those of other transition region lines appears to be related to variations in the temperature gradient between different parts of the atmosphere. To relate the degree of enhancement to other observable parameters, such as electron pressure and absolute line intensities, and thus to the structure of the atmosphere, a method for analysing the emission measure distribution previously developed in the context of the quiet atmosphere and active region loops is applied also to coronal holes. It is proposed that the non-thermal ion motions observed in the transition region can provide the required mechanism for transporting the helium ions across the steep temperature gradient. By making a simple model, an expression is developed which relates the helium enhancement to the non-thermal motions, the transition region temperature gradient and the electron pressure. The scaling laws implied can be tested against further observations when they become available.

scholarly journals Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

2016 ◽  
Vol 461 (2) ◽  
pp. 2162-2173 ◽  
Author(s):  
S. V. Komarov ◽  
I. I. Khabibullin ◽  
E. M. Churazov ◽  
A. A. Schekochihin
Keyword(s):  
Electron Pressure ◽  
Pressure Anisotropy ◽  
Bremsstrahlung Emission ◽  
Thermal Bremsstrahlung

On the Gradient of the Electron Pressure in Anti-Parallel Magnetic Reconnection

2015 ◽  
Vol 32 (4) ◽  
pp. 045201
Author(s):  
Huan-Yu Wang ◽  
Can Huang ◽  
Quan-Ming Lu ◽  
Shui Wang
Keyword(s):  
Magnetic Reconnection ◽  
Electron Pressure

scholarly journals Numerical study of non-gyrotropic electron pressure effects in collisionless magnetic reconnection

2021 ◽  
Vol 28 (7) ◽  
pp. 072108
Author(s):  
A. Sladkov ◽  
R. Smets ◽  
N. Aunai ◽  
A. Korzhimanov
Keyword(s):  
Magnetic Reconnection ◽  
Numerical Study ◽  
Pressure Effects ◽  
Electron Pressure
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