Lower-hybrid drift and Buneman instabilities in current sheets with guide field

2008 ◽  
Vol 15 (11) ◽  
pp. 112105 ◽  
Author(s):  
P. H. Yoon ◽  
A. T. Y. Lui
2008 ◽  
Vol 15 (7) ◽  
pp. 072101 ◽  
Author(s):  
P. H. Yoon ◽  
A. T. Y. Lui
Keyword(s):  

1985 ◽  
Vol 107 ◽  
pp. 315-328
Author(s):  
J. D. Huba

A review of several microinstabilities that have been suggested as possible anomalous transport mechanisms in current sheets is presented. The specific application is to a ‘field reversed plasma’ which is relevant to the so-called ‘diffusion region’ of a reconnection process. The linear and nonlinear properties of the modes are discussed, and each mode is assessed as to its importance in reconnection processes based upon these properties. It is concluded that the two most relevant instabilities are the ion acoustic instability and the lower-hybrid-drift instability. However, each instability has limitations as far as reconnection is concerned, and more research is needed in this area.


2014 ◽  
Vol 21 (5) ◽  
pp. 052104 ◽  
Author(s):  
K. Tummel ◽  
L. Chen ◽  
Z. Wang ◽  
X. Y. Wang ◽  
Y. Lin

2014 ◽  
Vol 32 (10) ◽  
pp. 1349-1360 ◽  
Author(s):  
I. Y. Vasko ◽  
A. V. Artemyev ◽  
A. A. Petrukovich ◽  
H. V. Malova

Abstract. We study the kinetic structure of intense ion-scale current sheets with strong electron currents and the guide field having a bell-shape profile. We consider four crossings of the Earth magnetotail current sheet by the Cluster mission in 2003. The thickness of these current sheets is about the ion inertial length and significantly smaller than the characteristic ion gyroradius. We analyze the asymmetry of the electron velocity distribution functions and show that the electron current is provided by the small electron subpopulation interpreted as an electron beam or two counter-streaming electron beams. The beam (counter-streaming beams) has a bulk velocity of the order of the electron thermal velocity and a density (difference of beam densities) of about 1–5% of the plasma density. To describe the observed current sheets we develop a kinetic model with particle beams. The model predicts different thickness of the current sheet for different types of current carriers (one electron beam or two counter-streaming electron beams). The observed ion-scale current sheets can be explained assuming that the current is carried by one electron beam and a co-streaming ion beam. Although the ion beam does not carry a significant current, this beam is required to balance the electron current perpendicular to the current sheet neutral plane. The developed model explains the dominance of the electron current and the ion scales of the current sheets.


2020 ◽  
Vol 47 (21) ◽  
Author(s):  
Jongsoo Yoo ◽  
Jeong‐Young Ji ◽  
M. V. Ambat ◽  
Shan Wang ◽  
Hantao Ji ◽  
...  
Keyword(s):  

2020 ◽  
Author(s):  
Binbin Tang ◽  
Wenya Li ◽  
Daniel Graham ◽  
Chi Wang ◽  
Yuri Khotyaintsev ◽  
...  

<div>Lower hybrid waves are investigated at the magnetosheath separatrix region in asymmetric guide-field reconnection at Earth’s magnetopause by using MMS observations. These waves are found in a limited region, depending on the density gradient across the separatrix, and they are driven by the lower hybrid drift instability. Properties of these waves are presented: (1) the waves propagate towards the x-line due to the out-of-plane magnetic field, consistent with the electron drift direction; (2) the wave potential is about 20% of the electron temperature. These drift waves effectively produce cross-field particle diffusion, enabling the entry of magnetosheath electrons into the exhaust region.</div>


2021 ◽  
Vol 28 (7) ◽  
pp. 072102
Author(s):  
Shan Wang ◽  
Li-Jen Chen ◽  
Jonathan Ng ◽  
Naoki Bessho ◽  
Michael Hesse
Keyword(s):  

Author(s):  
K-J. Hwang ◽  
K. Dokgo ◽  
E. Choi ◽  
J. L. Burch ◽  
D. G. Sibeck ◽  
...  

On May 5, 2017 MMS observed a bifurcated current sheet at the boundary of Kelvin-Helmholtz vortices (KHVs) developed on the dawnside tailward magnetopause. We use the event to enhance our understanding of the formation and structure of asymmetric current sheets in the presence of density asymmetry, flow shear, and guide field, which have been rarely studied. The entire current layer comprises three separate current sheets, each corresponding to magnetosphere-side sunward separatrix region, central near-X-line region, and magnetosheath-side tailward separatrix region. Two off-center structures are identified as slow-mode discontinuities. All three current sheets have a thickness of ∼0.2 ion inertial length, demonstrating the sub-ion-scale current layer, where electrons mainly carry the current. We find that both the diamagnetic and electron anisotropy currents substantially support the bifurcated currents in the presence of density asymmetry and weak velocity shear. The combined effects of strong guide field, low density asymmetry, and weak flow shear appear to lead to asymmetries in the streamlines and the current-layer structure of the quadrupolar reconnection geometry. We also investigate intense electrostatics waves observed on the magnetosheath side of the KHV boundary. These waves may pre-heat a magnetosheath population that is to participate into the reconnection process, leading to two-step energization of the magnetosheath plasma entering into the magnetosphere via KHV-driven reconnection.


2021 ◽  
Vol 923 (1) ◽  
pp. L13
Author(s):  
Alexander Chernoglazov ◽  
Bart Ripperda ◽  
Alexander Philippov

Abstract We present high-resolution 2D and 3D simulations of magnetized decaying turbulence in relativistic, resistive magnetohydrodynamics. The simulations show dynamic formation of large-scale intermittent long-lived current sheets being disrupted into plasmoid chains by the tearing instability. These current sheets are locations of enhanced magnetic-field dissipation and heating of the plasma. We find magnetic energy spectra ∝k −3/2, together with strongly pronounced dynamic alignment of Elsässer fields and of velocity and magnetic fields, for strong guide-field turbulence, whereas we retrieve spectra ∝k −5/3 for the case of a weak guide-field.


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