Relationships between the ion flow speed, magnetic flux transport rate, and other plasma sheet parameters

2005 ◽  
Vol 110 (A9) ◽  
Author(s):  
Richard L. Kaufmann ◽  
William R. Paterson ◽  
Louis A. Frank
Keyword(s):  
Magnetic Flux ◽  
Plasma Sheet ◽  
Flow Speed ◽  
Transport Rate ◽  
Flux Transport ◽  
Ion Flow

scholarly journals Average characteristics of the midtail plasma sheet in different dynamic regimes of the magnetosphere

2004 ◽  
Vol 22 (6) ◽  
pp. 2107-2113 ◽  
Author(s):  
N. P. Dmitrieva ◽  
V. A. Sergeev ◽  
M. A. Shukhtina
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Growth Phase ◽  
Plasma Sheet ◽  
Transfer Rate ◽  
Flux Transport ◽  
Data Set ◽  
Magnetospheric Convection ◽  
Flux Transfer ◽  
Night Flux

Abstract. We study average characteristics of plasma sheet convection in the middle tail during different magnetospheric states (Steady Magnetospheric Convection, SMC, and substorms) using simultaneous magnetotail (Geotail, 15-35 RE downtail) and solar wind (Wind spacecraft) observations during 3.5 years. (1) A large data set allowed us to obtain the average values of the plasma sheet magnetic flux transfer rate (Ey and directly compare it with the dayside transfer rate (Emod for different magnetospheric states. The results confirm the magnetic flux imbalance model suggested by Russell and McPherron (1973), namely: during SMC periods the day-to-night flux transport rate equals the global Earthward plasma sheet convection; during the substorm growth phase the plasma sheet convection is suppressed on the average by 40%, whereas during the substorm expansion phase it twice exceeds the day-to-night global flux transfer rate. (2) Different types of substorms were revealed. About 1/3 of all substorms considered displayed very weak growth in the tail lobe magnetic field before the onset. For these events the plasma sheet transport was found to be in a balance with the day-to-night flux transfer, as in the SMC events. However, the lobe magnetic field value in these cases was as large as that in the substorms with a classic growth phase just before the onset (both values exceed the average level of the lobe field during the SMC). Also, in both groups similar configurational changes (magnetic field stretching and plasma sheet thinning) were observed before the substorm onset. (3) Superimposed epoch analysis showed that the plasma sheet during the late substorm recovery phase has the characteristics similar to those found during SMC events, the SMC could be a natural magnetospheric state following the substorm.

The magnetic flux transport along the -Esw direction in the magnetotails on Mars and Venus

2020 ◽  
Author(s):  
Lihui Chai ◽  
James Slavin ◽  
Yong Wei ◽  
Weixing Wan ◽  
Charlie F. Bowers ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Flux ◽  
Pressure Gradient ◽  
Plasma Sheet ◽  
Magnetic Pressure ◽  
Mass Loading ◽  
Flux Transport ◽  
Loading Effect

<p>The induced magnetotails on Mars and Venus are considered to arise through the interplanetary magnetic field (IMF) draping around the planet and the solar wind deceleration due to the mass loading effect. They have very similar structures as that on Earth, two magnetic lobes of opposite radial magnetic fields and a plasma sheet in between. However, the orientation and geometry of the induced magnetotails are controlled by the IMF, not the planetary intrinsic magnetic field. In this study, we present another characteristic of the induced magnetotails on Mars and Venus with the observations of MAVEN and Venus Express. It is found that the magnetic flux in the induced magnetotails on Mars and Venus are inhomogeneous. There is more magnetic flux in the +E hemisphere than -E hemisphere. The magnetic flux is observed to transport gradually from the +E hemisphere to the -E hemisphere along the magnetotail. The magnetotail magnetic flux transport seems to be faster on Mars than that at Venus. Based on these observations, we suggest that the finite gyro-radius effect of the planetary ions that are picked up by the solar wind is responsible to the magnetic flux inhomogeneity and transport in the induced magnetotails. The role of the magnetic pressure gradient in the magnetotail will be discussed.</p>

scholarly journals Suprathermal electron acceleration during reconnection onset in the magnetotail

2011 ◽  
Vol 29 (10) ◽  
pp. 1917-1925 ◽  
Author(s):  
A. Vaivads ◽  
A. Retinò ◽  
Yu. V. Khotyaintsev ◽  
M. André
Keyword(s):  
Magnetic Flux ◽  
Electric Field ◽  
Plasma Sheet ◽  
Electron Acceleration ◽  
Flux Transport ◽  
Energetic Electrons ◽  
Flux Tubes ◽  
Suprathermal Electron ◽  
Suprathermal Electrons ◽  
Pile Up

Abstract. We study one event of reconnection onset associated to a small substorm on 27 September 2006 by using Cluster observations at inter-spacecraft separation of about 10 000 km. We focus on the acceleration of suprathermal electrons during different stages of reconnection. We show that several distinct stages of acceleration occur: (1) moderate acceleration during reconnection of pre-existing plasma sheet flux tubes, (2) stronger acceleration during reconnection of lobe flux tubes, (3) production of the most energetic electrons within dipolarization fronts (magnetic pile-up regions). The strongest acceleration is reached at the location of Bz maxima inside the magnetic pile-up region where the reconnection jet stops. Very strong localized dawn-dusk electric field are observed within the magnetic pile-up regions and are associated to most of the magnetic flux transport.

scholarly journals The storm time central plasma sheet

2002 ◽  
Vol 20 (11) ◽  
pp. 1737-1741 ◽  
Author(s):  
R. Schödel ◽  
K. Dierschke ◽  
W. Baumjohann ◽  
R. Nakamura ◽  
T. Mukai
Keyword(s):  
Magnetic Flux ◽  
Plasma Sheet ◽  
Neutral Line ◽  
Magnetic Storms ◽  
Main Phase ◽  
Plasma Convection ◽  
Flux Transport ◽  
Storm Main Phase ◽  
Central Plasma ◽  
Central Plasma Sheet

Abstract. The plasma sheet plays a key role during magnetic storms because it is the bottleneck through which large amounts of magnetic flux that have been eroded from the dayside magnetopause have to be returned to the dayside magnetosphere. Using about five years of Geotail data we studied the average properties of the near- and midtail central plasma sheet (CPS) in the 10–30 RE range during magnetic storms. The earthward flux transport rate is greatly enhanced during the storm main phase, but shows a significant earthward decrease. Hence, since the magnetic flux cannot be circulated at a sufficient rate, this leads to an average dipolarization of the central plasma sheet. An increase of the specific entropy of the CPS ion population by a factor of about two during the storm main phase provides evidence for nonadiabatic heating processes. The direction of flux transport during the main phase is consistent with the possible formation of a near-Earth neutral line beyond ~20 RE.Key words. Magnetospheric physics (plasma convection; plasma sheet; storms and substorms)

scholarly journals Fine structures and dynamics in auroral initial brightening at substorm onsets

2009 ◽  
Vol 27 (2) ◽  
pp. 623-630 ◽  
Author(s):  
K. Sakaguchi ◽  
K. Shiokawa ◽  
A. Ieda ◽  
R. Nomura ◽  
A. Nakajima ◽  
...  
Keyword(s):  
Plasma Sheet ◽  
Periodic Structures ◽  
Flow Speed ◽  
The Other ◽  
Physical Processes ◽  
Ion Flow ◽  
Scale Size ◽  
Fine Structures ◽  
Substorm Onsets ◽  
Fast Ion

Abstract. We show four auroral initial brightening events at substorm onsets focusing on fine structures and their longitudinal dynamics, which were observed by all-sky TV cameras (30-Hz sampling) on January 2008, in Canada. For two initial brightenings started in the field of views of the cameras, we found that they started at longitudinal segments with a size of less than ~30–60 km. One brightening expanded with wavy structures and the other expanded as a straight arc. Although the two events had different structures, both brightening auroras expanded with an average speed of ~20 km/s in the first 10 s, and ~10 km/s in the following 10 s. The other two events show that brightening auroras developed with periodic structures, with longitudinal wavelengths of ~100–200 km. Assuming that the brightening auroras are mapped to the physical processes occurring in the plasma sheet, we found that the scale size (30–60 km) and the expanding speed (20 km/s) of brightening auroras correspond to the order of ion gyro radii (~500–1400 km) and Alfvén speed or fast ion-flow speed (~400 km/s), respectively, in the plasma sheet.

Magnetic Flux Transport on the Sun

Science ◽  
1989 ◽  
Vol 245 (4919) ◽  
pp. 712-718 ◽  
Author(s):  
Y. -M. WANG ◽  
A. G. NASH ◽  
N. R. SHEELEY
Keyword(s):  
Magnetic Flux ◽  
The Sun ◽  
Flux Transport

scholarly journals Impact of nonlinear surface inflows into activity belts on the solar dynamo

2020 ◽  
Vol 10 ◽  
pp. 62
Author(s):  
Melinda Nagy ◽  
Alexandre Lemerle ◽  
Paul Charbonneau
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Activity Cycle ◽  
Surface Flux ◽  
Meridional Flow ◽  
Cycle Model ◽  
Flux Transport ◽  
Bona Fide ◽  
Nonlinear Surface ◽  
The Impact

We examine the impact of surface inflows into activity belts on the operation of solar cycle models based on the Babcock–Leighton mechanism of poloidal field regeneration. Towards this end we introduce in the solar cycle model of Lemerle & Charbonneau (2017. ApJ 834: 133) a magnetic flux-dependent variation of the surface meridional flow based on the axisymmetric inflow parameterization developped by Jiang et al. (2010. ApJ 717: 597). The inflow dependence on emerging magnetic flux thus introduces a bona fide nonlinear backreaction mechanism in the dynamo loop. For solar-like inflow speeds, our simulation results indicate a decrease of 10–20% in the strength of the global dipole building up at the end of an activity cycle, in agreement with earlier simulations based on linear surface flux transport models. Our simulations also indicate a significant stabilizing effect on cycle characteristics, in that individual cycle amplitudes in simulations including inflows show less scatter about their mean than in the absence of inflows. Our simulations also demonstrate an enhancement of cross-hemispheric coupling, leading to a significant decrease in hemispheric cycle amplitude asymmetries and temporal lag in hemispheric cycle onset. Analysis of temporally extended simulations also indicate that the presence of inflows increases the probability of cycle shutdown following an unfavorable sequence of emergence events. This results ultimately from the lower threshold nonlinearity built into our solar cycle model, and presumably operating in the sun as well.

Magnetic-flux transport by a convecting layer – topological, geometrical and compressible phenomena

1983 ◽  
Vol 132 ◽  
pp. 25-48 ◽  
Author(s):  
Wayne Arter
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Flux ◽  
Field Enhancement ◽  
Computer Code ◽  
Lower Half ◽  
Numerical Calculations ◽  
Flux Transport

Numerical calculations by Drobyshevski & Yuferev (1974) of the redistribution of magnetic flux by a Bénard layer with cells of square planform have been extended to higher values of electrical conductivity and to other velocity patterns, using a computer code developed for another purpose. Reconnection does not proceed as they supposed, but leads to overall field enhancement, and although the energy is greater at the bottom, there is as much unsigned flux in the upper half as in the lower half of the layer. However, compressible velocity patterns can concentrate flux at their bases.

Magnetic Flux Transport in the ISM through Turbulent Ambipolar Diffusion

2004 ◽  
pp. 45-51
Author(s):  
Fabian Heitsch ◽  
Ellen G. Zweibel ◽  
Adrianne D. Slyz ◽  
Julien E. G. Devriendt
Keyword(s):  
Magnetic Flux ◽  
Ambipolar Diffusion ◽  
Flux Transport
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