scholarly journals Multiple inverted-V structures and hot plasma pressure gradient mechanism of plasma stratification

1998 ◽  
Vol 103 (A5) ◽  
pp. 9317-9332 ◽  
Author(s):  
E. E. Antonova ◽  
M. V. Stepanova ◽  
M. V. Teltzov ◽  
B. A. Tverskoy
Keyword(s):  
Pressure Gradient ◽  
Plasma Pressure ◽  
Hot Plasma

Effect of poloidal equilibrium flow and pressure gradient on the m/n = 2/1 tearing mode

2022 ◽  
Author(s):  
Yue Ming ◽  
Deng Zhou ◽  
Jinfang Wang
Keyword(s):  
Pressure Gradient ◽  
Stability Index ◽  
Plasma Pressure ◽  
Mode Number ◽  
Pressure Perturbation ◽  
Equilibrium Flow ◽  
Tearing Mode ◽  
Mode Instability ◽  
Mode Stability ◽  
Adverse Influence

Abstract The effect of equilibrium poloidal flow and pressure gradient on the m/n = 2/1 (m is the poloidal mode number and n is the toroidal mode number) tearing mode instability for tokamak plasmas is investigated. Based on the condition of ≠0 ( is plasma pressure), the radial part of motion equation is derived and approximately solved for large poloidal mode numbers (m). By solving partial differential equation (Whittaker equation) containing second order singularity, the tearing mode stability index Δ′ is obtained. It is shown that, the effect of equilibrium poloidal flow and pressure gradient has the adverse effect on the tearing mode instability when the pressure gradient is nonzero. The poloidal equilibrium flow with pressure perturbation partially reduces the stability of the classical tearing mode. But the larger pressure gradient in a certain poloidal flow velocity range can abate the adverse influence of equilibrium poloidal flow and pressure gradient. The numerical results do also indicate that the derivative of pressure gradient has a significant influence on the determination of instability region of the poloidal flow with pressure perturbation.

scholarly journals Energetic electron enhancements under the radiation belt (<i>L</i> < 1.2) during a non-storm interval on 1 August 2008

2019 ◽  
Vol 37 (6) ◽  
pp. 1223-1241 ◽  
Author(s):  
Alla V. Suvorova ◽  
Alexei V. Dmitriev ◽  
Vladimir A. Parkhomov
Keyword(s):  
Electric Fields ◽  
Radiation Belt ◽  
Energetic Electron ◽  
Plasma Pressure ◽  
Plasma Jets ◽  
Unusual Event ◽  
Hot Plasma ◽  
Low Latitudes ◽  
Pressure Pulses ◽  
Dawn Sector

Abstract. An unusual event of deep injections of >30 keV electrons from the radiation belt to low L shells (L<1.2) in the midnight–dawn sector was found from NOAA/POES observations during quiet geomagnetic conditions on 1 August 2008. Using THEMIS observations in front of the bow shock, we found transient foreshock conditions and interplanetary magnetic field (IMF) discontinuities passing the subsolar region at that time. These conditions resulted in generation of plasma pressure pulses and fast plasma jets observed by THEMIS, respectively, in the foreshock and magnetosheath. Signatures of interactions of pressure pulses and jets with the magnetopause were found in THEMIS and GOES measurements in the dayside magnetosphere and ground magnetogram records from INTERMAGNET. The jets produce penetration of hot magnetosheath plasma into the dayside magnetosphere, as was observed by the THEMIS probes after approaching the magnetopause. High-latitude precipitations of the hot plasma were observed by NOAA/POES satellites on the dayside. The precipitations preceded the >30 keV electron injections at low latitudes. We propose a scenario of possible association between the phenomena observed. However, the scenario cannot be firmly supported because of the lack of experimental data on electric fields at the heights of electron injections. This should be a subject of future experiments.

scholarly journals A rotating and magnetized three-dimensional hot plasma equilibrium in a gravitational field

2015 ◽  
Vol 81 (3) ◽  
Author(s):  
Peter J. Catto ◽  
Sergei I. Krasheninnikov
Keyword(s):  
Magnetic Field ◽  
Gravitational Field ◽  
Equatorial Plane ◽  
Three Dimensional ◽  
Rotation Frequency ◽  
High Plasma ◽  
Plasma Pressure ◽  
Hot Plasma ◽  
Field Lines ◽  
Open Magnetic Field

A rotating and magnetized three-dimensional axisymmetric equilibrium for hot plasma confined by a gravitational field is found. The plasma density and current can exhibit strong equatorial plane localization, resulting in disk equilibria with open magnetic field lines. The associated equatorial plane pinching results in magnetic field flaring, implying a strong gravitational squeezing of the plasma carrying ambient magnetic field lines toward the gravitational source. At high plasma pressure, the magnetic field becomes strongly radial outside the disk. The model predicts the rotation frequency bound, the condition for a plasma disk, and the requirement for strong magnetic field flaring.

Ganymede’s magnetic footprint mapping: Modeling and HST observations

2020 ◽  
Author(s):  
Tatphicha Promfu ◽  
Suwicha Wannawichian ◽  
Jonathan Nichols ◽  
John Clarke
Keyword(s):  
Magnetic Field ◽  
Hubble Space Telescope ◽  
Volcanic Eruptions ◽  
Plasma Pressure ◽  
Magnetic Field Mapping ◽  
Hot Plasma ◽  
Pressure Anisotropy ◽  
Magnetic Field Model ◽  
Field Lines ◽  
The Magnetic Field

&lt;p&gt;In this work, the locations of observed Ganymede&amp;#8217;s magnetic footprint were compared with the locations predicted by the magnetic field model under different plasma conditions. The shifts of Ganymede's magnetic footprint locations from average footpath given by Grodent et al. (2008) were analyzed. The average path is created from about 1000 images taken by instruments onboarded Hubble Space Telescope (HST). The position shifts indicate the variation of magnetic field line mapping from Ganymede to Jupiter&amp;#8217;s ionosphere. The two sets of data from HST were analyzed to obtain the locations of Ganymede&amp;#8217;s magnetic footprint in 2007 and 2016. For both sets of data, at longitude ranging approximately from 170&amp;#176; to 180&amp;#176;, we found that the locations were significantly shifted in poleward direction between 0.5&amp;#176; to 2&amp;#176; from the average footpath. Different from data in May 2007, the Ganymede&amp;#8217;s magnetic footprint locations in May 2016 at longitude about 160&amp;#176; could possibly locate in equatorward direction. At orbital distance of Ganymede about 15 R&lt;sub&gt;J&lt;/sub&gt;, in Jupiter&amp;#8217;s middle magnetosphere, there is strong influence of plasma, whose major source is Io&amp;#8217;s volcanic eruptions. Thus, the variations of plasma resulting in the stretching of magnetic field lines affect the magnetic field mapping from Ganymede to ionosphere. Furthermore, based on the magnetodisc model, the hot plasma pressure anisotropy&amp;#160;strongly influences the stretching of the field lines and the mapped locations of Ganymede&amp;#8217;s footprint in ionosphere to be shifted in either poleward or equatorward directions. In this study, we detected both poleward and equatorward shifts in different observations, whose connection with the plasma environment in the middle magnetosphere awaits for further study.&lt;/p&gt;

Axisymmetric global gravitational equilibrium for magnetized, rotating hot plasma

2015 ◽  
Vol 81 (6) ◽  
Author(s):  
Peter J. Catto ◽  
Istvan Pusztai ◽  
Sergei I. Krasheninnikov
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Plasma Density ◽  
Equatorial Plane ◽  
Magnetic Energy ◽  
Plasma Pressure ◽  
Gravitational Energy ◽  
Equilibrium Solutions ◽  
Poloidal Magnetic Field ◽  
Hot Plasma

We present analytic solutions for three-dimensional magnetized axisymmetric equilibria confining rotating hot plasma in a gravitational field. Our up–down symmetric solution to the full Grad–Shafranov equation can exhibit equatorial plane localization of the plasma density and current, resulting in disk equilibria for the plasma density. For very weak magnetic fields and high plasma pressure, we find strongly rotating thin plasma disk gravitational equilibria that satisfy strict Keplerian motion provided the gravitational energy is much larger than the plasma pressure, which must be large compared to the magnetic energy of the poloidal magnetic field. When the rotational energy exceeds the gravitational energy and it is larger than the plasma pressure, diffuse disk equilibrium solutions continue to exist provided the poloidal magnetic energy remains small. For stronger magnetic fields and lower plasma pressure and rotation, we can also find gravitational equilibria with strong localization to the equatorial plane. However, a toroidal magnetic field is almost always necessary to numerically verify these equilibria are valid solutions in the presence of gravity for the cases considered in Catto & Krasheninnikov (J. Plasma Phys., vol. 81, 2015, 105810301). In all cases both analytic and numerical results are presented.

scholarly journals Analysis of Deformation and Erosion during CME Evolution

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 314
Author(s):  
Skralan Hosteaux ◽  
Emmanuel Chané ◽  
Stefaan Poedts
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Flux ◽  
Pressure Gradient ◽  
Magnetic Cloud ◽  
Plasma Pressure ◽  
Closed Field ◽  
Background Wind ◽  
Field Lines ◽  
Density Results

Magnetised coronal mass ejections (CMEs) are quite substantially deformed during their journey form the Sun to the Earth. Moreover, the interaction of their internal magnetic field with the magnetic field of the ambient solar wind can cause deflection and erosion of their mass and magnetic flux. We here analyse axisymmetric (2.5D) MHD simulations of normal and inverse CME, i.e., with the opposite or same polarity as the background solar wind, and attempt to quantify the erosion and the different forces that operate on the CMEs during their evolution. By analysing the forces, it was found that an increase of the background wind density results in a stronger plasma pressure gradient in the sheath that decelerates the magnetic cloud more. This in turn leads to an increase of the magnetic pressure gradient between the centre of the magnetic cloud and the separatrix, causing a further deceleration. Regardless of polarity, the current sheet that forms in our model between the rear of the CME and the closed field lines of the helmet streamer, results in magnetic field lines being stripped from the magnetic cloud. It is also found that slow normal CMEs experience the same amount of erosion, regardless of the background wind density. Moreover, as the initial velocity increases, so does the influence of the wind density on the erosion. We found that increasing the CME speed leads to a higher overall erosion due to stronger magnetic reconnection. For inverse CMEs, field lines are not stripped away but added to the magnetic cloud, leading to about twice as much magnetic flux at 1 AU than normal CMEs with the same initial flux.

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