scholarly journals Examining the Magnetic Signal Due To Gravity and Plasma Pressure Gradient Current With the TIE-GCM

2017 ◽  
Vol 122 (12) ◽  
pp. 12,486-12,504 ◽  
Author(s):  
A. Maute ◽  
A. D. Richmond
Keyword(s):  
Pressure Gradient ◽  
Plasma Pressure ◽  
Magnetic Signal

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 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.

Influence of plasma pressure gradient on melt layer macroscopic erosion of metal targets in disruption simulation experiments

2003 ◽  
Vol 313-316 ◽  
pp. 685-689 ◽  
Author(s):  
V TERESHIN ◽  
I GARKUSHA ◽  
A BANDURA ◽  
O BYRKA ◽  
V CHEBOTAREV ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Plasma Pressure ◽  
Simulation Experiments

scholarly journals Azimuthal plasma pressure gradient in quiet time plasma sheet

2009 ◽  
Vol 36 (14) ◽  
Author(s):  
X. Xing ◽  
L. R. Lyons ◽  
V. Angelopoulos ◽  
D. Larson ◽  
J. McFadden ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Plasma Sheet ◽  
Plasma Pressure ◽  
Quiet Time

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

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

An Attack on the Contamination Problem in the Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 368-368
Author(s):  
J. J. Kelsch ◽  
A. Holtz
Keyword(s):  
Electron Microscope ◽  
Pressure Gradient ◽  
Ionization Potential ◽  
Simple Solution ◽  
Specimen Surface ◽  
Contamination Rate ◽  
Local Pressure ◽  
High Ionization ◽  
Hydrocarbon Molecules ◽  
Contamination Problem

A simple solution to the serious problem of specimen contamination in the electron microscope is presented. This is accomplished by the introduction of clean helium into the vacuum exactly at the specimen position. The local pressure gradient thus established inhibits the migration of hydrocarbon molecules to the specimen surface. The high ionization potential of He permits the use of relatively large volumes of the gas, without interfering with gun stability. The contamination rate is reduced on metal samples by a factor of 10.

Hydration Chamber for Jeolco 200 Kv Microscope

1970 ◽  
Vol 28 ◽  
pp. 542-543
Author(s):  
V. R. Matricardi ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscope ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Pressure Gradient ◽  
Room Temperature ◽  
List Type ◽  
Type Number ◽  
Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

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