scholarly journals Study of magnetohydrodynamic effects for the richtmyer-meshkov instability

2019 ◽  
Author(s):  
◽  
Wolfgang Justice Black
Keyword(s):  
Magnetic Field ◽  
Mach Number ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Plasma Jet ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Mhd Waves ◽  
Field Orientation ◽  
Magnetic Fi Eld

This work presents experimental and computational studies of the Richtmyer-Meshkov (RM) instability with Magnetohydrodynamic (MHD) effects. The experimental work does not consider the instability or its growth, but rather developes an atmospheric plasma jet for use in future magnetohydrodynamic experiments. The operating conditions of the torch are explored to optimize the ionized length of the plasma jet by varying the voltage-current characteristics and the gas low rates. Probe, spectral, and visual diagnostics are also developed in an effort to characterize the plasma. The probe diagnostics were unsuccessful but discussions are included to help improve the technique. The visual Mie-Scattering like technique is able to capture qualitative images of the plasma flow field and are ready for use in future hydrodynamic experiments where the qualitative growth is of interest. Simulations utilized the hydrocode FLAG, developed at Los Alamos National Laboratory, are performed on a 2D shock cylinder plasma-air interface where MHD effects work to remove vorticity from the interface and suppress RM growth. To study this magnetic field orientation, magnetic field strength, and incident Mach number are all varied in this study. It was found that the orientation of the magnetic fi eld relative to the shock wave direction causes different morphology and can effect the amount of observable RM suppression. Similarly, increasing the magnetic field strength reduces the effects of the baroclinic vorticity, responsible for RM growth, by generating strong MHD waves which carry the vorticity away from the interface quicker. Increasing the Mach number can also cause varying qualitative effects, with greater Mach numbers showing greater interfacial compression. But comparing the MHD RM to the RM instability at a single Mach number still shows suppresion of the instability. Finally a 3D cylindrical interface is simulated using the hydrocode ARES. These simulations compare the cylindrical Richtmyer-Meshkov to two cases of the MHD-RM instability; one with a parallel and one with a perpendicular magnetic fi eld of 500 Guass. As per literature, the magnetic cases exhibit suppression through decreased enstrophy, vorticity, and mixedness with respect to time in addition to the clear morphological differences.

scholarly journals Asymmetries in the Earth's dayside magnetosheath: results from global hybrid-Vlasov simulations

2020 ◽  
Author(s):  
Lucile Turc ◽  
Vertti Tarvus ◽  
Andrew Dimmock ◽  
Markus Battarbee ◽  
Urs Ganse ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Mach Number ◽  
Field Strength ◽  
Flow Velocity ◽  
Magnetic Field Strength ◽  
Bow Shock ◽  
Wide Range ◽  
The Magnetic Field ◽  
The Imf

<p>The magnetosheath is the region bounded by the bow shock and the magnetopause which is home to shocked solar wind plasma. At the interface between the solar wind and the magnetosphere, the magnetosheath plays a key role in the coupling between these two media. Previous works have revealed pronounced dawn-dusk asymmetries in the magnetosheath properties, with for example the magnetic field strength and flow velocity being larger on the dusk side, while the plasma is denser, hotter and more turbulent on the dawn side. The dependence of these asymmetries on the upstream parameters remains however largely unknown. One of the main sources of these asymmetries is the bow shock configuration, which is typically quasi-parallel on the dawn side and quasi-perpendicular on the dusk side of the terrestrial magnetosheath because of the Parker-spiral orientation of the interplanetary magnetic field (IMF) at Earth. Most of these previous studies rely on collections of spacecraft measurements associated with a wide range of upstream conditions that have been processed to obtain the average values of the magnetosheath parameters. In this work, we use a different approach and quantify the magnetosheath asymmetries in global hybrid-Vlasov simulations performed with the Vlasiator model. We concentrate on three parameters: the magnetic field strength, the plasma density and the flow velocity. We find that the Vlasiator model reproduces accurately the polarity of the asymmetries, but that their level tends to be higher than in spacecraft measurements, probably due to the different processing methods. We investigate how the asymmetries change when the IMF becomes more radial and when the Alfvén Mach number decreases. When the IMF makes a 30° angle with the Sun-Earth line instead of 45°, we find a stronger magnetic field asymmetry and a larger variability of the magnetosheath density. In contrast, a lower Alfvén Mach number leads to a decrease of the magnetic field asymmetry level and of the variability of the magnetosheath density and velocity, likely due to weaker foreshock processes.</p>

Compressible models of fast steady-state magnetic reconnection

1989 ◽  
Vol 42 (1) ◽  
pp. 111-132 ◽  
Author(s):  
M. Jardine ◽  
E. R. Priest
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Mach Number ◽  
Field Strength ◽  
Magnetic Reconnection ◽  
Magnetic Field Strength ◽  
Maximum Rate ◽  
Diffusion Region ◽  
Reconnection Process ◽  
Main Effects

We investigate the effects of compressibility on magnetic reconnection, using as a basis the incompressible models of Priest & Forbes and Jardine & Priest. Our results show that compressibility modifies the reconnection process, without changing its essential character. In the region of inflowing plasma, compressibility tends to increase the convergence or divergence of the flow. Also, for regimes with a compression in the inflow the maximum rate of reconnection is increased, while for regimes with an expansion in the inflow the magnetic Mach number at the entrance to the diffusion region is increased. In the region of outflowing plasma the main effects of compressibility are to produce faster and narrower outflow jets, with a lower magnetic field strength.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

2D analysis of magnetic field strength in GO SiFe steel sheets

1998 ◽  
Vol 08 (PR2) ◽  
pp. Pr2-579-Pr2-582 ◽  
Author(s):  
S. Tumanski ◽  
M. Stabrowski
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Steel Sheets

MAGNETIC FIELD, PRESSURE AND TEMPERATURE DEPENDENT OPTICAL PROPERTIES IN A GaAs 9.0 P 1.0 QUANTUM DOT

2014 ◽  
Vol 6 (2) ◽  
pp. 1178-1190
Author(s):  
A. JOHN PETER ◽  
Ada Vinolin
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Quantum Dot ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Photon Energy ◽  
Nonlinear Optical ◽  
Binding Energies ◽  
Nonlinear Optical Properties ◽  
Optical Rectification

Simultaneous effects of magnetic field, pressure and temperature on the exciton binding energies are found in a 9.0 1.0 6.0 4.0 GaAs P / GaAs P quantum dot. Numerical calculations are carried out taking into consideration of spatial confinement effect. The cylindrical system is taken in the present problem with the strain effects. The electronic properties and the optical properties are found with the combined effects of magnetic field strength, hydrostatic pressure and temperature values. The exciton binding energies and the nonlinear optical properties are carried out taking into consideration of geometrical confinement and the external perturbations.Compact density approach is employed to obtain the nonlinear optical properties. The optical rectification coefficient is obtained with the photon energy in the presence of pressure, temperature and external magnetic field strength. Pressure and temperature dependence on nonlinear optical susceptibilities of generation of second and third order harmonics as a function of incident photon energy are brought out in the influence of magnetic field strength. The result shows that the electronic and nonlinear optical properties are significantly modified by the applications of external perturbations in a 9.0 1.0 6.0 4.0 GaAs P / GaAs P quantum dot.

Magnetic field strength dependence of chemical shift artifacts

1988 ◽  
Vol 12 (2) ◽  
pp. 89-96 ◽  
Author(s):  
R. Lufkin ◽  
M. Anselmo ◽  
J. Crues ◽  
W. Smoker ◽  
W. Hanafee
Keyword(s):  
Magnetic Field ◽  
Chemical Shift ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Strength Dependence
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