Head-on collision of dust magnetoacoustic solitary waves in magnetized plasmas

2013 ◽  
Vol 80 (2) ◽  
pp. 235-245 ◽  
Author(s):  
Shi-Sen Ruan ◽  
Zhong-Ming Li
Keyword(s):  
Solitary Waves ◽  
Magnetic Field Intensity ◽  
Acoustic Velocity ◽  
Number Density ◽  
Ion Temperature ◽  
Component Plasma ◽  
The Magnetic Field ◽  
Dust Surface ◽  
Dust Plasma ◽  
Alfven Velocity

AbstractThe head-on collision of dust magnetoacoustic solitary waves (DMASWs) is studied in magnetized electron–ion–dust plasma. The extended Poincaré–Lighthill–Kuo perturbation method is used to derive the Korteweg de Vries equations for DMASWs in this three-component plasma. The effects of the magnetic field intensity B0, the number of electrons residing on dust surface Zd, the ratio of electron to dust number density δ, the ratio of electron to ion temperature σ, and the ratio of dust acoustic velocity to dust Alfvén velocity β on the phase shift are investigated. It is found that these parameters can significantly influence the phase shifts of colliding DMASWs. The present investigation may be beneficial to understand the interaction between two DMASWs that may occur in plasma with dust impurities situations.

Head on collisions of magnetoacoustic solitary waves in magnetized pair ion–electron plasmas

2014 ◽  
Vol 92 (3) ◽  
pp. 225-229
Author(s):  
Shi-Sen Ruan ◽  
Majid Raissan ◽  
Shan Wu ◽  
Ze Cheng
Keyword(s):  
Magnetic Field ◽  
Solitary Waves ◽  
Magnetic Field Intensity ◽  
Negative Ions ◽  
Electron Plasma ◽  
Number Density ◽  
Electron Plasmas ◽  
Positive Ions ◽  
Component Plasma ◽  
The Magnetic Field

Head-on collisions of magnetoacoustic solitary waves (MASWs) are studied in magnetized pair ion–electron plasma. The extended Poincaré–Lighthill–Kuo perturbation method is used to derive the Korteweg – de Vries equations for MASWs in this three-component plasma. The effects of the magnetic field intensity B0, the ratio of negative ions to positive ions number density δ, and the plasma number density on the phase shift are investigated. It is found that these parameters can significantly influence the phase shifts of colliding MASWs. The present investigation should be useful for understanding the propagation and interaction between two MASWs that may occur in pair ion plasmas with electron impurities.

Statistical Differences of Magnetic Field Kinks Observed by PSP and WIND

2021 ◽  
Author(s):  
Chuanpeng Hou ◽  
Xingyu Zhu ◽  
Rui Zhuo ◽  
Jiansen He
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Radial Velocity ◽  
Slow Solar Wind ◽  
Number Density ◽  
Ion Temperature ◽  
Group I ◽  
Rotational Discontinuity ◽  
Background Magnetic Field ◽  
The Magnetic Field

<p>Parker Solar Probe’s (PSP) observations near the sun show the extensive presence of magnetic field kinks (switchback for large kinks) in the slow solar wind. These kinks are usually accompanied by the enhancement of radial solar wind velocity and ion temperature, increasing or decreasing of number density. The magnetic field kinks have also been observed by WIND and Ulysses to exist near and beyond 1 AU, respectively. In this study, we statistically analyze the property difference of magnetic field kinks observed by PSP and WIND. We obtain the following four points of results. (1) Inside the PSP-kinks, the radial velocity and protons’ temperature increase while density shows enhancement or descent. However, inside the WIND-kinks, besides the slight enhancement of radial velocity, the density and temperature show no obvious change compared with the outside plasma. (2) By employing the Walen-test of kinks, we find that, R components of some PSP-kinks but not all satisfy the rotational discontinuity (RD) features, while the three components of most WIND-kinks well match the RD features. (3) The correlation between magnetic field and velocity inside the PSP-kinks and WIND-kinks does not show significant differences. (4) Both the PSP-kinks and WIND-kinks can be divided into two groups based on the histograms of θ<sub>Bn</sub>, where B is the background magnetic field, and n is the normal direction of kink. The first group (group-I) has θ<sub>Bn</sub> concentrating around 20° for PSP-kinks and 30° for WIND-kinks, indicating that the satellites were crossing the same kinked interplanetary magnetic field (IMF) from the upstream to the downstream. The second group (group-II) has θ<sub>Bn</sub> concentrating around 90° for PSP-kinks and WIND-kinks, suggesting that the satellites were crossing an interface between the unkinked and kinked IMF regions. Our findings help better understanding the nature of kinks and provide the observational basis for testifying models about radial propagation and evolution of magnetic field kinks.</p>

scholarly journals Hydromagnetic dynamos in rotating spherical fluid shells in dependence on the Prandtl number, density stratification and electromagnetic boundary conditions

2014 ◽  
Vol 44 (4) ◽  
pp. 293-312 ◽  
Author(s):  
Tomáš Šoltis ◽  
Ján Šimkanin
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Magnetic Fields ◽  
Prandtl Number ◽  
Inner Core ◽  
Polar Regions ◽  
Number Density ◽  
Magnetic Diffusion ◽  
Spherical Fluid ◽  
The Magnetic Field

Abstract We present an investigation of dynamo in a simultaneous dependence on the non-uniform stratification, electrical conductivity of the inner core and the Prandtl number. Computations are performed using the MAG dynamo code. In all the investigated cases, the generated magnetic fields are dipolar. Our results show that the dynamos, especially magnetic field structures, are independent in our investigated cases on the electrical conductivity of the inner core. This is in agreement with results obtained in previous analyses. The influence of non-uniform stratification is for our parameters weak, which is understandable because most of the shell is unstably stratified, and the stably stratified region is only a thin layer near the CMB. The teleconvection is not observed in our study. However, the influence of the Prandtl number is strong. The generated magnetic fields do not become weak in the polar regions because the magnetic field inside the tangent cylinder is always regenerated due to the weak magnetic diffusion.

scholarly journals The influence of resistivity gradients on shock conditions for a Petschek reconnection geometry

2016 ◽  
Vol 34 (4) ◽  
pp. 421-425
Author(s):  
Christian Nabert ◽  
Karl-Heinz Glassmeier
Keyword(s):  
Magnetic Field ◽  
Necessary Conditions ◽  
The Other ◽  
Diffusion Region ◽  
Two Dimensional ◽  
Characteristic Velocity ◽  
Magnetohydrodynamic Equations ◽  
One Dimensional ◽  
The Magnetic Field ◽  
Alfven Velocity

Abstract. Shock waves can strongly influence magnetic reconnection as seen by the slow shocks attached to the diffusion region in Petschek reconnection. We derive necessary conditions for such shocks in a nonuniform resistive magnetohydrodynamic plasma and discuss them with respect to the slow shocks in Petschek reconnection. Expressions for the spatial variation of the velocity and the magnetic field are derived by rearranging terms of the resistive magnetohydrodynamic equations without solving them. These expressions contain removable singularities if the flow velocity of the plasma equals a certain characteristic velocity depending on the other flow quantities. Such a singularity can be related to the strong spatial variations across a shock. In contrast to the analysis of Rankine–Hugoniot relations, the investigation of these singularities allows us to take the finite resistivity into account. Starting from considering perpendicular shocks in a simplified one-dimensional geometry to introduce the approach, shock conditions for a more general two-dimensional situation are derived. Then the latter relations are limited to an incompressible plasma to consider the subcritical slow shocks of Petschek reconnection. A gradient of the resistivity significantly modifies the characteristic velocity of wave propagation. The corresponding relations show that a gradient of the resistivity can lower the characteristic Alfvén velocity to an effective Alfvén velocity. This can strongly impact the conditions for shocks in a Petschek reconnection geometry.

Effect of ion temperature on ion-acoustic solitary waves in a two-ion plasma

1988 ◽  
Vol 66 (6) ◽  
pp. 467-470 ◽  
Author(s):  
Sikha Bhattacharyya ◽  
R. K. Roychoudhury
Keyword(s):  
Mach Number ◽  
Analytical Solution ◽  
Solitary Waves ◽  
Experimental Result ◽  
Ion Temperature ◽  
Ion Plasma ◽  
Ion Acoustic Solitary Waves ◽  
Ion Acoustic ◽  
Cold Ions ◽  
Pseudopotential Approach

The effect of ion temperature on ion-acoustic solitary waves in the case of a two-ion plasma has been investigated using the pseudopotential approach of Sagdeev. An analytical solution for relatively small amplitudes has also been obtained. Our result has been compared, whenever possible, with the experimental result obtained by Nakamura. It is found that a finite ion temperature considerably modifies the restrictions on the Mach number obtained for cold ions.

scholarly journals Magnetotaxis as a Means for Nanofabrication

2014 ◽  
Vol 23 (01n02) ◽  
pp. 1450008
Author(s):  
Isaac Macwan ◽  
Zihe Zhao ◽  
Omar Sobh ◽  
Jinnque Rho ◽  
Ausif Mahmood ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Semiconductor Manufacturing ◽  
Magnetic Field Intensity ◽  
Magnetotactic Bacteria ◽  
Semiconductor Substrate ◽  
Field Lines ◽  
A Chain ◽  
Magnetospirillum Magneticum ◽  
The Magnetic Field

Magnetotactic bacteria (MTB), discovered in early 1970s contain single-domain crystals of magnetite ( Fe 3 O 4) called magnetosomes that tend to form a chain like structure from the proximal to the distal pole along the long axis of the cell. The ability of these bacteria to sense the magnetic field for displacement, also called magnetotaxis, arises from the magnetic dipole moment of this chain of magnetosomes. In aquatic habitats, these organisms sense the geomagnetic field and traverse the oxic-anoxic interface for optimal oxygen concentration along the field lines. Here we report an elegant use of MTB where magnetotaxis of Magnetospirillum magneticum (classified as AMB-1) could be utilized for controlled navigation over a semiconductor substrate for selective deposition. We examined 50mm long coils made out of 18AWG and 20AWG copper conductors having diameters of 5mm, 10mm and 20mm for magnetic field intensity and heat generation. Based on the COMSOL simulations and experimental data, it is recognized that a compound semiconductor manufacturing technology involving bacterial carriers and carbon-based materials such as graphene and carbon nanotubes would be a desirable choice in the future.

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