Edge condition and "intrinsic loss" in uniaxial plasma

1968 ◽  
Vol 46 (2) ◽  
pp. 111-120 ◽  
Author(s):  
S. W. Lee ◽  
R. Mittra

The electromagnetic field behavior near the edge of a conducting wedge in contact with a uniaxial plasma is investigated. The static magnetic field in the plasma is assumed to be perpendicular to the edge. Explicit expressions are obtained for the eigenvalue t which governs the edge behavior. The nonresonance case is treated first and the results are extended subsequently to the resonance case via analytic continuation of the functions involved, using a three-sheeted Riemann surface. The behavior of t is found to be distinctly different in the resonance case from either the isotropic or the nonresonance case in that singularities at the edge now occur for a certain range of the external angle of the conducting wedge, less than π. It is also found that "intrinsic losses" may occur for certain parameters in a purely lossless resonance plasma. However, the degenerate surface wave discussed by earlier workers does not accompany the intrinsic-loss phenomenon as it does for a parallel orientation of the d-c. magnetic field investigated by the above workers. Consequently, it is no longer possible to explain the intrinsic loss in terms of energy transported by the degenerate surface wave. A possible resolution of this difficulty is suggested for an ideally lossless medium via the derivation of a mathematical solution which does not display any intrinsic losses, and hence, satisfies the energy condition in such a system. The slightly lossy case is examined in detail and it is shown that in the presence of some loss in the medium, however slight, large energy losses are expected to occur in the neighborhood of the edge. Nevertheless, these losses are explainable and should not be regarded as "intrinsic".

1998 ◽  
Vol 11 (1) ◽  
pp. 376-376
Author(s):  
S.G. Moiseenko

Results of 2D numerical simulation of the magneto rotational mechanism of a supernova explosion are presented. Simulation has been done for the real equations of state and neutrino energy losses have been taken into account. Simulation has been done on the basis of an Implicit Lagrangian scheme on atriangular grid with grid reconstructuring. It is shown that, due to differential rotation of the star, a toroidal component of the magnetic field appears and grows with time. Rotational momentum transfers outwards as the toroidal component grows with time. With the evolution of the process, part of the envelope of the star is ejected. The amounts of the thrown-off mass and energy are estimated. The results of the simulation could be used as a possible explanation for the supernova explosion picture.


1967 ◽  
Vol 3 (3) ◽  
pp. 546-551
Author(s):  
S. Ohteru ◽  
H. Kobayashi ◽  
I. Nashiyama

1987 ◽  
Vol 40 (6) ◽  
pp. 755 ◽  
Author(s):  
AZ Kazbegi ◽  
GZ Machabeli ◽  
G Melikidze

The generation of radio waves in the plasma of the pulsar magnetosphere is considered taking into account the inhomogeneity of the dipole magnetic field. It is shown that the growth rate of the instability of the electromagnetic waves calculated in the non-resonance case turns out to be of the order of 1/ TO (where TO is the time of plasma escape from the light cylinder). However, the generation of electromagnetic waves from a new type Cherenkov resonance is possible, occurring when the particles have transverse velocities caused by the drift due to the inhomogeneity of the magnetic field. Estimates show that the development of this type of instability is possible only for pulsars with ages which exceed 104 yr. We make an attempt to explain some peculiarities of 'typical' pulsar emission on the basis of the model developed.


2021 ◽  
Vol 2103 (1) ◽  
pp. 012233
Author(s):  
I V Volodin ◽  
A A Alabuzhev

Abstract In the present paper a dynamics of a thin ferrofluid film under the vertical vibration in a static magnetic field is examined. The vibrational amplitude is assumed to be greater than film thickness so that vibrational force is greater than magnetic and gravitational forces. The pulsating part and the averaged part of the hydrodynamics fields are obtained. The solution of pulsating part for the traveling surface wave is found. The equation for the averaged surface profile is found.


Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1306
Author(s):  
Kirill Bronnikov ◽  
Vladimir Krechet ◽  
Vadim Oshurko

We find a family of exact solutions to the Einstein–Maxwell equations for rotating cylindrically symmetric distributions of a perfect fluid with the equation of state p=wρ (|w|<1), carrying a circular electric current in the angular direction. This current creates a magnetic field along the z axis. Some of the solutions describe geometries resembling that of Melvin’s static magnetic universe and contain a regular symmetry axis, while some others (in the case w>0) describe traversable wormhole geometries which do not contain a symmetry axis. Unlike Melvin’s solution, those with rotation and a magnetic field cannot be vacuum and require a current. The wormhole solutions admit matching with flat-space regions on both sides of the throat, thus forming a cylindrical wormhole configuration potentially visible for distant observers residing in flat or weakly curved parts of space. The thin shells, located at junctions between the inner (wormhole) and outer (flat) regions, consist of matter satisfying the Weak Energy Condition under a proper choice of the free parameters of the model, which thus forms new examples of phantom-free wormhole models in general relativity. In the limit w→1, the magnetic field tends to zero, and the wormhole model tends to the one obtained previously, where the source of gravity is stiff matter with the equation of state p=ρ.


1993 ◽  
Vol 157 ◽  
pp. 413-414
Author(s):  
Martin Pohl

We reexamine the minimum energy method to determine the magnetic field strength in spiral galaxies from the cosmic ray standpoint of view. It is shown that for example in M51 the estimated field strength is about a factor of 2 lower than obtained with the standard method. As a by-product the corresponding γ-ray flux from the galaxies can be calculated, which will allow further improvement of the method provided reliable γ-ray spectra are at hand.


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