WAVES IN A RAREFIED IONIZED GAS PROPAGATED TRANSVERSE TO AN EXTERNAL MAGNETIC FIELD

1961 ◽  
Vol 39 (7) ◽  
pp. 1044-1057 ◽  
Author(s):  
Tomiya Watanabe
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Sound Waves ◽  
Ionized Gas ◽  
Frequency Limit ◽  
Electrons And Ions ◽  
Hydromagnetic Waves ◽  
Perturbed Magnetic Field

Waves being propagated in a rarefied and fully ionized gas and transverse to an external magnetic field have been studied, particularly hydromagnetic waves. Three modes of waves, in which the perturbed magnetic field is parallel to the external magnetic field, are found to be propagated. In a high-frequency limit, they tend to electromagnetic waves, electron sound waves, and ion sound waves. In the condition that the Alfvén velocity is greater than the ion sound velocity but smaller than the light velocity, the last mode tends to a hydromagnetic wave in the low-frequency limit. The other two modes of waves can be propagated only at frequencies higher than the critical frequencies, both of which almost equal the electron plasma frequency. The condition that hydromagnetic waves should be attenuated severely due to collisions between electrons and ions has been derived.

Helicity waves propagating in a plasma

1991 ◽  
Vol 45 (3) ◽  
pp. 481-488 ◽  
Author(s):  
Z. Yoshida
Keyword(s):  
Magnetic Field ◽  
Faraday Effect ◽  
Low Frequency ◽  
Plasma Waves ◽  
Frequency Limit ◽  
High Frequencies ◽  
Transverse Modes ◽  
Longitudinal Part ◽  
The Waves ◽  
Perturbed Magnetic Field

There exist plasma waves that transport helicity although they do not propagate electromagnetic energy. The dispersion relations of such helicity waves are studied. The electric field of the waves is parallel to the perturbed magnetic field, and both are perpendicular to the perturbed current. In cross-field propagation, a helicity wave is decomposed into two transverse modes with different polarizations and a longitudinal part. The helicity waves are principally Alfvénic in the low-frequency limit. At high frequencies, the Faraday effect comes into the polarization.

On the upper frequency limit of whistler mode waves observed by low-altitude spacecraft

2020 ◽  
Author(s):  
Frantisek Nemec ◽  
Ondřej Santolík ◽  
Michel Parrot
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Realistic Model ◽  
Wave Intensity ◽  
Frequency Limit ◽  
Whistler Mode ◽  
The Earth ◽  
Whistler Mode Waves ◽  
Low Altitude

<p>Frequency-latitude plots of electromagnetic wave intensity in the very low frequency range (VLF, up to about 20 kHz) observed by the low altitude DEMETER spacecraft are analyzed. Apart from electromagnetic waves generated by plasma instabilities in the magnetosphere, a significant portion of the detected wave intensity comes from ground-based lightning activity and VLF military transmitters. These whistler mode waves are observed not only close to source locations, but also close to their geomagnetically conjugated points. There appears to be an upper frequency limit of such emissions, where the wave intensity substantially decreases. Its frequency roughly corresponds to half of the equatorial electron cyclotron frequency at a respective magnetic field line, suggesting a relation to wave ducting in ducts with enhanced density. However, it seems to exhibit a non-negligible longitudinal dependence and it is different during the day than during the night. We use a realistic model of the Earth’s magnetic field to explain the observed variations. We interpret the observations in terms of ducted/unducted wave propagation, and we compare the wave intensities in the source hemisphere with those measured in the hemisphere geomagnetically conjugated.</p>

Metamaterials from Amorphous Ferromagnetic Microwires: Interaction between Microwires

2009 ◽  
Vol 152-153 ◽  
pp. 357-360 ◽  
Author(s):  
Andrei V. Ivanov ◽  
A.N. Shalygin ◽  
V.Yu. Galkin ◽  
A.V. Vedyayev ◽  
V.A. Ivanov
Keyword(s):  
Magnetic Field ◽  
Refractive Index ◽  
Optical Properties ◽  
External Magnetic Field ◽  
Electromagnetic Waves ◽  
Negative Refractive Index ◽  
Magnus Effect ◽  
Amorphous Ferromagnet ◽  
Wide Scale ◽  
Optical Magnus Effect

For inhomogeneous mediums the оptical Magnus effect has been derived. The metamaterials fabricated from amorphous ferromagnet Co-Fe-Cr-B-Si microwires are shown to exhibit a negative refractive index for electromagnetic waves over wide scale of GHz frequencies. Optical properties and optical Magnus effect of such metamaterials are tunable by an external magnetic field.

Filamentation and collapse of Langmuir waves in a weak magnetic field

1982 ◽  
Vol 28 (1) ◽  
pp. 19-36 ◽  
Author(s):  
P. Rolland ◽  
S. G. Tagare
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Small Angle ◽  
Nonlinear Interaction ◽  
High Frequency ◽  
Weak Magnetic Field ◽  
Low Frequency ◽  
Langmuir Waves ◽  
The Magnetic Field

The filamentation and collapse of Langmuir waves in a weak magnetic field are analysed in two particular cases of low-frequency acoustic perturbations: (i) adiabatic perturbations which correspond to subsonic collapse, and (ii) nonadiabatic perturbations which correspond to supersonic collapse. Here the existence of Langmuir filaments and Langmuir collapse in a weak magnetic field are due to nonlinear interaction of high-frequency Langmuir waves (which make small angle with the external magnetic field) with low-frequency acoustic perturbations along the magnetic field.

Influence of dispersion on the modulational instability of a whistler wave

1989 ◽  
Vol 41 (2) ◽  
pp. 289-300 ◽  
Author(s):  
V. I. Karpman ◽  
A. G. Shagalov
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Growth Rates ◽  
Cyclotron Frequency ◽  
Modulational Instability ◽  
Low Frequency ◽  
Whistler Wave ◽  
Long Wave ◽  
Frequency Modulations ◽  
Magnetic Sound

The modulational instability of a whistler wave propagating along an external magnetic field is investigated, taking into account the dispersion of the low-frequency modulations. The dispersive effects are significant if the modulation frequencies Ω are comparable to or greater than the ion cyclotron frequency ωci. It is shown that in this case there are four unstable branches: the long-wave modulational instability and three others with much larger growth rates. At Ω≪ωci the latter correspond to fast magnetic sound, Alfvén and slow magnetic sound branches.

Propagation of electromagnetic waves in a warm plasma-filled cylindrical waveguide in the presence of an external magnetic field

1983 ◽  
Vol 29 (3) ◽  
pp. 383-392 ◽  
Author(s):  
Sanjay Kumar Ghosh ◽  
S. P. Pal
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Electromagnetic Waves ◽  
Transverse Magnetic ◽  
Cylindrical Waveguide ◽  
Small Magnetic Field ◽  
Warm Plasma ◽  
Plasma Theory ◽  
The Waves ◽  
Constant External Magnetic Field

The propagation of electromagnetic waves in a plasma-filled cylindrical waveguide in the presence of a constant external magnetic field is investigated using warm plasma theory. It is found that the waves cannot be separated into transverse magnetic and transverse electric modes; only hybrid modes are propagated. Dispersion relations are derived for zero, finite and infinite magnetic fields. Frequency shifts for the wave propagation in the case of a small magnetic field are calculated.

Sign in / Sign up

Export Citation Format

Share Document