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  • 1
    Electronic Resource
    Electronic Resource
    On fast magnetosonic coronal pulsations (1995)
    Springer
    Solar physics 159 (1995), S. 399-402 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The linear properties of the fast magnetosonic modes of a coronal loop modelled as a smooth density inhomogeneity in a uniform magnetic field are compared with the case of a step function slab. It is shown that the group velocityC gof the modes, important in determining the structure of impulsively excited wave packets, possesses a minimum for a wide class of profile including the slab, with the exception of the Epstein profile for which the minimum inC gmoves out to infinity. Results for the simple step profile are thus of wider validity, and likely to be applicable to coronal loops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686541
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  • 2
    Electronic Resource
    Electronic Resource
    Latent Heating of Coronal Loops (1997)
    Springer
    Solar physics 175 (1997), S. 107-121 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The theory of weakly nonlinear slow magnetosonic waves in thin flux tubes is developed. A Korteweg–de Vries equation is derived for slow body waves. The analysis of solitary and periodic solutions shows that the nonlinear waves produce running narrowings of the tube. The similarity of the shallow-water theory and the thin-flux-tube approximation helps to outline the peaking and breaking of the nonlinear slow body waves. It appears that the running narrowing of the tube works as the de Laval nozzle in generating a cool supersonic jet and a subsequent shock that heats the plasma. The presented theory of nonlinear slow body waves suggests a mechanism of coronal loop heating, which meets many of the observational constraints.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004909603871
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  • 3
    Electronic Resource
    Electronic Resource
    Alfvén Wave Phase Mixing as a Source of Fast Magnetosonic Waves (1997)
    Springer
    Solar physics 175 (1997), S. 93-105 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The nonlinear excitation of fast magnetosonic waves by phase mixing Alfvén waves in a cold plasma with a smooth inhomogeneity of density across a uniform magnetic field is considered. If initially fast waves are absent from the system, then nonlinearity leads to their excitation by transversal gradients in the Alfvén wave. The efficiency of the nonlinear Alfvén–fast magnetosonic wave coupling is strongly increased by the inhomogeneity of the medium. The fast waves, permanently generated by Alfvén wave phase mixing, are refracted from the region with transversal gradients of the Alfvén speed. This nonlinear process suggests a mechanism of indirect plasma heating by phase mixing through the excitation of obliquely propagating fast waves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004965725929
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  • 4
    Electronic Resource
    Electronic Resource
    Resonant interactions of modes in coronal magnetic flux tubes (1995)
    Springer
    Solar physics 160 (1995), S. 289-302 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nonlinear resonant interactions of different kinds of fast magnetosonic (FMS) waves trapped in the inhomogeneity of a low-β plasma density, stretched along a magnetic field (as, for example, in coronal loops) are investigated. A set of equations describing the amplitudes of interactive modes is derived for an arbitrary density profile. The quantitative characteristics of such interactions are found. The decay instability of the wave with highest frequency is possible in the system. If amplitudes of interactive modes have close values, the long-period temporal and spatial oscillations are in the system. For a quantitative illustration, the parabolic approximation of the transverse density profile has been chosen. Dispersion relations of FMS waves trapped in a low-β plasma slab with a parabolic transverse density profile are found. The transverse structure of the waves in this case can be expressed through Hermitian polynomials. The interaction of kink and sausage waves is investigated. The sausage wave, with a sufficiently large amplitude, may be unstable with respect to the decay into two kink waves, in particular. The spatial scale of a standing wave structure and the time spectrum of radiation are formed due to the nonlinear interactions of loop modes which contain information about the parameters of the plasma slab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00732809
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  • 5
    Electronic Resource
    Electronic Resource
    Waves in cosmic magnetic structures taking into account the anisotropic plasma pressure (1995)
    Springer
    Solar physics 158 (1995), S. 29-41 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper provides an analysis of magneto-sonic eigenwaves travelling in magnetic plasma structures based on the Chew-Goldberger-Low approximation, for which the plasma kinetic pressure is different along and across the magnetic field. The anisotropy does not lead to the emergence of new modes. The dependence of phase velocities of the waves, trapped by a single magnetic surface, on the pressure anisotropy is investigated. For a magnetic slab with field-free surroundings, the dispersion relations for the eigenwaves are obtained. The pressure anisotropy may change dispersion relations of such modes significantly. In particular, backward waves are possible in the case of strong anisotropy. The dependences of the thresholds for the mirror and hose instabilities on the system parameters are obtained. In particular, hose and mirror instabilities of such waves are absent for some wave number regions. The results are used to obtain the eigenwave characteristics in coronal loops and chromospheric flux tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00680833
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  • 6
    Electronic Resource
    Electronic Resource
    Nonlinearly selected frequencies in coronal loops (1996)
    Springer
    Solar physics 168 (1996), S. 273-277 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A nonlinear process for the resonant generation of low-frequency fast magnetosonic kink waves in coronal loops is discussed. The efficiency of the process is strongly enhanced due to the existence of a nonlinearly selected frequency produced by a constant frequency difference in the dispersion curves in the short wavelength limit. The kink wave with the selected frequency interacts with high-frequency kink and sausage waves. The efficiency of such interaction does not require coherence in the interactive waves. In a loop of width 2 × 103 km, field strength 50 G and number density 5 × 1015 m−3, the nonlinearly selected frequency is of order 46 mHz (period 21.8 s), but this may range through 11 mHz to 184 mHz (periods 86.5 s to 5.4 s) for typical coronal conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148055
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  • 7
    Electronic Resource
    Electronic Resource
    OSCILLATIONS IN PROMINENCE FINE-STRUCTURES (1997)
    Springer
    Solar physics 173 (1997), S. 81-101 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Oscillatory spectra of solar quiescent prominences highlight the importance of incorporating the effect of prominence fine-structure in the theory of prominence oscillations. We determine the magnetohydrodynamic modes of oscillation of an elementary, zero-β model of a prominence fibril, arguing that the fast body kink modes, namely, the string and the internal magnetic Love modes, produce the observed short periodicities in prominence fine-structures. Estimates for the periods of these modes are presented: the modes are subject to testing in future high-resolution observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004917710650
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  • 8
    Electronic Resource
    Electronic Resource
    A Manifestation of Negative Energy Waves in the Solar Atmosphere (1997)
    Springer
    Solar physics 176 (1997), S. 285-297 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Magnetosonic modes of magnetic structures of the solar atmosphere in the presence of inhomogeneous steady flows are considered. It is shown that, when the speed of the steady flow exceeds the phase speed of one of the modes, the mode has negative energy, and can be subject to an over-stability due to the negative energy wave instabilities. It is shown that registered steady flows in the solar atmosphere, with speeds below the threshold of the Kelvin–Helmholtz instability, can provide the existence of the magnetosonic negative energy wave phenomena. In particular, in isolated photospheric magnetic flux tubes, there are kink surface modes with negative energy, produced by the external granulation downflows. Dissipative instability of these modes due to finite thermal conductivity and explosive instability due to nonlinear coupling of these modes with Alfvén waves are discussed. For coronal loops, it is found that only very high-speed flows (〉300 km s-1) can produce negative energy slow body modes. In solar wind flow structures, both slow and fast body modes have negative energy and are unstable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004977928351
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  • 9
    Electronic Resource
    Electronic Resource
    Magnetosonic waves in structured atmospheres with steady flows (1995)
    Springer
    Solar physics 159 (1995), S. 213-228 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The magnetosonic modes of magnetic plasma structures in the solar atmosphere are considered taking into account steady flows of plasma in the internal and external media and using a slab geometry. The investigation brings nearer the theory of magnetosonic waveguides, in such structures as coronal loops and photospheric flux tubes, to realistic conditions of the solar atmosphere. The general dispersion relation for the magnetosonic modes of a magnetic slab in magnetic surroundings is derived, allowing for field-aligned steady flows in either region. It is shown that flows change both qualitatively and quantitatively the characteristics of magnetosonic modes. The flow may lead to the appearance of a new type of trapped mode, namelybackward waves. These waves are the usual slab modes propagating in the direction opposite to the internal flow, but advected with the flow. The disappearance of some modes due to the flow is also demonstrated. The results are applied to coronal and photospheric magnetic structures. In coronal loops, the appearance of backward slow body waves or the disappearance of slow body waves, depending upon the direction of propagation, is possible if the flow speed exceeds the internal sound speed (≈ 300 km s−1). In photospheric tubes, the disappearance of fast surface and slow body waves may be caused by an external downdraught of about 3 km s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686530
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  • 10
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    Phenomenon of Alfvénic Vortex Shedding (2010)
    American Physical Society
    Details
    Publication Date: 2010-07-30
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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