On the structure of azimuthally small-scale ULF oscillations of hot space plasma in a curved magnetic field. Modes with continuous spectrum

Cheremnykh, O. K.; Klimushkin, D. Yu.; Kostarev, Danila

doi:10.3103/s088459131405002x

Cited by 18 publications

(12 citation statements)

References 40 publications

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“…The instability can develop only on the slow-mode branch. This is in accordance with the results of earlier papers (Mazur, Fedorov, and Pilipenko, 2012;Kozlov et al, 2014;Cheremnykh, Klimushkin, and Kostarev, 2014). However, the instability threshold depends on the symmetry properties of the Alfvén mode.…”

Section: General Properties Of the Solutions For Symmetric And Antisysupporting

confidence: 92%

“…The opposite case, k r → 0, corresponds to the cut-offs (e.g. Cheremnykh, Klimushkin, and Kostarev, 2014). The cut-off surfaces are determined by the equation…”

Section: Alfvén Mode Eigenfunctions Symmetric With Respect To ϕ = π/2mentioning

confidence: 99%

“…The shear of the magnetic field is neglected. Mathematically, this work is based on the set of equations for the coupled Alfvén and slow magnetoacoustic modes derived in Klimushkin (1997Klimushkin ( , 1998 and Cheremnykh and Danilova (2011), and the formalism developed for the study of the spatial structure of the unstable modes in the terrestrial magnetosphere (Klimushkin, 2006;Klimushkin and Chen, 2006;Mazur, Fedorov, and Pilipenko, 2013;Cheremnykh, Klimushkin, and Kostarev, 2014;Cheremnykh, Klimushkin, and Mager, 2016). In Section 2 we review the derivation of the governing equations that describe the radial structure of the perturbations.…”

Section: Introductionmentioning

confidence: 99%

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Corrugation Instability of a Coronal Arcade

et al. 2017

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We analyse the behaviour of linear magnetohydrodynamic perturbations of a coronal arcade modelled by a half-cylinder with an azimuthal magnetic field and nonuniform radial profiles of the plasma pressure, temperature, and the field. Attention is paid to the perturbations with short longitudinal (in the direction along the arcade) wavelengths. The radial structure of the perturbations, either oscillatory or evanescent, is prescribed by the radial profiles of the equilibrium quantities. Conditions for the corrugation instability of the arcade are determined. It is established that the instability growth rate increases with decreases in the longitudinal wavelength and the radial wave number. In the unstable mode, the radial perturbations of the magnetic field are stronger than the longitudinal perturbations, creating an almost circularly corrugated rippling of the arcade in the longitudinal direction. For coronal conditions, the growth time of the instability is shorter than one minute, decreasing with an increase in the temperature. Implications of the developed theory for the dynamics of coronal active regions are discussed.

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Section: General Properties Of the Solutions For Symmetric And Antisysupporting

confidence: 92%

“…The opposite case, k r → 0, corresponds to the cut-offs (e.g. Cheremnykh, Klimushkin, and Kostarev, 2014). The cut-off surfaces are determined by the equation…”

Section: Alfvén Mode Eigenfunctions Symmetric With Respect To ϕ = π/2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Corrugation Instability of a Coronal Arcade

et al. 2017

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“…Rankin et al [2006] developed a fluid model of standing shear Alfvén waves that is applicable in a general magnetic field, such as the Tsyganenko 96 magnetic field [Tsyganenko and Stern, 1996;Tsyganenko and Peredo, 1994;Tsyganenko, 1995]. Cheremnykh et al [2014Cheremnykh et al [ , 2016 set up a two-dimensional (2-D) inhomogeneous cylinder model with hot plasma pressure and curved magnetic field and investigated the transverse structure and propagation of high m ULF waves. Klimushkin and Mager [2015] derived an Alfvén mode equation in finite-pressure plasma using the gyrokinetic approach and found that the only wave mode from the solution is the Alfvén-ballooning compressional wave.…”

Section: Introductionmentioning

confidence: 99%

Eigenmode analysis of compressional poloidal modes in a self‐consistent magnetic field

et al. 2017

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In this study, we simulate a self‐consistent magnetic field that satisfies force balance with a model ring current that is radially localized, axisymmetric, and has anisotropic plasma pressure. We find that the magnetic field dip forms near the high plasma pressure region with plasma β >∼ 0.6, and the formed magnetic dip becomes deeper for larger plasma β and also slightly deeper for larger anisotropy. We perform linear analysis on a ppol of self‐consistent equilibria for second harmonic compressional poloidal modes of sufficiently high azimuthal wave number. We investigate the effect of anisotropic pressure on the eigenfrequency of the poloidal modes and the characteristics of the compressional magnetic field component. We find that the eigenfrequency is reduced at the outer edge of the thermal pressure peak and increased at the inner edge. The compressional magnetic field component occurs primarily within 10° of the equator on both the inner and outer edges, with stronger compressional magnetic field component on the outer edge. Larger β and smaller anisotropy can increase the change of eigenfrequency and the strength of the compressional magnetic field component. The critical condition on plasma β and pressure anisotropy of an Alfvén ballooning instability is also identified.

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“…Besides, two-dimensional inhomogeneous axisymmetric models of the magnetosphere Journal of Geophysical Research: Space Physics 10.1002/2014JA020819 allow one to study the effects of the field line curvature and finite plasma pressure on the MHD modes. Such effects include coupling between the Alfvén and slow modes [Klimushkin, 1998;Leonovich and Kozlov, 2014;Cheremnykh et al, 2014] and the ballooning instability [Ohtani et al, 1989;Ohtani and Tamao, 1993;Liu, 1997]. Both effects are caused by the field line curvature, which cannot be considered in the box model of the magnetosphere.…”

Section: Introductionmentioning

confidence: 99%

Azimuthal inhomogeneity in the MHD waveguide in the outer magnetosphere

Mazur

Chuiko

2015

JGR Space Physics

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Geomagnetic field and plasma inhomogeneities in the outer equatorial part of the magnetosphere create a channel with low Alfvén speeds which spans from the nose to the far flanks of the magnetosphere, in both the morning and the evening sectors. This channel plays the role of a waveguide for fast magnetosonic waves. The waveguide eigenmodes and corresponding Alfvén resonance (field line resonance) regions are directly related to geomagnetic pulsations Pc3 and Pc5. U-shaped model of the waveguide allows for full analytical investigation of waveguide eigenmodes. Quantities such as mode wave numbers, group velocities, and their energy density distribution are found as functions of coordinate along the waveguide. The linkage of the waveguide magnetosonic oscillation energy to the Alfvén waves in the vicinity of the field line resonance deeper inside the magnetosphere is investigated, and corresponding energy leakage coefficient is found. Thus, the influence of longitudinal (i.e., azimuthal) waveguide inhomogeneity on wave propagation is analytically investigated. Obtained results can be used for interpretation of the observed wave power distribution in the frequency bands of geomagnetic pulsations Pc3 and Pc5, as well as for explanation of their spectral properties in the outer magnetosphere.

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On the structure of azimuthally small-scale ULF oscillations of hot space plasma in a curved magnetic field. Modes with continuous spectrum

Cited by 18 publications

References 40 publications

Corrugation Instability of a Coronal Arcade

Corrugation Instability of a Coronal Arcade

Eigenmode analysis of compressional poloidal modes in a self‐consistent magnetic field

Azimuthal inhomogeneity in the MHD waveguide in the outer magnetosphere

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