Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition
Nonuniform plasma across an imposed magnetic field, such as those present in the solar atmosphere, can support collective Alfvénic oscillations with a characteristic damping time. The damped transverse oscillations of coronal loops are an example of this process. In ideal magnetohydrodynamics (MHD),...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-11-01
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| Series: | Physics |
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| Online Access: | https://www.mdpi.com/2624-8174/4/4/87 |
| _version_ | 1797455652966105088 |
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| author | Roberto Soler |
| author_facet | Roberto Soler |
| author_sort | Roberto Soler |
| collection | DOAJ |
| description | Nonuniform plasma across an imposed magnetic field, such as those present in the solar atmosphere, can support collective Alfvénic oscillations with a characteristic damping time. The damped transverse oscillations of coronal loops are an example of this process. In ideal magnetohydrodynamics (MHD), these transient collective motions are associated with quasi-modes resonant in the Alfvén continuum. Quasi-modes live in a non-principal Riemann sheet of the dispersion relation, and so they are not true ideal MHD eigenmodes. The present study considers the illustrative case of incompressible surface MHD waves propagating on a nonuniform interface between two uniform plasmas with a straight magnetic field parallel to the interface. It is explored how the ideal quasi-modes of this configuration change when the width of the nonuniform transition increases. It is found that interfaces with wide enough transitions are not able to support truly collective oscillations. A quasi-mode that can be related with a resonantly damped surface MHD wave can only be found in interfaces with sufficiently thin transitions. |
| first_indexed | 2024-03-09T15:57:23Z |
| format | Article |
| id | doaj.art-64c898b2dbad498fb35dab17e825242a |
| institution | Directory Open Access Journal |
| issn | 2624-8174 |
| language | English |
| last_indexed | 2024-03-09T15:57:23Z |
| publishDate | 2022-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Physics |
| spelling | doaj.art-64c898b2dbad498fb35dab17e825242a2023-11-24T17:26:38ZengMDPI AGPhysics2624-81742022-11-01441359137010.3390/physics4040087Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform TransitionRoberto Soler0Departament de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca, SpainNonuniform plasma across an imposed magnetic field, such as those present in the solar atmosphere, can support collective Alfvénic oscillations with a characteristic damping time. The damped transverse oscillations of coronal loops are an example of this process. In ideal magnetohydrodynamics (MHD), these transient collective motions are associated with quasi-modes resonant in the Alfvén continuum. Quasi-modes live in a non-principal Riemann sheet of the dispersion relation, and so they are not true ideal MHD eigenmodes. The present study considers the illustrative case of incompressible surface MHD waves propagating on a nonuniform interface between two uniform plasmas with a straight magnetic field parallel to the interface. It is explored how the ideal quasi-modes of this configuration change when the width of the nonuniform transition increases. It is found that interfaces with wide enough transitions are not able to support truly collective oscillations. A quasi-mode that can be related with a resonantly damped surface MHD wave can only be found in interfaces with sufficiently thin transitions.https://www.mdpi.com/2624-8174/4/4/87Sun: oscillationsSun: atmospherewavesmagnetohydrodynamics (MHD) |
| spellingShingle | Roberto Soler Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition Physics Sun: oscillations Sun: atmosphere waves magnetohydrodynamics (MHD) |
| title | Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition |
| title_full | Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition |
| title_fullStr | Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition |
| title_full_unstemmed | Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition |
| title_short | Exploring the Ideal MHD Quasi-Modes of a Plasma Interface with a Thick Nonuniform Transition |
| title_sort | exploring the ideal mhd quasi modes of a plasma interface with a thick nonuniform transition |
| topic | Sun: oscillations Sun: atmosphere waves magnetohydrodynamics (MHD) |
| url | https://www.mdpi.com/2624-8174/4/4/87 |
| work_keys_str_mv | AT robertosoler exploringtheidealmhdquasimodesofaplasmainterfacewithathicknonuniformtransition |