Computational study of processes in plasma sheaths surrounding probes of various geometries

Spiral galaxies are surrounded by a widely distributed hot coronal gas and seem to be fed by infalling clouds of neutral hydrogen gas with low metallicity and high velocities. We numerically study plasma waves produced by the collisions of these high-velocity clouds (HVCs) with the hot halo gas and with the gaseous disk. In particular, we tackle two problems numerically: 1) collisions of HVCs with the galactic halo gas and 2) the dispersion relations to obtain the phase and group velocities of plasma waves from the equations of plasma motion as well as further important physical characteristics such as magnetic tension force, gas pressure, etc. The obtained results allow us to understand the nature of MHD waves produced during the collisions in galactic media and lead to the suggestion that these waves can heat the ambient halo gas. These calculations are aiming at leading to a better understanding of dynamics and interaction of HVCs with the galactic halo and of the importance of MHD waves as a heating process of the halo gas.

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“…In plasma physics, there exist several methods, how the plasma dynamics can be described and calculated, see e.g. [23], [24].…”

Section: Simulations Of Collisions Of Hvcs With Galactic Halomentioning

confidence: 99%

The collisions of high-velocity clouds with the galactic halo

Jelínek¹,

Hensler²

2011

Computer Physics Communications

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“…In plasma physics, there exist several methods of how the plasma dynamics can be described and calculated, as shown, e.g., in [15]- [18]. In our computer model, we describe the plasma dynamics in the coronal loop by the ideal MHD equations [19] …”

Section: A Numerical Solutions Of Mhd Equationsmentioning

confidence: 99%

Impulsively Generated Wave Trains in a Solar Coronal Loop

Jelínek

Karlický

2010

IEEE Trans. Plasma Sci.

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Impulsively generated fast magnetoacoustic wave trains in a solar coronal loop are numerically studied. The problem is considered as 2-D in space, and for the description, the full set of magnetohydrodynamic (MHD) equations is used. The numerical solution of the MHD equations is performed by means of the Lax-Wendroff algorithm on a uniformly structured mesh. The wavelet analysis of the obtained wave trains shows out the typical tadpole shapes, i.e., a narrow tail followed by a broadband head. In this paper, we discuss the propagation speed and periods of the wave trains as well as the shapes of the tadpoles in dependence on the plasma beta parameter. These studies are very important in connection with the observations because the tadpole signatures, firstly discovered during the solar eclipse in 1999 by the SECIS instrument, have been recently recognized also in decimetric type IV radio events by the Ondřejov radiospectrograph.

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