arXiv subjects

P S Cally

Publications and source records attributed to P S Cally.

2 recordsLinked to original sources

arXiv2013

Modelling Fast-Alfvén Mode Conversion Using SPARC

We successfully utilise the SPARC code to model fast-Alfvén mode conversion in the region $c_A \gg c_S$ via 3-D MHD numerical simulations of helioseismic waves within constant inclined magnetic field configurations. This was achieved only after empirically modifying the background density and gravitational stratifications in the upper layers of our computational box, as opposed to imposing a traditional Lorentz Force limiter, to ensure a manageable timestep. We found that the latter approach inhibits the fast-Alfvén mode conversion process by severely damping the magnetic flux above the surface.

astro-ph.SR↗

arXiv2010

Resonant Absorption as Mode Conversion? II. Temporal Ray Bundle

A fast-wave pulse in a simple, cold, inhomogeneous MHD model plasma is constructed by Fourier superposition over frequency of harmonic waves that are singular at their respective Alfven resonances. The pulse partially reflects before reaching the resonance layer, but also partially tunnels through to it to mode convert to an Alfven wave. The exact absorption/conversion coefficient for the pulse is shown to be given precisely by a function of transverse wavenumber tabulated in Paper I of this sequence, and to be independent of frequency and pulse width.

astro-ph.SR↗