274 research outputs found
Phenomenon of Alfvénic vortex shedding
Generation of Alfvenic (magnetohydrodynamic) vortices by the interaction of compressible plasma flows with magnetic-field-aligned blunt obstacles is modeled in terms of magnetohydrodynamics. It is found that periodic shedding of vortices with opposite vorticity is a robust feature of the interaction in a broad range of plasma parameters: for plasma beta from 0.025 to 0.5, and for the flow speeds from 0.1 to 0.99 of the fast magnetoacoustic speed. The Strouhal number is the dimensionless ratio of the blunt body diameter to the product of the period of vortex shedding and the inflow speed. It is found to be consistently in the range 0.15-0.25 in the whole range of parameters. The induced Alfvenic vortices are compressible and contain spiral-armed perturbations of the magnetic field strength and plasma mass density up to 50%-60% of the background values. The generated electric current also has the spiral-armed structuring
Spin-wave Talbot effect in thin ferromagnetic film
The Talbot effect has been known in optics since XIX century and found
various technological applications. In this paper, we demonstrate with the help
of micromagnetic simulations this self-imaging phenomenon for spin waves
propagating in a thin ferromagnetic film magnetized out-of-plane. We show that
the main features of the obtained Talbot carpets for spin waves can be
described, to a large extent, by the approximate analytical formulas yielded by
the general analysis of the wave phenomena. Our results indicate a route to a
feasible experimental realisation of the Talbot effect at low and high
frequencies and offer interesting effects and possible applications in
magnonics.Comment: 10 pages, 10 figure
- …