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Numerical simulations of helicity condensation in the solar corona
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | DeVore, C. R. Zurbuchen, T. H. Zhao, L. Antiochos, S. K. |
| Copyright Year | 2015 |
| Description | The helicity condensation model has been proposed by Antiochos (2013) to explain the observed smoothness of coronal loops and the observed buildup of magnetic shear at filament channels. The basic hypothesis of the model is that magnetic reconnection in the corona causes the magnetic stress injected by photospheric motions to collect only at those special locations where prominences form. In this work we present the first detailed quantitative MHD simulations of the reconnection evolution proposed by the helicity condensation model. We use the well-known ansatz of modeling the closed corona as an initially uniform field between two horizontal photospheric plates. The system is driven by applying photospheric rotational flows that inject magnetic helicity into the system. The flows are confined to a finite region on the photosphere so as to mimic the finite flux system of, for example, a bipolar active region. The calculations demonstrate that, contrary to common belief, coronal loops having opposite helicity do not reconnect, whereas loops having the same sense of helicity do reconnect. Furthermore, we find that for a given amount of helicity injected into the corona, the evolution of the magnetic shear is insensitive to whether the pattern of driving photospheric motions is fixed or quasi-random. In all cases, the shear propagates via reconnection to the boundary of the flow region while the total magnetic helicity is conserved, as predicted by the model. We discuss the implications of our results for solar observations and for future, more realistic simulations of the helicity condensation process. |
| File Size | 1887327 |
| Page Count | 39 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20150011090 |
| Archival Resource Key | ark:/13960/t4sj6gq9c |
| Language | English |
| Publisher Date | 2015-05-20 |
| Access Restriction | Open |
| Subject Keyword | Corona Magnetic Reconnection Magnetic Fields Magnetic Flux Solar Corona Magnetohydrodynamics Coronal Loops Direct Numerical Simulation Twisting Computational Fluid Dynamics Shear Flow Fluid Flow Condensing Boundary Conditions Cosmic Rays Photosphere Magnetic Field Reconnection Helical Flow Solar Flux Mathematical Models Solar Magnetic Field Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
