TY - JOUR
T1 - Can multi-threaded flux tubes in coronal arcades support a magnetohydrodynamic avalanche?
AU - Threlfall, J.
AU - Reid, J.
AU - Hood, A. W.
N1 - Funding Information:The authors gratefully acknowledge the financial support of STFC through the Consolidated grant, ST/S000402/1, to the University of St Andrews. J. Threlfall is grateful for support from the Division of Games Technology and Mathematics at Abertay University. A.W. Hood acknowledges support from ERC Synergy grant “The Whole Sun” (810218). The authors are grateful to Vasilis Archontis for instructive advice and fruitful discussion concerning the manuscript. This work used the Python programming language (van Rossum and de Boer, ), together with the NumPy (Harris et al., ) and Matplotlib (Hunter, ) packages. This work used the DIRAC 1, UKMHD Consortium machine at the University of St Andrews; the DiRAC Data Centric system at Durham University, operated by the Institute for Computational Cosmology; the DiRAC Data Analytic system at the University of Cambridge, operated by the University of Cambridge High Performance Computing Service; and the Cambridge Service for Data Driven Discovery (CSD3), which is operated by the University of Cambridge Research Computing. These systems are operated on behalf of the STFC DiRAC HPC Facility ( dirac.ac.uk ). The equipment was funded by National E-infrastructure capital grants (ST/K00042X/1 and ST/K001590/1), STFC capital grants (ST/K00087X/1, ST/H008861/1, ST/H00887X/1, ST/P002307/1, and ST/R002452/1), DiRAC Operations grants (ST/K003267/1 and ST/K00333X/1), and STFC operations grant ST/R00689X/1. DiRAC is part of the National E-Infrastructure.
Publisher Copyright: © 2021, The Author(s).
PY - 2021/8/16
Y1 - 2021/8/16
N2 - Magnetohydrodynamic (MHD) instabilities allow energy to be released from stressed magnetic fields, commonly modelled in cylindrical flux tubes linking parallel planes, but, more recently, also in curved arcades containing flux tubes with both footpoints in the same photospheric plane. Uncurved cylindrical flux tubes containing multiple individual threads have been shown to be capable of sustaining an MHD avalanche, whereby a single unstable thread can destabilise many. We examine the properties of multi-threaded coronal loops, wherein each thread is created by photospheric driving in a realistic, curved coronal arcade structure (with both footpoints of each thread in the same plane). We use three-dimensional MHD simulations to study the evolution of singleand multi-threaded coronal loops, which become unstable and reconnect, while varying the driving velocity of individual threads. Experiments containing a single thread destabilise in a manner indicative of an ideal MHD instability and consistent with previous examples in the literature. The introduction of additional threads modifies this picture, with aspects of the model geometry and relative driving speeds of individual threads affecting the ability of any thread to destabilise others. In both single- and multi-threaded cases, continuous driving of the remnants of disrupted threads produces secondary, aperiodic bursts of energetic release.
AB - Magnetohydrodynamic (MHD) instabilities allow energy to be released from stressed magnetic fields, commonly modelled in cylindrical flux tubes linking parallel planes, but, more recently, also in curved arcades containing flux tubes with both footpoints in the same photospheric plane. Uncurved cylindrical flux tubes containing multiple individual threads have been shown to be capable of sustaining an MHD avalanche, whereby a single unstable thread can destabilise many. We examine the properties of multi-threaded coronal loops, wherein each thread is created by photospheric driving in a realistic, curved coronal arcade structure (with both footpoints of each thread in the same plane). We use three-dimensional MHD simulations to study the evolution of singleand multi-threaded coronal loops, which become unstable and reconnect, while varying the driving velocity of individual threads. Experiments containing a single thread destabilise in a manner indicative of an ideal MHD instability and consistent with previous examples in the literature. The introduction of additional threads modifies this picture, with aspects of the model geometry and relative driving speeds of individual threads affecting the ability of any thread to destabilise others. In both single- and multi-threaded cases, continuous driving of the remnants of disrupted threads produces secondary, aperiodic bursts of energetic release.
U2 - 10.1007/s11207-021-01865-7
DO - 10.1007/s11207-021-01865-7
M3 - Article
VL - 296
JO - Solar Physics
JF - Solar Physics
SN - 0038-0938
IS - 8
M1 - 120
ER -