Local properties of magnetic reconnection in nonlinear resistive and extendedmagnetohydrodynamic toroidal simulations of the sawtooth crash
We diagnose local properties of magnetic reconnection during a sawtooth crash employing the threedimensional toroidal, extendedmagnetohydrodynamic (MHD) code M3DC ^{1}. To do so, we sample simulation data in the plane in which reconnection occurs, the plane perpendicular to the helical (m, n) = (1, 1) mode at the q = 1 surface, where m and n are the poloidal and toroidal mode numbers and q is the safety factor. We study the nonlinear evolution of a particular test equilibrium in a nonreduced field representation using both resistiveMHD and extendedMHD models. We find growth rates for the extendedMHD reconnection process exhibit a nonlinear acceleration and greatly exceed that of the resistiveMHD model, as is expected from previous experimental, theoretical, and computational work. We compare the properties of reconnection in the two simulations, revealing the reconnecting current sheets are locally different in the two models and we present the first observation of the quadrupole outofplane Hall magnetic field that appears during extendedMHD reconnection in a 3D toroidal simulation (but not in resistiveMHD). We also explore the dependence on toroidal angle of the properties of reconnection as viewed in the plane perpendicular to the helical magnetic field, finding qualitative and quantitative effects duemore »
 Authors:

^{[1]}
;
^{[1]};
^{[2]};
^{[2]}
 West Virginia Univ., Morgantown, WV (United States)
 Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
 Publication Date:
 Grant/Contract Number:
 AGS0953463; AC0209CH11466; NNX10AN08A; NNX16AG76G; NNX16AF75G
 Type:
 Accepted Manuscript
 Journal Name:
 Plasma Physics and Controlled Fusion
 Additional Journal Information:
 Journal Volume: 59; Journal Issue: 2; Journal ID: ISSN 07413335
 Publisher:
 IOP Science
 Research Org:
 Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; fusion; magnetic reconnection; sawteeth
 OSTI Identifier:
 1344528
 Alternate Identifier(s):
 OSTI ID: 1336487
Beidler, M. T., Cassak, P. A., Jardin, S. C., and Ferraro, N. M.. Local properties of magnetic reconnection in nonlinear resistive and extendedmagnetohydrodynamic toroidal simulations of the sawtooth crash. United States: N. p.,
Web. doi:10.1088/13616587/59/2/025007.
Beidler, M. T., Cassak, P. A., Jardin, S. C., & Ferraro, N. M.. Local properties of magnetic reconnection in nonlinear resistive and extendedmagnetohydrodynamic toroidal simulations of the sawtooth crash. United States. doi:10.1088/13616587/59/2/025007.
Beidler, M. T., Cassak, P. A., Jardin, S. C., and Ferraro, N. M.. 2016.
"Local properties of magnetic reconnection in nonlinear resistive and extendedmagnetohydrodynamic toroidal simulations of the sawtooth crash". United States.
doi:10.1088/13616587/59/2/025007. https://www.osti.gov/servlets/purl/1344528.
@article{osti_1344528,
title = {Local properties of magnetic reconnection in nonlinear resistive and extendedmagnetohydrodynamic toroidal simulations of the sawtooth crash},
author = {Beidler, M. T. and Cassak, P. A. and Jardin, S. C. and Ferraro, N. M.},
abstractNote = {We diagnose local properties of magnetic reconnection during a sawtooth crash employing the threedimensional toroidal, extendedmagnetohydrodynamic (MHD) code M3DC1. To do so, we sample simulation data in the plane in which reconnection occurs, the plane perpendicular to the helical (m, n) = (1, 1) mode at the q = 1 surface, where m and n are the poloidal and toroidal mode numbers and q is the safety factor. We study the nonlinear evolution of a particular test equilibrium in a nonreduced field representation using both resistiveMHD and extendedMHD models. We find growth rates for the extendedMHD reconnection process exhibit a nonlinear acceleration and greatly exceed that of the resistiveMHD model, as is expected from previous experimental, theoretical, and computational work. We compare the properties of reconnection in the two simulations, revealing the reconnecting current sheets are locally different in the two models and we present the first observation of the quadrupole outofplane Hall magnetic field that appears during extendedMHD reconnection in a 3D toroidal simulation (but not in resistiveMHD). We also explore the dependence on toroidal angle of the properties of reconnection as viewed in the plane perpendicular to the helical magnetic field, finding qualitative and quantitative effects due to changes in the symmetry of the reconnection process. Furthermore, this study is potentially important for a wide range of magnetically confined fusion applications, from confirming simulations with extendedMHD effects are sufficiently resolved to describe reconnection, to quantifying local reconnection rates for purposes of understanding and predicting transport, not only at the q = 1 rational surface for sawteeth, but also at higher order rational surfaces that play a role in disruptions and edgeconfinement degradation.},
doi = {10.1088/13616587/59/2/025007},
journal = {Plasma Physics and Controlled Fusion},
number = 2,
volume = 59,
place = {United States},
year = {2016},
month = {12}
}