Self-consistent, three-dimensional equilibrium effects on tokamak magnetic field ripple

Three-dimensional (3-d) magnetohydrodynamics (MHD) modeling is a key method for studying the interplanetary solar wind. In this paper, we introduce a new 3-d MHD solar wind model driven by the self-consistent boundary condition obtained from multiple observations and the Artificial Neural Network (ANN) machine learning technique. At the inner boundary, the magnetic field is derived using the magnetogram and potential field source surface extrapolation; the electron density is derived from the polarized brightness (pB) observations, the velocity can be deduced by an ANN using both the magnetogram and pB observations, and the temperature is derived from the magnetic field and electron density by a self-consistent method. Then, the 3-d interplanetary solar wind from CR2057 to CR2062 is modeled by the new model with the self-consistent boundary conditions. The modeling results present various observational characteristics at different latitudes, and are in better agreement with both the OMNI and Ulysses observations compared to our previous MHD model based only on photospheric magnetic field observations.

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Determining whether the squashing factor, Q, would be a good indicator of reconnection in a resistive MHD experiment devoid of null points

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936832 ◽

2020 ◽

Vol 633 ◽

pp. A92

Author(s):

J. Reid ◽

C. E. Parnell ◽

A. W. Hood ◽

P. K. Browning

Keyword(s):

Magnetic Field ◽

Magnetic Reconnection ◽

Coronal Loop ◽

Ohmic Heating ◽

Three Dimensional ◽

Necessary And Sufficient Condition ◽

Geometric Measure ◽

Self Consistent ◽

Necessary And Sufficient ◽

The Magnetic Field

The squashing factor of a magnetic field, Q, is commonly used as an indicator of magnetic reconnection, but few studies seek to evaluate how reliable it is in comparison with other possible reconnection indicators. By using a full, self-consistent, three-dimensional, resistive magnetohydrodynamic experiment of interacting magnetic strands constituting a coronal loop, Q and several different quantities are determined. Each is then compared with the necessary and sufficient condition for reconnection, namely the integral along a field line of the component of the electric field parallel to the magnetic field. Among the reconnection indicators explored, we find the squashing factor less successful when compared with alternatives, such as Ohmic heating. In a reconnecting magnetic field devoid of null points, our work suggests that Q, being a geometric measure of the magnetic field, is not a reliable indicator of the onset or a diagnostic of the location of magnetic reconnection in some configurations.

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Numerical simulations of magnetized winds of solar-like stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309030932 ◽

2008 ◽

Vol 4 (S259) ◽

pp. 415-416

Author(s):

Aline A. Vidotto ◽

M. Opher ◽

V. Jatenco-Pereira ◽

T. I. Gombosi

Keyword(s):

Magnetic Field ◽

Steady State ◽

Numerical Simulations ◽

Magnetic Energy ◽

Three Dimensional ◽

Terminal Velocity ◽

Mhd Equations ◽

Stellar Winds ◽

Self Consistent ◽

Crucial Parameter

AbstractWe investigate magnetized solar-like stellar winds by means of self-consistent three-dimensional (3D) magnetohydrodynamics (MHD) numerical simulations. We analyze winds with different magnetic field intensities and densities as to explore the dependence on the plasma-β parameter. By solving the fully ideal 3D MHD equations, we show that the plasma-β parameter is the crucial parameter in the configuration of the steady-state wind. Therefore, there is a group of magnetized flows that would present the same terminal velocity despite of its thermal and magnetic energy densities, as long as the plasma-β parameter is the same.

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