Global coronal and heliospheric magnetic field modelling for Solar Orbiter

2021 ◽  
Author(s):  
Thomas Wiegelmann ◽  
Thomas Neukirch ◽  
Iulia Chifu ◽  
Bernd Inhester
Keyword(s):  
Magnetic Field ◽  
Solar Rotation ◽  
Coronal Magnetic Field ◽  
Important Research ◽  
Parker Spiral ◽  
Important Research Topic ◽  
Mhd Equilibria ◽  
Solar Wind Flow ◽  
Nonlinear Force

<p>Computing the solar coronal magnetic field and plasma<br>environment is an important research topic on it's own right<br>and also important for space missions like Solar Orbiter to<br>guide the analysis of remote sensing and in-situ instruments.<br>In the inner solar corona plasma forces can be neglected and<br>the field is modelled under the assumption of a vanishing<br>Lorentz-force. Further outwards (above about two solar radii)<br>plasma forces and the solar wind flow has to be considered.<br>Finally in the heliosphere one has to consider that the Sun<br>is rotating and the well known Parker-spiral forms.<br>We have developed codes based on optimization principles<br>to solve nonlinear force-free, magneto-hydro-static and<br>stationary MHD-equilibria. In the present work we want to<br>extend these methods by taking the solar rotation into account.</p>

scholarly journals An Optimization Principle for Computing Stationary MHD Equilibria with Solar Wind Flow

Solar Physics ◽  
2020 ◽  
Vol 295 (10) ◽  
Author(s):  
Thomas Wiegelmann ◽  
Thomas Neukirch ◽  
Dieter H. Nickeler ◽  
Iulia Chifu
Keyword(s):  
Magnetic Field ◽  
Free Field ◽  
Coronal Magnetic Field ◽  
Optimization Method ◽  
Field Configuration ◽  
Optimization Principle ◽  
Mhd Equilibria ◽  
Solar Wind Flow ◽  
Nonlinear Force ◽  
Flow Effects

Abstract In this work we describe a numerical optimization method for computing stationary MHD equilibria. The newly developed code is based on a nonlinear force-free optimization principle. We apply our code to model the solar corona using synoptic vector magnetograms as boundary condition. Below about two solar radii the plasma $\beta $ β and Alfvén Mach number $M_{A}$ M A are small and the magnetic field configuration of stationary MHD is basically identical to a nonlinear force-free field, whereas higher up in the corona (where $\beta $ β and $M_{A}$ M A are above unity) plasma and flow effects become important and stationary MHD and force-free configuration deviate significantly. The new method allows for the reconstruction of the coronal magnetic field further outwards than with potential field, nonlinear force-free or magnetostatic models. This way the model might help to provide the magnetic connectivity for joint observations of remote sensing and in-situ instruments on Solar Orbiter and Parker Solar Probe.

scholarly journals An optimization principle for computing stationary MHD equilibria with solar wind flow

2020 ◽  
Author(s):  
Thomas Wiegelmann ◽  
Thomas Neukirch ◽  
Dieter Nickeler ◽  
Iulia Chifu
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Coronal Magnetic Field ◽  
Field Vector ◽  
Source Surface ◽  
Solar Chromosphere ◽  
Wind Flow ◽  
Solar Wind Flow ◽  
Nonlinear Force ◽  
The Magnetic Field

<p>Knowledge about the magnetic field and plasma environment is important<br>for almost all physical processes in the solar atmosphere. Precise<br>measurements of the magnetic field vector are done routinely only in<br>the photosphere, e.g. by SDO/HMI. These measurements are used as<br>boundary condition for modelling the solar chromosphere and corona,<br>whereas some model assumptions have to be made. In the low-plasma-beta<br>corona the Lorentz-force vanishes and the magnetic field<br>is reconstructed with a nonlinear force-free model. In the mixed-beta<br>chromosphere plasma forces have to be taken into account with the<br>help of a magnetostatic model. And finally for modelling the global<br>corona far beyond the source surface the solar wind flow has to<br>be incorporated within a stationary MHD model.<br>To do so, we generalize a nonlinear force-free and magneto-static optimization<br>code by the inclusion of a field aligned compressible plasma flow.<br>Applications are the implementation of the solar wind on<br>global scale. This allows to reconstruct the coronal magnetic field further<br>outwards than with potential field, nonlinear force-free and magneto-static models.<br>This way the model might help in future to provide the magnetic connectivity<br>for joint observations of remote sensing and in-situ instruments on Solar<br>Orbiter and Parker Solar Probe.</p>

Modeling and forecasting the background solar wind with data-driven physics-based models

2020 ◽  
Author(s):  
Michael Lavarra ◽  
Rui Pinto ◽  
Alexis Rouillard ◽  
Athanasios Kouloumvakos ◽  
Alessandro Bemporad ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Rotation ◽  
Coronal Magnetic Field ◽  
Physical Parameters ◽  
Transient Heating ◽  
Modeling And Forecasting ◽  
Solar Wind Flow ◽  
Remote Observation ◽  
Slow Wind

<p>The quasi-steady solar wind flow is a key component of space weather, being the source of corotating density structures that perturb planetary atmospheres and affect the propagation of impulsive perturbations (such as CME). Fast and slow wind streams develop at different places in the solar atmosphere, reflecting the global distribution of the coronal magnetic field during solar cycle and its consequences for heat and mass transport across the corona. I will present recent advances on global solar wind simulations that provides robust and fully physics-based predictions of the structure and physical parameters of the solar wind based on a multi-1D approach (MULTI-VP, ISAM). Such advances relate to the driving the models with time-dependant magnetogram data, to the inclusion of transient heating phenomena, and to switching from a fluid to a multi-species description of the solar wind. The model was also driven by daily synchronic magnetograms (ADAPT) for a full solar rotation and the simulation results were compared to UVCS plane-of-sky data.The simulations produce a large range of synthetic observables (e.g multi-spacecraft in-situ measurements, white-light and EUV imagery) meant to be compared to data from current and future missions (e.g Solar Orbiter and Parker Solar Probe), and to establish physiccal connections between remote observation of the solar surface and corona and the interplanetary medium.</p>

scholarly journals Nonlinear force-free modeling of magnetic fields in flare-productive active regions

2015 ◽  
Vol 11 (S320) ◽  
pp. 167-174
Author(s):  
M. S. Wheatland ◽  
S. A. Gilchrist
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Boundary Data ◽  
Numerical Solutions ◽  
Free Field ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Nonlinear Force ◽  
The Magnetic Field ◽  
Force Free Field

AbstractWe review nonlinear force-free field (NLFFF) modeling of magnetic fields in active regions. The NLFFF model (in which the electric current density is parallel to the magnetic field) is often adopted to describe the coronal magnetic field, and numerical solutions to the model are constructed based on photospheric vector magnetogram boundary data. Comparative tests of NLFFF codes on sets of boundary data have revealed significant problems, in particular associated with the inconsistency of the model and the data. Nevertheless NLFFF modeling is often applied, in particular to flare-productive active regions. We examine the results, and discuss their reliability.

A Discussion on the physics of the solar atmosphere - Physics of the solar atmosphere

1976 ◽  
Vol 281 (1304) ◽  
pp. 415-426
Keyword(s):  
Magnetic Field ◽  
Transition Region ◽  
Solar Atmosphere ◽  
Solar Rotation ◽  
Active Regions ◽  
Rotation Velocity ◽  
Coronal Magnetic Field ◽  
Velocity Fields ◽  
Field Structure ◽  
Magnetic Field Structure

A summary is given on recent results on the physics of the quiet solar atmosphere, and active regions. This includes: solar rotation, velocity fields and waves, magnetic field concentration, the transition region, coronal magnetic field structure, and prominences.

Exact equilibria for nonlinear force-free magnetic fields with its applications to astrophysics and fusion plasmas

2014 ◽  
Vol 80 (2) ◽  
pp. 173-195 ◽  
Author(s):  
S. M. Moawad
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Physics ◽  
Coronal Magnetic Field ◽  
Fusion Plasmas ◽  
Magnetic Structures ◽  
Magnetic Flux Ropes ◽  
Solar Prominences ◽  
Confinement Fusion ◽  
Nonlinear Force

AbstractKnowledge of the structure of coronal magnetic field originating from the photosphere is relevant to the understanding of many solar activity phenomena, e.g. flares, solar prominences, coronal loops, and coronal heating. In most of the existing literature, these loop-like magnetic structures are modeled as force-free magnetic fields (FFMF) without any plasma flow. In this paper, we present several exact solution classes for nonlinear FFMF, in both translational and axisymmetric geometries. The solutions are considered for their possible relevance to astrophysics and solar physics problems. These are used to illustrate arcade-type magnetic field structures of the photosphere and twisted magnetic flux ropes through the coronal mass ejections (CMEs), as well as magnetic confinement fusion plasmas.

Tailored growth of in situAl4SiC4 in laser melted aluminum melt

2015 ◽  
Vol 29 (08) ◽  
pp. 1550019 ◽  
Author(s):  
Fei Chang ◽  
Dongdong Gu
Keyword(s):  
Energy Density ◽  
Materials Science ◽  
Solidification Process ◽  
Research Topic ◽  
Important Research ◽  
Growth Mechanisms ◽  
Applied Physics ◽  
Ceramic Phase ◽  
Important Research Topic

The crystallization and growth of in situ crystals during non-equilibrium laser rapid melting/solidification process is an important research topic in the fields of both Applied Physics and Materials Science. The present paper studies the development mechanisms of in situ formed Al 4 SiC 4 ceramic phase within the selective laser melted SiC / AlSi10Mg composites. Two different-structured Al 4 SiC 4 having strip and particle morphologies were disclosed and their growth mechanisms were influenced by laser linear energy density (LED). An elevated LED resulted in a larger degree formation of strip-structured Al 4 SiC 4 with the gradually coarsened crystal sizes in its length and thickness. The homogeneously dispersed particle-shaped Al 4 SiC 4 exhibited a considerably refined nanostructure with a proper increase in LED, but showing a significant coarsening of particles at an excessive LED.

scholarly journals Computing nonlinear force free coronal magnetic fields

2003 ◽  
Vol 10 (4/5) ◽  
pp. 313-322 ◽  
Author(s):  
T. Wiegelmann ◽  
T. Neukirch
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Boundary Conditions ◽  
Random Noise ◽  
Coronal Magnetic Field ◽  
Optimization Method ◽  
Numerical Code ◽  
Coronal Magnetic Fields ◽  
Nonlinear Force ◽  
Free Fields

Abstract. Knowledge of the structure of the coronal magnetic field is important for our understanding of many solar activity phenomena, e.g. flares and CMEs. However, the direct measurement of coronal magnetic fields is not possible with present methods, and therefore the coronal field has to be extrapolated from photospheric measurements. Due to the low plasma beta the coronal magnetic field can usually be assumed to be approximately force free, with electric currents flowing along the magnetic field lines. There are both observational and theoretical reasons which suggest that at least prior to an eruption the coronal magnetic field is in a nonlinear force free state. Unfortunately the computation of nonlinear force free fields is way more difficult than potential or linear force free fields and analytic solutions are not generally available. We discuss several methods which have been proposed to compute nonlinear force free fields and focus particularly on an optimization method which has been suggested recently. We compare the numerical performance of a newly developed numerical code based on the optimization method with the performance of another code based on an MHD relaxation method if both codes are applied to the reconstruction of a semi-analytic nonlinear force-free solution. The optimization method has also been tested for cases where we add random noise to the perfect boundary conditions of the analytic solution, in this way mimicking the more realistic case where the boundary conditions are given by vector magnetogram data. We find that the convergence properties of the optimization method are affected by adding noise to the boundary data and we discuss possibilities to overcome this difficulty.

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