scholarly journals Introduction of the vector potential to a linear MHD simulation code based on a real coordinate system

2016 ◽  
Vol 23 (10) ◽  
pp. 102509 ◽  
Author(s):  
W. Takado ◽  
Y. Matsumoto ◽  
K. Y. Watanabe ◽  
S. Tomioka ◽  
S. Oikawa
Keyword(s):  
Coordinate System ◽  
Vector Potential ◽  
Simulation Code ◽  
Mhd Simulation

Study of the Transition from MRI to Magnetic Turbulence via Parasitic Instability by a High-order MHD Simulation Code

2018 ◽  
Vol 853 (2) ◽  
pp. 174 ◽  
Author(s):  
Kenichiro Hirai ◽  
Yuto Katoh ◽  
Naoki Terada ◽  
Soshi Kawai
Keyword(s):  
High Order ◽  
Simulation Code ◽  
Mhd Simulation ◽  
Magnetic Turbulence

MHD simulation of solar flare by applying analytical energetic fast electron model

2020 ◽  
Author(s):  
Wenzhi Ruan ◽  
Rony Keppens
Keyword(s):  
Solar Flare ◽  
Plasma Density ◽  
Fast Electron ◽  
Thermal Conduction ◽  
Energetic Electron ◽  
Simulation Code ◽  
Electron Model ◽  
Mhd Simulation ◽  
Flare Loop ◽  
X Ray

<p>In order to study the evaporation of chromospheric plasma and the formation of hard X-ray (HXR) sources in solar flare events, we coupled an analytic energetic electron model with the multi-dimensional MHD simulation code MPI-AMRVAC. The transport of fast electrons accelerated in the flare looptop is governed by the test particle beam approach reported in Emslie et al. (1978), now used along individual field lines. Anomalous resistivity, thermal conduction, radiative losses and gravity are included in the MHD model. The reconnection process self-consistently leads to formation of a flare loop system and the evaporation of chromospheric plasma is naturally recovered. The non-thermal HXR emission is synthesized from the local fast electron spectra and local plasma density, and thermal bremsstrahlung soft X-ray (SXR) emission is synthesized based on local plasma density and temperature. We found that thermal conduction is  an efficient way to trigger evaporation flows. We also found that the generation of a looptop HXR source is a result of fast electron trapping, as evidenced by the pitch angle evolution. By comparing the SXR flux and HXR flux, we found that a possible reason for the “Neupert effect” is that the increase of non-thermal and thermal energy follows the same tendency.</p>

A Comment on Zeeman Effects in Rotation Spectra

1970 ◽  
Vol 25 (12) ◽  
pp. 2004 ◽  
Author(s):  
B.J. Howard ◽  
R.E. Moss
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Coordinate System ◽  
Gauge Transformation ◽  
Vector Potential ◽  
Molecular Vibrations ◽  
Centre Of Gravity ◽  
Elec Tromagnetic Field ◽  
Constant External Magnetic Field

Abstract Recently SUTTER et al. 1 obtained a Hamiltonian for a molecule in the presence of a constant external elec-tromagnetic field. (A similar Hamiltonian has been de-veloped 2 , but including molecular vibrations, relativis-tic corrections and allowance for the fact that the mo-lecular centre of gravity differs from the nuclear centre of gravity.) We believe that the Hamiltonian of Sutter et al. is not correct, since they make two errors of principle in performing their gauge transformation. They start with a Lagrangian expressed in terms of the particle positions, rn\ in a space-fixed coordinate system. Each particle is associated with an external vector potential,-^«' = rn', where H is the constant external magnetic field. At this stage a gauge transfor-mation may be performed: An'-+An'-VnX, (1)

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