scholarly journals Relaxation of magnetic field relative to plasma density during solar flares

2012 ◽  
Vol 8 (S294) ◽  
pp. 589-590
Author(s):  
Sijie Yu ◽  
Yihua Yan ◽  
Baolin Tan
Keyword(s):  
Magnetic Field ◽  
Detailed Analysis ◽  
Plasma Density ◽  
Solar Flares ◽  
Scale Height ◽  
Emission Source ◽  
Field Scale ◽  
Broadband Radio ◽  
The Magnetic Field ◽  
Density Scale

AbstractWe investigated the variations of 74 microwave ZP structures observed by Chinese Solar Broadband Radio Spectrometer at 2.6–3.8 GHz in 9 solar flares, found that the ratio between the plasma density scale height LN and the magnetic field scale height LB in emission source displays a tendency of decrease during the flaring process, indicates that LB increases faster than the LN during solar flares. The detailed analysis of the step-wise decrease of LN/LB in three typical X-class flares reveals the magnetic field relaxation relative to the plasma density.

scholarly journals Millimeter and Microwave Activity of the Sun

1990 ◽  
Vol 142 ◽  
pp. 457-465 ◽  
Author(s):  
M. R. Kundu ◽  
S. M. White
Keyword(s):  
Magnetic Field ◽  
Gamma Rays ◽  
Solar Flares ◽  
Gamma Ray ◽  
High Spatial Resolution ◽  
High Resolution Imaging ◽  
The Sun ◽  
Millimeter Wavelengths ◽  
Resolution Imaging ◽  
The Magnetic Field

The emission of solar flares at millimeter wavelengths is of great interest both in its own right and because it is generated by the energetic electrons which also emit gamma rays. Since high-resolution imaging at gamma-ray energies is not presently possible, millimeter observations can act as a substitute. Except for that class of flares known as gamma-ray flares the millimetric emission is optically thin. It can be used as a powerful diagnostic of the energy distribution of electrons in solar flares and its evolution, and of the magnetic field. We have carried out high-spatial-resolution millimeter observations of solar flares this year using the Berkeley-Illinois-Maryland Array (BIMA), and report on the preliminary results in this paper (Kundu et al 1990; White et al 1990). We also report some recent results obtained from multifrequency observations using the VLA (White et al 1990).

The interphase surface energy in some pure and impure superconductors

1960 ◽  
Vol 255 (1282) ◽  
pp. 407-426 ◽  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Surface Energy ◽  
Detailed Analysis ◽  
Energy Parameter ◽  
Transverse Magnetic ◽  
Superconducting Phase ◽  
Interphase Surface ◽  
Dilute Alloys ◽  
The Magnetic Field

A new method has been developed for obtaining relative values of the surface energy parameter, Δ, in superconductors. It involves the measurement of the resistance of thin films subjected to a transverse magnetic field. The method has been applied to tin, indium and aluminium and to dilute alloys of the first two. The principal new results are that Δ is 1⋅48 times larger in indium than in tin and that the addition of impurity to either metal lowers Δ without changing the nature of its temperature dependence. These conclusions are compared with current theories of the interphase surface energy. An attempt has been made to deduce the absolute magnitude of Δ, which requires a detailed analysis of the way in which the last traces of the superconducting phase are eliminated from the film by the action of the magnetic field. The analysis is necessarily over-simplified but it does give a figure for Δ in pure tin which is reasonably consistent with the previous estimates of Faber and Sharvin.

scholarly journals Inferring the Magnetic Field Asymmetry of Solar Flares from the Degree of Polarisation at Millimetre Wavelengths

Solar Physics ◽  
2020 ◽  
Vol 295 (6) ◽  
Author(s):  
D. F. Silva ◽  
P. J. A. Simões ◽  
R. F. Hidalgo Ramírez ◽  
A. Válio
Keyword(s):  
Magnetic Field ◽  
Solar Flares ◽  
The Magnetic Field

Solar flare forecasting model using 3D magnetic field data

2020 ◽  
Author(s):  
Xin Huang
Keyword(s):  
Magnetic Field ◽  
Deep Learning ◽  
Solar Flare ◽  
Solar Flares ◽  
Field Data ◽  
Active Regions ◽  
Forecasting Model ◽  
Magnetic Field Data ◽  
The Magnetic Field

<p>Solar flares originate from the release of the energy stored in the magnetic field of solar active regions. Generally, the photospheric magnetograms of active regions are used as the input of the solar flare forecasting model. However, solar flares are considered to occur in the low corona. Therefore, the role of 3D magnetic field of active regions in the solar flare forecast should be explored. We extrapolate the 3D magnetic field using the potential model for all the active regions during 2010 to 2017, and then the deep learning method is applied to extract the precursors of solar flares in the 3D magnetic field data. We find that the 3D magnetic field of active regions is helpful to build a deep learning based forecasting model.</p>

scholarly journals Magnetic Instabilities in Stellar Atmospheres

1983 ◽  
Vol 71 ◽  
pp. 545-558
Author(s):  
E.R. Priest
Keyword(s):  
Magnetic Field ◽  
Solar Flares ◽  
Impulsive Phase ◽  
Coronal Magnetic Field ◽  
Stellar Atmospheres ◽  
Stored Energy ◽  
Global Instability ◽  
Magnetohydrodynamic Instability ◽  
Kink Instability ◽  
The Magnetic Field

ABSTRACT.The extensive theory for magnetohydrodynamic instability of a flux tube is briefly reviewed, together with its application to tokamaks and solar flares. In a star a single coronal loop whose footprints are anchored in the dense photosphere may become unstable to the kink instability when it is twisted too much. Magnetic arcades may also be subject to an eruptive instability when they are sheared too much. After the eruption the magnetic field closes back down by reconnection and continues to heat the plasma long after the impulsive phase. Global instability of a large part of the coronal magnetic field is also possible when the stored energy is too great.

scholarly journals A New Explanation for Flares on dMe Stars

1989 ◽  
Vol 104 (2) ◽  
pp. 357-360
Author(s):  
G.M. Simnett
Keyword(s):  
Magnetic Field ◽  
Energy Transfer ◽  
Solar Corona ◽  
Solar Flares ◽  
Active Regions ◽  
Strong Fields ◽  
Stellar Flares ◽  
Self Consistent ◽  
The Magnetic Field

AbstractIt has been proposed that non-thermal ions dominate the energy transfer at the onset of solar flares. Here we examine this hypothesis in the context of flares on dMe stars. If the magnetic field in the stellar corona is significantly larger than that in the solar corona, and if strong fields in the photosphere, analagous to active regions, are absent, then a self-consistent explanation of stellar flares may be formulated.

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