Alfvén Resonances, Forced Magnetic Reconnection and Model of Solar Flares

2003 ◽  
Author(s):  
C. Uberoi
Keyword(s):  
Magnetic Reconnection ◽  
Solar Flares ◽  
Forced Magnetic Reconnection

scholarly journals The effects of density inhomogeneities on the radio wave emission in electron beam plasmas

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Xin Yao ◽  
Patricio A. Muñoz ◽  
Jörg Büchner ◽  
Xiaowei Zhou ◽  
Siming Liu
Keyword(s):  
Magnetic Reconnection ◽  
Radio Wave ◽  
Solar Flares ◽  
Electron Beams ◽  
Distribution Functions ◽  
Plasma Emission ◽  
Langmuir Waves ◽  
Radio Emissions ◽  
Density Inhomogeneities ◽  
Effects Of Density

Type III radio bursts are radio emissions associated with solar flares. They are considered to be caused by electron beams travelling from the solar corona to the solar wind. Magnetic reconnection is a possible accelerator of electron beams in the course of solar flares since it causes unstable distribution functions and density inhomogeneities (cavities). The properties of radio emission by electron beams in an inhomogeneous environment are still poorly understood. We capture the nonlinear kinetic plasma processes of the generation of beam-related radio emissions in inhomogeneous plasmas by utilizing fully kinetic particle-in-cell code numerical simulations. Our model takes into account initial electron velocity distribution functions (EVDFs) as they are supposed to be created by magnetic reconnection. We focus our analysis on low-density regions with strong magnetic fields. The assumed EVDFs allow two distinct mechanisms of radio wave emissions: plasma emission due to wave–wave interactions and so-called electron cyclotron maser emission (ECME) due to direct wave–particle interactions. We investigate the effects of density inhomogeneities on the conversion of free energy from the electron beams into the energy of electrostatic and electromagnetic waves via plasma emission and ECME, as well as the frequency shift of electron resonances caused by perpendicular gradients in the beam EVDFs. Our most important finding is that the number of harmonics of Langmuir waves increases due to the presence of density inhomogeneities. The additional harmonics of Langmuir waves are generated by a coalescence of beam-generated Langmuir waves and their harmonics.

scholarly journals Theory of Flares and MHD Jets

1998 ◽  
Vol 188 ◽  
pp. 9-12 ◽  
Author(s):  
Kazunari Shibata
Keyword(s):  
Numerical Modeling ◽  
Magnetic Reconnection ◽  
Solar Flares ◽  
Model Application ◽  
Reconnection Model

Recent development on the theory and numerical modeling of solar flares and jets is reviewed with emphasis on the magnetic reconnection model. Application to protostellar flares and jets is also discussed.

scholarly journals Hard X-ray Spectrum of the Above-the-Looptop Source in Impulsive Solar Flares

2000 ◽  
Vol 195 ◽  
pp. 413-414
Author(s):  
S. Masuda
Keyword(s):  
Magnetic Reconnection ◽  
Energy Release ◽  
Solar Flares ◽  
Count Rate ◽  
High Quality ◽  
X Ray ◽  
Flare Energy

Extended AbstractThe Hard X-ray Telescope (HXT: Kosugi et al. 1991) onboard Yohkoh has observed that, in impulsive solar flares, a hard X-ray source is located above the apex of a soft X-ray flaring loop, in addition to double footpoint sources (Masuda et al. 1994, 1995). This observation suggests that flare energy-release, probably magnetic reconnection, takes place not in the soft X-ray loop but above the loop. It is important to derive the hard X-ray spectrum of the above-the-looptop source accurately in order to understand how electrons are energized there. The above-the-looptop source was most clearly observed during the 13 January 1992 flare. However, the count rate, especially in the H-band (53–93 keV), is too small to synthesize high-quality images and to derive an accurate spectrum.

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