太阳耀斑非热电子动力学研究

The Study of Non-thermal Electron Kinetics During Solar Flares

主要讨论太阳耀斑过程中非热电子动力学过程的理论模型以及在硬X射线和射电波段的观测特征。现在广为接受的非热电子动力学过程的模型是"俘获+沉降"模型,由电子的加速、注入、沉降、俘获及能量损失5个部分组成。射电和硬X射线爆发是非热电子在输运过程中与磁场、背景等离子体及其产生的波等相互作用的产物,是非热电子动力学过程的即时反映。通过分析射电和硬X射线辐射的流量、谱和成像特征,可以研究非热电子的空间分布和时间演化,研究非热电子输运过程中发生的碰撞、辐射、散射、波-波、波-粒相互作用等物理过程,研究耀斑磁场、背景等离子体特征,进而为太阳耀斑的磁场结构、太阳大气分布、磁重联模型的研究提供理论和观测依据。

In this paper,we introduce the model of the kinetic process of non-thermal electrons during the solar flares and the observational characteristics of radio and hard X-ray bursts. The general accepted model for non-thermal electrons kinetics during solar flares is trap-plus-precipitation model,which is composed of five phases：acceleration,injection,trap,precipitation, and energy loss.There are several acceleration mechanisms such as electric DC field acceleration, stochastic acceleration and shock acceleration and so on.The energy,spatial and momentum distribution of non-thermal electrons accelerated from each mechanism are different and the accelerated electrons are injected into the flare loops with different ways.For electric DC field acceleration,the accelerated electrons depart from the reconnection region directly and the original distribution is unaffected by the injection.However,the electrons accelerated by stochastic acceleration and shock acceleration would be trapped inside the magnetic mirror of acceleration region and they are injected into the flare loops while they are scattered out of the trap region. The injected electrons with pitch angle less than the loss-cone angle move freely through the flare loops.The other ones with pitch angle greater than the loss-cone angle are trapped inside the flare loops and bounced between the magnetic mirror points until they are scattered into the loss cone by proper pitch angle scattering mechanisms or lose energy by interactions with the local plasma.All the energetic electrons,which get to the chromosphere,lose their energy by emission and collision and stay in the chromosphere afterward.During the kinetics process of non-thermal electrons,the non-thermal electrons interact with magnetic field,local plasma et al.and produce radiations.Radio burst are produced both by gyrosynchrotron radiation when the non-thermal electrons spiral the magnetic field and plasma emission.Hard X-ray is emitted by free-free radiation with non-thermal electrons colliding with the local plasma.Both of them are the instantaneous signals of the non-thermal electron kinetics.By analyzing the fluxes,spectra, and sources of radio and hard X-ray burst,we can study the spatial,energy and temporal distribution of non-thermal electrons,the wave-wave interaction,wave-particle interaction,collision, emission,diffusion during the transport,and the characteristic of magnetic field and local plasma.We can provide theoretic and observational basis for magnetic structure of solar flares, solar atmosphere and magnetic reconnection.