太阳耀斑电子束在日冕区产生的静电不稳定性

ELECTROSTATIC INSTABILITY EXCITED BY SOLAR FLARE ELECTRON BEAMS IN SOLAR CORONA

依据太阳耀斑爆发特征,建立了双耀斑电子束与日冕背景相作用的模型,数值结果表明,该等离子体系统将激发静电不稳定性,其时间增长率ω_i受耀斑热束密度与日冕背景密度比值(n_h/n_o)以及耀斑冷束相对论电子密度与日冕密度值(n_c/n_o)影响较大,并随它们增大而增大,其实频大小在耀斑热束等离子体频率附近。因此,此系统可激发大于1GHz的高频静电辐射,这些结果对揭示耀斑粒子在日冕空间传播行为有一定作用,并可用于探讨高频Ⅲ型射电机制。

In this paper, a model is presented for the interaction between solar flare electron beams which consist of a faster cold beam and a slower thermal beam, and coronal plasma. The calculation shows that a electrostatic instability can be excited in this situation. The growth rate of the instability becomes large when the themal beam density with lower velocity and the cold beam density with relativistic velocity increase. The real frequency of the instability is near the plasma frequency of the thermal beam electrons. Thus, a electrostatic emissions with frequencies larger than 1 GHz can be generated. These results show effects of the motion of solar flare particles in the corona. We may also apply this model to the generation mechanism for the solar Type- Ⅲ radio emission.