A Special Radio Spectral Fine Structure Used for Plasma Diagnostics in Coronal Magnetic Traps
A Special Radio Spectral Fine Structure Used for Plasma Diagnostics in Coronal Magnetic Traps
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用于日冕磁阱等离子体诊断的特殊射电频谱精细结构
DOI：
10.1007/s11207-009-9327-8
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发表时间：
2009
期刊：
影响因子：
2.8
通讯作者：
G. Mann
中科院分区：
文献类型：
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作者：
E. Zlotnik;V. Zaitsev;H. Aurass;G. Mann
在波茨坦天体物理研究所进行的观测中，报告了太阳射电爆发发射的动态频谱的米 - 分米计中的光谱精细结构的特定组合。我们描述和解释了快速漂移(III型爆发式)吸收连续辐射包层中斑马图案的出现。提出了这种复杂光谱图样产生的一种可能机制，即必然会产生多个平衡分量的日冕等离子体。所提出的机制是基于这样一个事实：在快电子束通过日冕的过程中，损失锥不稳定性(由产生连续体的磁陷阱中捕获的电子引起)被熄灭。结果，在吸收中出现快速漂移猝发，在低本底发射时斑马图案变得可见。这种斑马图案是由一群在横向速度上具有非平衡分布的电子产生的。在没有光束的情况下，图案在更强的连续统的背景下是看不见的。结果表明，该机制对不同电子系综的分布参数很敏感。因此，在动态射电频谱中的影响相对较少，但它的适当存在表明，在耀斑日冕中同时存在不同的电子系综可能是相当频繁的情况。这可以解释X射线光子谱到电子能谱去卷积的一些问题。
A specific combination of spectral fine structures in meter – decimeter dynamic spectra of solar radio burst emission is reported in observations carried out at the Astrophysical Institute Potsdam. We describe and interpret the occurrence of zebra patterns in fast drifting (type III burst-like) envelopes of absorbed continuum emission. A possible mechanism of the origin of such an involved spectral pattern is put forward, leading to a necessarily multinonequlibrium component coronal plasma. The suggested mechanism is based on the fact that during the passage of a fast electron beam through the corona the loss cone instability (which is caused by electrons captured in a magnetic trap generating the continuum) is quenched. As result, a fast drift burst appears in absorption, and the zebra pattern becomes visible on the low background emission. This zebra pattern is generated by a group of electrons with a nonequilibrium distribution over transverse velocities. In the absence of the beam the pattern is invisible against the background of the stronger continuum. It is shown that the mechanism is sensitive to the distribution parameters of the different electron ensembles. Therefore the effect in dynamic radio spectra is comparatively rare but its proper existence underlines that the simultaneous presence of different ensembles of electrons in the flaring corona can be quite a frequent situation. This can explain some problems in deconvolving X-ray photon spectra to electron energy spectra.