A Special Radio Spectral Fine Structure Used for Plasma Diagnostics in Coronal Magnetic Traps

• DOI: 10.1007/s11207-009-9327-8
• Publication Date: 2009-03-16T10:59:28Z
• Authors: E. Y. Zlotnik; V. V. Zaitsev; H. Aurass; G. Mann
• Keywords: 01 natural sciences; 7. Clean energy; 0105 earth and related environmental sciences

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.