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An alternative mechanism is proposed for the generation of harmonics of the electron plasma frequency due to the development of explosive instability in a system of interpenetrating electron and proton flows in the solar atmosphere. The efficiency of the new mechanism in comparison with the earlier discussed mechanisms involving multistage processes of nonlinear interaction of waves in plasma is determined. It is shown that the development of explosive instability can lead to the excitation of the second and third harmonics of the plasma frequency with comparable amplitudes., Comment: 8 pages

We analyze complex zebra patterns and fiber bursts during type-IV solar radio bursts on August 1, 2010. It was shown that all of the main details of sporadic zebra patterns can be explained within the model of zebra patterns and fiber bursts during the interaction of plasma waves with whistlers. In addition, it was shown that the major variations in the stripes of the zebra patterns are caused by the scattering mechanism of fast particles on whistlers, which leads to the transition of whistler instability from the normal Doppler effect to an anomalous one., Comment: 20 pages, 11 figures

The reason for the occurrence of different elements of the fine structure of solar radio bursts in the decimeter and centimeter wavelength ranges has been determined based on all available data from terrestrial and satellite observations. In some phenomena, fast pulsations, a zebra structure, fiber bursts, and spikes have been observed almost simultaneously. Two phenomena have been selected to show that the pulsations of radio emission are caused by particles accelerated in the magnetic reconnection region and that the zebra structure is excited in a source, such as a magnetic trap for fast particles. The complex combination of unusual fiber bursts, zebra structure, and spikes in the phenomenon on December 1, 2004, is associated with a single source, a magnetic island formed after a coronal mass ejection., Comment: 20 pages, 18 figures; accepted in Geomagnetism and Aeronomy 2017

Discussion about the nature of zebra-structure (ZS) in the type IV radio bursts continues, despite the ten proposed models. First of all, this is due to the wide variety of stripes in each new phenomenon, when the explanation of all the fine details by any one mechanism becomes impossible. The most widespread explanation is the emission at different levels of double plasma resonance (DPR), sequential on the height surfaces in the magnetic trap, where the upper hybrid frequency ($\omega_{UH}$) becomes equal to the integer of electronic cyclotron harmonics $s\omega_{Be}: \omega_{UH} = (\omega_{Pe}^2 + \omega_{Be}^2)^{1/2} = s\omega_{Be}$ (Zheleznyakov, Zlotnik, 1975, Winglee, Dulk, 1986, Kuznetsov & Tsap (2007)). An important alternative mechanism is the interaction of plasma waves with the whistlers: $l + w \Rightarrow t$ (Chernov, 1976, 2006). Here, we will show the possibility of explaining the main features of the zebra stripes in the model with whistlers, using the example of the phenomenon on August 1, 2010., Comment: 4 pages, 3 figures, Oral report at the conference: XII Solar System Plasma Conference, February 6, 2017, Space Research Institute of RAS, Moscow, Russia