Context. Radio bursts and their fine structures are an integral part of solar flares. Fine in particular used for diagnostics flare processes. The so-called zebras belong to the most important such structures. Aims. We analyze seven zebra events order search spatial variations plasma density magnetic field zebra-stripe sources. Methods. improved method estimating gyroharmonic numbers frequencie...

[1] On 12 November 2001, the European Incoherent Scatter (EISCAT) high-frequency (HF) radio wave transmitter facility, operating in O-mode at 5.423 MHz with 550 MW effective radiated power, produced artificial optical rings which appeared immediately at transmitter turn-on and collapsed into blobs after 60 s while descending in altitude. A similar descent in altitude was observed in the EISCAT ...

Artificial ionospheric plasmas descending from the background F-region have been observed on multiple occasions at the High Frequency Active Auroral Research Program (HAARP) facility since it reached full 3.6 MW power. Proximity of the transmitter frequency to the 2nd harmonic of the electron gyrofrequency (2fce) has been noted as a requirement for their occurrence, and their disappearance afte...

It is well known that the ionospheric plasma response to high-power HF radio waves changes drastically as the heater frequency approaches harmonics of the electron gyrofrequency. These include changes in the spectrum of the stimulated electromagnetic emission, reduction in the anomalous absorption of low-power diagnostic waves propagating through the heated volume, and reduction in the large sc...