Studying travelling ionospheric disturbances from near-vertical ionosphere sounding with high temporal resolution
In this study, we analyze the near-vertical ionospheric sounding data obtained with a multipurpose digital chirp ionosonde. The ionosonde was recording ionograms once each minute. We analyzed the results of processing the datasets over three observational years from 2010 to 2012. Obtaining ionograms with a high temporal resolution allowed us to trace the dynamics and evolution of additional traces referred to as “cusps”, and also to combine ionograms with such traces into sequences. The percentage of ionograms containing cusps proved to be more than 10% of the overall number of ionograms. Thus, during daytime, the rate surpasses 30%, whereas, during nighttime, such ionograms are practically absent. The typical cusp lifetime proved to be 4-15 min, therefore, disturbed ionograms are much more rarely detected with standard vertical sounding ionosondes. The presence of such traces unambiguously evidences significant electron density horizontal gradients caused by travelling ionospheric disturbances (TIDs) with scales up to 50 km.
The analysis of a travelling ionospheric disturbance with non-linear ionization response
Abstract Ionograms from a triangular array of ionosondes are analysed to yield the characteristics of an internal gravity wave throughout the F-region. F1-region overlays, which measure the shape of the ionogram near the F1-cusp, give a good estimate of wave amplitude. An internal gravity wave generates a non-linear response in the ionospheric electron density profiles, which have the characteristics of thick ledges. The ionograms show external hooks associated with such ledges.
Microwave source with enhanced radiation power based on orbitron MASERs
We have proposed the design of high power microwave source in a vacuum tube based on the theory of negative mass instability. The proposed source does not operate based on a slow-wave structure but instead makes use of accelerated charged particles. In our structure, an electron emitter injects the charged particles into to the cavity. Emitted particles move around the anode, which leads to electron acceleration and emission of electromagnetic waves with a specific frequency. In this paper, we have enhanced the output power and frequency of microwave source by variation of particles initial energy and the number of anodes incorporating their specific arrangement and applied voltages. Working at room temperature, compactness, wide bandwidth, and tunability of output frequency are among the advantages of the proposed source.