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The variations of the ionospheric current in the lower ionosphere and the plasma density of the upper ionosphere have been studied based on the monitoring of the horizontal component of the geomagnetic field induction and height-frequency sounding of the critical frequency of the ionosphere F layer at the Moscow Observatory. It is shown that, in the spectra of time variations of the geomagnetic field and the critical frequency of the F2 layer in the range of planetary waves in winter, there are both harmonics associated with solar activity and harmonics corresponding to quasi-5-, 10-, and 16-day planetary waves. The involvement of geomagnetic field registration data for a 20-year time interval (from 2001 to 2020) have made it possible to identify more subtle effects, namely, the harmonics associated with the modulation effect of longer period variations and tidal effects are identified. [ABSTRACT FROM AUTHOR]

A conceptual design of the lower hybrid current drive (LHCD) system for the upgraded T-15 tokamak (RNC Kurchatov Institute, Moscow) is presented. A tentative theoretical analysis, including extensive numerical simulations of different antenna types and LH wave propagation as well as estimation of LHCD efficiency, is carried out. The analysis has shown the possibility of launching a 4-5 MW radio frequency power through one tokamak port and driving up to a 1 MA LH current at a plasma density of 2-3 × 1013 cm-3. The most suitable design of the whole LHCD system and the antenna, in particular, is discussed as well as the main technical problems of the T-15 LHCD project. [ABSTRACT FROM AUTHOR]