Laboratory study of interaction of magnetoplasma irregularities produced by several radio-frequency heating sources

The dynamics of a group of narrow field-aligned plasma density irregularities is studied using the large-scale KROT plasma device. The chosen experimental conditions are similar to the conditions in the ionosphere of the Earth, where such irregularities develop under the impact of high-power, high-frequency radio waves. In our laboratory experiment, the irregularities are created by a set of rf antennas arranged in a row across the ambient magnetic field due to the heating of electrons and subsequent redistribution of the plasma. Near the heating sources, the irregularities have the form of a set of channels with reduced plasma density, which develop almost independently. At the same time, the relaxation time of a group of neighboring irregularities differs from that of each single irregularity. Evolution of density perturbations at the periphery of the heating region differs for a single irregularity and for a group of irregularities significantly. These effects are probably due to eddy currents excited by each of the irregularities in the background plasma, since narrow irregularities can develop in the "unipolar" thermal diffusion regime. The preliminary experimental results are consistent with the theoretical predictions of unipolar diffusion and excitation of eddy currents. Published by AIP Publishing.