Science and technological developments: article

Аnnotation: In 1970-1980, several experiments were carried out in the USSR to investigate the possibilities of using powerful pulsed MHD generators in geoelectric research. The first experiment in the world geophysical practice on deep electromagnetic sounding of the Earth's crust with a pulsed MHD generator was the experiment at the Garm test site in Tajikistan. It was assumed that a sharp increase in the power of the source used for sounding makes it possible to investigate changes in the electrical parameters of the Earth's crust to the depths of the location of the focal zones of earthquakes. According to the head of work on the use of MHD generators in the practice of geophysical research, academician E.P. Velikhov, cited in one of the publications, "The Garm geophysical test site played the role of the first field laboratory for the use of pulsed MHD generators in geophysics." In connection with the 35th anniversary of the beginning of electrical resistivity monitoring with a pulsed MHD generator at Garm, the main results of this experiment, the performed instrumental and methodological developments and their influence on experiments with MHD generators in other regions are briefly listed. In addition to geophysical studies at the Pamir-1 MHD installation, various experiments were carried out to improve the MHD generator itself, to change the shape of the generated current pulses in order to be able to use them for electromagnetic sounding by various methods. In particular, experiments were carried out to increase the output voltage of the MHD generator, generation of alternating current, and some others. A method of frequency electromagnetic sounding of the Earth's crust has been developed and new data have been obtained on the deep structure of the Garm test site. In parallel with soundings with powerful single current pulses, research was carried out on the development of soundings with long-acting electric generators based on the use of methods for stacking weak signals. Precision equipment was developed and produced in small series for soundings with periodic pulse sequences, powerful generators of continuous operation with high stability of current in the load were used for electric dipole soundings. A unique experiment on long-term precision monitoring by the method of vertical electrical sounding has been carried out.