First experiments on the gasdynamic trap

The paper describes an experimental device called ''gasdynamic trap'' and reports the results of the first experiments on it. The gasdynamic trap is a mirror machine with a spacing of 7 m between the mirrors, minimum magnetic field of 0.2 T and a mirror ratio varying between 25 and 80. The preliminary plasma generated in the gas discharge source is injected into the trap through one of the magnetic mirrors. The plasma is then heated by the injector of six atomic hydrogen beams with a total power of 5 MW, an atom energy of 20 keV and a pulse duration of 0.25 ms. In the different operating regimes of the plasma source, the trap could be filled with plasma at densities from 5x1012cm-3 to 1014cm-3 and temperatures in the range from 3 eV to 30 eV. The plasma filling dynamics of the trap are in good agreement with gasdynamic evaluations. During filling the plasma in the trap is MHD stable, regardless of the shape of the field lines in the expanders. This indicates the presence of stabilization of the plasma at the ends, which is ensured by the high electrical conductivity of the plasma in the source. After the source is switched off, the plasma MHD stability becomes sensitive to the shape of the field lines in the expanders. In particular, the plasma decay time in the trap is greater when the field lines in the expander have a favourable curvature than when the curvature is unfavourable. (author). 12 refs, 5 figs, 2 tabs