Review of the experimental results for the last two years on study of dense plasma heating and confinement in a long multimirror trap GOL-3 is presented. This facility is an open trap for confinement of hot (0.1-1 keV) dense (1015-1016 cm−3) plasma. The plasma heating is provided by a high-power electron beam (1 MeV, 30 kA, 8 μs) with energy content of up to 200 kJ. The upgrade to full-scale corrugation of a magnetic field was completed at the facility during last two years. In the 12-meter solenoid the multimirror sections of 4-m-length were made at the both ends of the solenoid (Bmax/Bmin = 5,2 / 3,2 T, cell length is 22 cm). The modified source of preliminary plasma was put in operation for improvement of macroscopically stable beam transport through the plasma column. New diagnostics were developed for the experiments. Search of optimal conditions for confinement of plasma with ~1015 cm−3 density and high ion temperature, and also for macroscopically stable system “electron beam - plasma” was carried out in the new configuration of facility. As a result of the experiments the plasma with density of (1-2)·1015 cm−3, neTe+niTi =(0.5-2)·1015 keV/cm3 and confinement time of 100-200 microseconds in a multimirror trap is obtained. The observations of high ion temperature and mechanism of ion heating is discussed in the paper.