2

Essential progress in experiments on dense plasma heating by a high-power electron beam was achieved at the GOL-3 facility. The electron beam with ~0.8 MeV energy, ~30 kA current, ~8 os pulse duration, and ~150 kJ total energy content heated deuterium plasma of ~10 21 m-3 density up to 2-3 keV temperature [1]. The confinement time in these experiments was ~1 ms. The high electron temperature in the linear trap was obtained due to 1000-fold suppression of longitudinal electron thermal conductivity during the beam pulse that is provided by a microturbulence, the latter is excited in the process of the beam relaxation in the plasma [2]. The achieved plasma parameters support our vision of a multiple mirror trap as the alternative path to a fusion reactor. The key physical problem for a multimirror-based reactor is keeping turbulent suppression of axial heat flow during the entire plasma burning pulse by injection of a long-pulse electron beam. Such a beam should sustain turbulence level strong enough to suppress electron transport along magnetic field. In the presented experiments two-fold increase in the beam duration (up to ~12 os) allows us to study dynamics of the electron distribution function during beam-plasma interaction. OPERATION REGIME AND DIAGNOSTICS Two significant parameters were different in the present experiments comparing to the standard scenario [1] listed above. The beam generator was modified in order to get longer beam generation. In new diode configuration the beam duration increases at the expense of the beam current (Fig. 1), total energy content remains the same. The beam current density i