RESULTS OF RECENT EXPERIMENTS ON GDT DEVICE AFTER UPGRADE OF HEATING NEUTRAL BEAMS

The status of the experiments on the axially symmetric magnetic mirror device gas dynamic trap (GDT) is discussed. The plasma has been heated by skewed injection of 20-key, 3.5-MW, 5-ms deuterium/hydrogen neutral beams at the center of the device, which produces anisotropic fast ions. Neither enhanced transverse losses of the plasma nor anomalies in the fast ion scattering and slowing down were observed. Extension of neutral beam injection pulse duration from 1 to 5 ms resulted in an increase in the on-axis transverse beta (ratio of the transverse plasma pressure to magnetic field pressure) from 0.4 at the fast ion turning points near the end mirrors to about 0.6. The measured beta value is rather close to or even higher than that expected in different versions of the GDT-based 14-MeV neutron source for fusion materials testing. The density of fast ions with the mean energy of 10 to 12 keV reached 5 X 10(19) m(-3) near the turning points. The electron temperature at the same time reached approximate to 200 eV. The radial plasma losses were suppressed by sheared plasma rotation in the periphery driven by biasing of end wall segments and the radial limiter in the central solenoid.