| Popis: |
Successful application of inductive energy storage depends critically on the performance of the opening switch. The new Hawk generator at NRLI is used in plasma opening switch (POS) experiments in the 1-/spl mu/s conduction time regime to study long conduction time POS physics. In this experiment, different POS configurations were used, including various switch to load distances and different cathode center conductor radii. The load was an e-beam diode. Peak load powers of 0.5 TW, with load current risetimes of 20 ns and current transfer efficiencies of 80%, were achieved with a POS conduction time of 0.75 /spl mu/s using a 5 cm diam cathode. Typically, 40 kJ were coupled into the diode, which is 20% of the energy stored in the Hawk capacitance. The data indicate that above a critical load impedance the final switch gap, as determined from magnetic insulation arguments, is fixed to 2.5-3 mm, independent of conduction current and center conductor radius. Above this critical load impedance, current is shunted into the transition section between the switch and the load such that the voltage remains constant. At lower impedance values, the load voltage decreases in proportion to the load impedance. This critical load impedance is then the optimum impedance for maximum load power. Increasing the cathode magnetic field by conducting more current (up to a limit) or by decreasing the cathode center conductor radius at a given current level allows the switch to remain insulated at a higher voltage. Peak load voltages up to 1.7 MV were achieved using a 5 cm diam center conductor, a factor of 2 higher than that obtained with a 10 cm diam center conductor and 2.7 times higher than the erected Marx voltage (640 kV). |
