Microsecond plasma opening switch experiments on Hawk with an E-beam diode load

The Hawk generator is used in plasma opening switch (POS) experiments in the 1-μs conduction time regime to study long conduction time switch physics. Peak load powers of 0.7 TW with 55 kJ delivered to the diode - 20% energy efficiency - were achieved with a POS. The data indicate that above a critical load impedance the final switch gap size is limited to about 3 mm. This limits the voltage. Maximum load power is obtained at this critical impedance. Increasing the cathode magnetic field - by conducting more current or by decreasing the cathode radius - allows the fixed-gap POS to remain insulated at a higher voltage. Peak load voltages up to 2 MV were achieved with a 2.5 cm diam cathode, a factor of 2.8 higher than the Marx voltage. Load powers were up to 70% higher with a plasma-filled diode (PFD) used in conjunction with the POS for short POS conduction times. The switch gap may be larger (>; 3 mm) on these short conduction PFD shots.