High-voltage pulse testing of cables on Hawk

Summary form only given, as follows. The Hawk facility at NRL was used to pulse test Dielectric Sciences 2158 cables to voltages in excess of 900 kV. The motivation for the testing was to assess the utility of these cables to connect elements in a high-impedance inductive voltage adder system. A high voltage pulse was launched at both ends of a long length of cable to obtain high voltage by wave adding in the middle of the cable while limiting high-voltage complications at the power feeds to the cables. The pulse width was controlled with a point-plane electron-beam diode. The cables tested were approximately 160´ long, with a one-way transit time of 240-ns. A pulse with a risetime less than 240-ns launched into both ends of the cable would add to double the voltage in the middle portion of the cable. The cables were connected to the output of one sub-Marx of the Hawk Marx bank, inside the oil tank. A resistive voltage divider was used to monitor the voltage input to the cable, and Rogowski coils to monitor the current input to each cable end. A point-plane electron-beam diode was also connected to the Marx output. The gap closure associated with this diode was used as timed closing switch to terminate the high voltage portion of the pulse. The stored energy of the Marx was dissipated in the damping resistors that were installed between the Marx and the cable, and the cable and the diode. Four lengths of cable were tested. The cable is designed for use as 69 kV AC power cable. Three of the four cables survived pulses in excess of 900 kV before failing, and the fourth cable failed at over 700 kV. Extensive results of the tests on the 2158 cables are presented.