Masao Shigeta

Fast-charging Blumlein pulse forming line

A fast-charging, discharge-switch-free Blumlein pulse forming line has been developed for high-voltage pulsed power generation. In the BL, a saturable charging inductor (CI) of amorphous metallic core is utilized and, as a result, fast-charging (charging time ≈220 ns) is obtained with a reduced prepulse. In addition, by using CI as a step-up transformer, the impedance of the output pulse can be converted to 4Z, Z, Z/4. By using the BL with a Marx generator of 300 kV and 1.1 kJ, an output of —580 kV at 24 kA and a pulse length of 60 ns are obtained, with a current rise time of less than 16 ns. The energy transfer efficiency of the line (output pulse energy/charging energy of a pulse forming line) is evaluated to be more than 92%.

All-solid-state excitation circuit using saturable transformer for excimer laser excitation

To reduce the load on switching devices, a new type of all-solid-state excitation circuit has been successfully developed, where only one GTO thyristor is utilized in the switching device and a saturable transformer is used as the magnetic pulse compressor. We have used a saturable transformer with a winding ratio of 1:7. The initial pulse of 5.5 kV, 1.7 kA, 1.0 kA/microsecond(s) was transferred to the output pulse of 32.7 kV, 8.7 kA, 282 kA/ns. Employing this circuit for XeCl-excimer laser, we have succeeded in lasing the output energy of approximately 30 mJ/pulse.