Design, development and installation of pulsed high current test facility

Four high energy capacitor modules (of 200kJ each) have been connected in parallel to achieve high current (2.4MA) pulse (12–15μs) for conducting various pulsed power experiments. Railgap switches are being utilized in synchronous mode to transfer energy from high energy capacitor modules. The Railgap switches are operated in multichannel mode that enables large charge transfer in distributed mode with minimum switch inductance. Multichannel operation helps in achieving lower jitter and conduction delay along with minimum electrode erosion that is essential for the synchronized operation of switches. The initiation of several simultaneous arc channels along the electrode length in Railgap switch has a strong dependency on the gap voltage and rate at which the electric field changes within the gap. High trigger voltage and fast rate of rise (dV/dt >5kV/ns) are essential for existing Railgap switches for functioning in multichannel mode. Temporal characteristics of trigger pulse deteriorate when multiple Railgap switches are connected in parallel due to capacitive loading. To avoid the problem of capacitive loading, coaxial cable based pulse generator is designed and developed for synchronized, multi-channel discharge of all four modules. At 30kV of primary charging, the pulse generator produces around 60kV output pulse of 100ns duration (FWHM) with a rise time of better than 10ns (10%–90%) that correspond to dV/dt of >5kV/ns. At a charging voltage of 15kV, peak current of ∼1.3MA has been delivered to load.