A flexible pulse power supply for EM- and ETC-launchers

For the 10 MJ-railgun PEGASUS a pulse forming network (PFN) was developed and built up which consists of 200 units with an energy of 50 kJ each. The units are completely equipped by semiconducting switches (thyristors and diodes). Due to a particular design they are extremely compact and have a blocking voltage of 12 kV and a current capability of more than 90 kA. For the railgun application a maximum current of up to 2 MA can be generated. Due to the modular set-up of the pulse forming network the current pulse can be shaped in an almost arbitrary manner. First results with this PFN by applying a railgun as load is reported. Investigations took place to apply the same PFN as energy source for an ETC-launcher as well. First investigations showed that the overvoltage peaks occurring with this application are causing damage of the pulse forming units. Measurements had to be taken in order to protect the pulse power supply against these harmful events. The experiments revealed that the units are triggered by disturbances yielded by the ETC-load. To analyse these malfunctions simulations with the electrical code PSpice have been performed. The simulations showed that by carrying out small modifications the PFN should be qualified as energy source for ETC-experiments. The 50 kJ-modules, changed in this way, were applied to an ETC-load. The experiments confirmed that a PFN consisting of several modified units is excellently qualified as energy source for an ETC-launcher because due to its highly modular configuration it allows generation of current shapes particularly adaptable to the load.