Pulse step modulation to produce very fast solid state pulses

Summary form only given. We have extended the Pulse Step Modulation (PSM) technique, originally invented by Swanson, to very fast pulses (This concept is originally found in US Patent #4,403,197, "Amplifier Employing Digital Modulator Circuit" 1983 by Hillmer I Swanson). The unique feature of the PSM circuit is that when a single device turns off, the parallel diode begins to conduct. In conventional series circuits, when a device opens and the rest of the devices are closed, that device will fail due to overvoltage. The reason for this difference is that the power supplies for each PSM stage are attached to only that stage. As long as the diode is fast enough and the charging method doesn't unnecessarily connect the stages, the series device failure mode of devices is completely eliminated. We present the design and operating results from units operating at 2 kV, 5000 A, 10 kV, 200 A, and 50 kV, 200 A. The critical issue in this technology is the charging of the intermediate, cascaded stages. We have investigated multi-turn chokes, and air core charging transformers. Novel charging systems can extend the utility of this technology to arbitrarily high charge voltages.