Ultra-fast flash X-ray pulses produced by Blumlein devices

The flash X-ray systems developed at the University of Texas at Dallas (UTD) centers on two critical subassemblies: (1) a Blumlein pulsed power source and (2) an X-ray diode properly designed and matched to the pulse forming line. The pulse generator consists of either a single or several triaxial Blumleins. For multiple lines, Blumleins are stacked in series at one end and charged in parallel and synchronously commutated with a single switching element at the other end. In this way, relatively low charging voltages are multiplied to give a high discharge voltage across an X-ray diode. Extensive characterization of these Blumlein pulsers have been performed over the past several years. Results indicate that they are capable of producing high-power waveforms with risetimes and repetition rates in the range of 0.1-50 ns and 1-1000 Hz, respectively, using a conventional thyratron, spark gap, or photoconductive switch. Our recent efforts have for the first time resulted in implementation and demonstration of high-power stacked Blumlein pulsers commutated by a single photoconductive switch. Presently, these devices reliably produce 50-100 MW output waveforms with pulse durations of 1-3 ns and risetimes as fast as 150 ps. Prospects for producing X-rays with such fast-switching devices are discussed.