Experiments on PIM in support of development of flash radiographic sources at 1 to 3 MV

The PIM pulsed power machine is an inductive voltage adder that is being used as a test-bed to determine the requirements of future radiographic accelerators in the 1 to 3 MV range. A 1.5 MV, 100 ns duration pulse is generated by a 10 Ohm water Blumlein. A prepulse reduction system reduces the prepulse to less than 3 kV allowing the machine to successfully drive a number of different types of e-beam diode. In the configuration used for recent experiments the output of the Blumlein is split into two in an oil insulated coaxial feed sharing the current between two induction cells. These add the voltage generated along a vacuum transmission line feeding the diode. That configuration is potentially capable of driving a 40 Ohm load at 2.5 MV. The machine can be reconfigured to drive only one induction cell and therefore provide a 10 Ohm 1.5 MV capability which may be used in testing lower impedance e-beam diodes for generating high brightness X-ray sources with a relatively soft spectrum. The data obtained in this work is also being used to improve our ability to model such machines and assess concepts for future accelerators.