A plasma-filled diode (PFD) technique is described for producing high dose-rate bremsstrahlung over small areas. A PFD was developed for this purpose using the Gamble II generator. For maximum dose-rate conditions, the short-circuit phase duration was 40 ns, after which the voltage increased to 1.8 MV and the total current in the diode was 0.5 MA. The X-ray pulsewidth was 8 ns, much less than the typical 50 ns pulsewidth with a vacuum diode. This PFD was adapted to the higher-current Saturn generator at 6-8 MA by making a 10-cm diameter circular array of 6, 9, or 12 isolated PFDs. Higher dose rates were obtained using fewer PFDs; about 1 10 12 rad/s with the 12-PFD array, 2 10 12 with nine PFDs and 4 10 12 with 6 PFDs. Analyses based on electrical and radiation diagnostics indicate that 40%-77% of the electrical current produces radiation at the time of maximum dose rate. The X-ray pulsewidth was typically 13-16 ns, less than the pulsewidth for standard (vacuum) bremsstrahlung diodes on Saturn. This system, with improvements in reproducibility, could provide a high dose-rate, small-area bremsstrahlung capability for high current generators.Index Terms-Bremsstrahlung, dose rate, plasma-filled diode (PFD), pulsed power.

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A series of experiments on the MEDUSA linear accelerator radiation test facility were performed to evaluate the difference in dose measured using different methods. Significant differences in dosimeter-measured radiation dose were observed for the different dosimeter types for the same radiation environments, and the results are compared and discussed in this report. 4 ACKNOWLEDGEMENTS

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Inductive Voltage Adder (IVA) accelerators were developed to provide high-current (100s of kA) power pulses at high voltage (up to 20 MV) using robust modular components. This architecture simultaneously resolves problems found in conventional pulsed and linear induction accelerators.A variety of highbrightness pulsed x-ray radiographic sources are needed from sub-megavolt to 16-MeV endpoints with greater source brightness (dose/spotz) than presently available. We are applying WA systems to produce very intense (up.to 75 TW/cma) electron beams for these flash radiographic applications.