Experimental development of radiographic sources on TriMeV

Summary form only given. High-brightness flash X-ray sources are needed for penetrating dynamic radiography for a variety of DOE Defense Programs applications. Various bremsstrahlung source experiments have been conducted on the TriMeV accelerator (3 MV, 60 /spl Omega/, 20 ns) in search of the best diode and focusing configuration in the 2-3 MV range. Three classes of candidate diodes were examined: paraxial focusing with gas transport, immersed magnetic field, and rod pinch. The best result for the paraxial diode was 8 rad at 1 meter from the source with a 6-mm diameter X-ray spot. For the immersed magnetic field, the best shot produced 4.1 rad with a 2.6-mm spot using 0.5-mm cathode immersed in a 17-T solenoidal field. The rod pinch diode demonstrated very reproducible radiographic spots between 0.75 and 0.8 mm in diameter, producing 1 rad. This represents a factor of seven improvement in the TriMeV flash radiographic capability above the original paraxial diode to a figure of merit (dose/spot diameter/sup 2/)>1.7 rad/mm/sup 2/. These results culminate a nine-month technology development effort performed in collaboration with Mission Research Corporation, Bechtel Nevada, Los Alamos National Laboratory, the Naval Research Laboratory, Pulse Sciences Inc., and the Atomic Weapons Establishment, and offer new avenues for upgrading existing pulsed power-driven flash radiographic systems.