Bremsstrahlung risetime shortening by diode geometry reconfiguration

Experimental and theoretical studies on one arm of the Aurora flash x-ray machine have indicated that it is possible to lower the risetime of the bremsstrahlung produced at a single Aurora diode by increasing the AK gap of the diode. In an experimental setup employing a cylindrically symmetrical toroidal cathode, the local spatial distribution of bremsstrahlung pulse shape at the thick tantalum converter was measured at 10 radial positions by 10 Compton diodes placed at the converter. Additionally, bremsstrahlung produced at distances of 2, 3, 4, and 5 meters from the converter was measured by Pilot B scintillation counters. As the AK gap was widened, the early part of the bremsstrahlung pulse was diverted in the radial direction of the magnetically insulated transmission line (MITL) feeding the diode. The bremsstrahlung risetime at 3 meters from the bremsstrahlung target was reduced from about 60 to 18 ns by increasing the AK gap from 11 to more than 19 inches.