Pulse shaping experiments on the RITS-6 accelerator

The six cell inductive voltage adder (IVA) RITS-6 is a test bed for studying and improving the radiographic performance of various flash X-ray sources. RITS will be used to study the effect of the pulse shape predicted for the Hydrus IVA on the Self Magnetic Pinch (SMP) and paraxial radiographic diodes. The modification of RITS´s configuration to match the Hydrus IVA output pulse shape into simple diodes is described. Test results with the radiographic diodes will be presented in the future. The 10 cell Hydrus IVA was designed by L-3 Communications - Pulse Sciences for the Atomic Weapons Establishment (AWE) in England. The baseline Hydrus IVA is predicted to drive the nominally 40-Omega SMP to nearly 8 MV through its 80-Omega output MITL. The output pulse shape of the Hydrus IVA has two important features that have not been previously tested with radiographic diodes. One feature is a 20-ns duration foot preceding the fast rising main pulse. The other feature is a slowly rising ramp through the duration of the voltage pulse top which is predicted to counter the SMP diode´s falling impedance, thereby flattening the diode voltage. The output pulse shape of the RITS-6 accelerator fitted with its 80-Omega output MITL was modified to mimic that of the Hydrus IVA by adjusting the sequential timing of its six 8-Omega PFLs and by altering the relative closing times of each PFL´s self breaking main, sharpening, and prepulse switches. Circuit simulations predict that the modified RITS-6 will approximately reproduce the pulse shape of the Hydrus accelerator. Measured pulse shapes will be compared to predictions for both RITS and Hydrus with a large area electron beam diode.