Paraxial diodes on RITS-3

The paraxial diode is the workhorse X-ray source at AWE for flash radiography of hydrodynamic experiments. It uses a gas filled cone to focus a 30-40 kA, 5 to 10 MV electron beam onto a tantalum target to produce a source 5-7 mm across. Future plans for a new hydrodynamics facility at AWE call for this diode to be fielded at a higher voltage on an inductive voltage adder (IVA) machine. The current machines at AWE are based upon single pulse forming line (SPFL) technology. To gain some experience with IVA technology and paraxial diodes, a series of shots were fired on RITS-3 at Sandia National Labs. Over 30 shots were fired on RITS-3 to optimise and investigate aspects of paraxial diode operation. The main concern with using RITS-3 was the excess current (/spl sim/110 kA) that would be dumped into the vacuum envelope and whether it would effect diode performance. The results that were obtained showed that this was not the case. On RITS-3 a best performance of 57R@1 m from a 5.7 mm spot was recorded, very similar to performance seen on comparable X-ray machines at AWE.