Status of the AWE Hydrus IVA fabrication

The ten-module Hydrus Induction Voltage Adder, designed by L3 Communications - Pulse Sciences Division for AWE, builds on previous IVA experience in the US. Each of the ten modules comprises a 1.4 MV induction cell driven by a laser triggered gas switched Pulse Forming Line (PFL) in order to provide nanosecond order synchronisation, and hence excellent pulse reproducibility. The PFLs are charged by a single Marx through an oil-insulated transmission line. The outputs of the cells are added along a 22 metre long 80 ohm MITL to deliver an 11 MV forward going wave to the e-beam diode. The accelerator will be used for flash radiography by AWE utilising a Self Magnetic Pinch diode as the radiographic source. This diode operates at approximately 40 Ohms with the result that retrapping of the MITL sheath current occurs, reducing the diode voltage to ~ 7.5 MV, but increasing the load current to 200 kA. The detailed PFL design was previously prototyped and has been chosen to tailor the output pulse to compensate for the SMP diode's intra pulse impedance reduction and hence generate a relatively constant voltage during generation of the X-ray flash. The components of the Hydrus IVA are approaching completion at L3 Pulse Sciences at San Leandro, CA. All parts of the IVA are being procured by L-3 PS and delivered to San Leandro for subassembly. The major IVA subassemblies being fabricated comprise the Marx, oil line, PFL, cell, and stalk. Ancillary systems being fabricated comprise the control software, vacuum, water processing, oil processing, magnetic core reset, gas processing, data acquisition, and power supply. Subassemblies and subsystems are subject to a variety of QA tests which include high voltage testing of the Marx and its trigger, and a first-article PFL driving both a dummy load and a first-article cell. The status of the in-progress fabrication and QA testing for each of the major subsystems is described in this paper. The complete system will not be assembled and tested in the US. All components of the IVA are to be delivered as subassemblies to AWE in the UK in mid 2012 for assembly and commissioning.