Test Results of the 7 OHM, 2.5 MV, Laser Triggered PFL for the HYDRUS IVA

A prototype PFL was tested in a test bed at L-3 as part of the recently completed IVA design effort for flash radiographic sources in the new Hydrus hydrodynamics research facility at AWE. The prototype PFL represented one of the ten PFLs in the baseline IVA configuration. The 7 ohm water filled, coaxial PFL incorporates a laser triggered output switch followed by a self-breaking water sharpening switch near the end of the output line to produce a 60 ns long pulse which rises in less than 10 ns. A pre-existing Marx was modified to charge the PFL to nominally 2.5MV in 1.5 micro-seconds to match the charge rate predicted for the full IVA circuit. In addition to the PFL hardware, the other parts of the IVA that were prototyped and tested included the Marx oil/oil diaphragm, a section of the multi-port, 50 ohm oil filled manifold, and the oil-filled input and output elbows. The PFL was tested up to 3MV in the prototype facility to accelerate the reliability tests. The performance and reliability test results for the PFL and oil filled lines based on >2730 shots are presented in this paper. The test results for the LTGS along with the switch type down-selection are presented separately at this conference. The empirically based reliability of the PFL and other components that were tested is compared to the goals set out by the formal availability, reliability, and maintainability (ARM) assessment for the whole IVA. The reliability calculations for the PFL utilize an equivalent number of nominal voltage shots to take into account the higher electrical stress of the over-voltage shots. The PFL output waveform is compared to the design prediction and circuit models that match the measured performance are presented. Problems and failures that were encountered during the course of testing are discussed along with their solutions, fixes, and mitigations.