High Throughput Initiation Threshold Characterization of BNFF

Understanding early chemical reaction steps in detonation environments is critical to the development of robust detonation theories and non-phenomenological models. Towards this end, we present initiation studies of 3,4-bis(3-nitrofurazan-4-yl)furoxan (BNFF), a hydrogen-free explosive with the formula C₆N₈O₈. BNFF is of interest for its unique chemistry, high detonation temperature, and the subsequent formation of nanoscale carbon structures upon detonation. These studies are performed on Sandia’s High Throughput Initiation experiment, using laser-driven flyer plates to rapidly investigate the initiation threshold of vapor deposited BNFF samples as a function of thickness using photon doppler velocimetry (PDV) diagnostics. Initial cut-back style experiments, where the thickness of the sample is systematically reduced in order to monitor the progress of a reaction at various distances into the explosive, indicate that BNFF cannot build to a detonation at a depth of 25 µm up to an impact velocity of approximately 4200 m/s using a 25 µm thick parylene-C impactor. When given a greater depth of for reactions to evolve, we begin to see a build-up toward detonation. A sharp transition between detonation and sub-detonation behavior occurs in 100 and 150 µm thick films. This transition can be seen across a difference in initial impulse of approximately 100 m/s. Future work will involve incorporation of streak emission spectroscopy into the HTI platform to further elucidate initial chemistry.