Benchmarking the Suitability of NovecTM 4710 for Application in Flux Compression Generators

An experimental study evaluated the feasibility of replacing traditional insulating gases such as SF <tex-math notation="LaTeX">_6</tex-math> with C <tex-math notation="LaTeX">_4</tex-math> F <tex-math notation="LaTeX">_7</tex-math> N (3M, Novec 4710) in flux compression generator (FCG) applications. Currently available data indicate that Novec 4710 could offer certain performance benefits over SF <tex-math notation="LaTeX">_6</tex-math> . However, the available literature is focused on low frequency (50–60 Hz) and dc at static pressures. To evaluate the performance of Novec 4710 under the pulsed dynamic pressure and temperature conditions found in an FCG, we report a performance comparison between three sets of identical FCGs using air, SF <tex-math notation="LaTeX">_6</tex-math> , and Novec 4710 as the insulating gas. The generators used in this study had a single stage, directly seeded design with an armature diameter of 25 mm and a stator diameter of 46 mm. To highlight the performance of the different gases rather than any wire insulation, the stator was constructed with uninsulated wire. Furthermore, the generators were seeded aggressively, making the performance difference between the different gases more apparent. The performance was monitored with a pair of differential Rogowski coils that captured the generators' di / dt while also using high-speed videography to capture possible gaseous breakdown signatures. The data gathered during this study indicate that Novec 4710 performs at least as well as SF <tex-math notation="LaTeX">_6</tex-math> in FCG applications, if not significantly better.