Nanomaterial synthesis via plasma ablation in suppressed electrical explosions of porous materials

Electrical explosion provides an ultrafast route to nanomaterials, but bulk vaporization, current restrike, and plasma instabilities often broaden the product size distribution. Cu wire, Cu foil, Cu foam, and C foam were compared at an initial stored energy of 250 J using electrical, optical, and electromagnetic diagnostics together with high-speed imaging. For Cu foam, the voltage peaked at 6.1 kV and 1.35 μs, compared with 31.9 kV and 3.78 μs for Cu wire. At this peak, only 17.6% of the complete-vaporization energy had been deposited, whereas 86.7% of the total deposited energy entered afterward. Asynchronous hotspots and the absence of an independent secondary high-frequency pulse support a mechanism in which weak connections in the porous network undergo local phase transition and ionization before bulk vaporization. The resulting plasma channels continuously ablate the condensed-state skeleton. Cu foam yielded a smaller mean particle size than Cu wire, 26.13 vs 72.39 nm, and a narrower distribution. C foam produced nanofibers with a mean diameter of 41.88 nm. X-ray diffraction showed prominent metallic Cu peaks for Cu foam products, whereas Cu wire and Cu foil products were characterized primarily by copper oxide peaks. Under the tested conditions, these results support suppressed bulk vaporization and sustained plasma ablation in foam loads, suggesting a route toward particle-size control and nanofiber formation.