Enhancement of energy deposition in the pulsed wire discharge for the synthesis of nanosized powders

Summary form only given, as follows. Various kinds of nanosized powders have been successfully synthesized by pulsed wire discharge, where a thin metal wire is exploded by a high-voltage high-current pulse. In general, the process of exploding wire is divided into metallic conductive state and plasma state. The plasma is generated from the Paschen breakdown of the gas desorbed and evaporated from the wire. When the plasma is formed around the wire, the energy deposited is strongly linuted because the electrical resistance of the plasma is relatively lower than that of molten metal wire. The energy deposited into the wire during metallic conductive state affects the amount of the liquid droplets generated from un-vaporized wire, and these liquid droplets resulted in micrometer-sized particles. Furthermore, when we synthesized compound powders by chemical reactions of metallic vapor with atmospheric gases, the liquid droplets became un-reacted metal particles, which decreased the purity of the compound powders. Therefore, enhancement of the energy deposition is important to remove micrometer-sized particles from the compound powders. In this research, Cu nanosized powders were synthesized by exploding copper wires of 0.25 mm in diameter and 25 mm in length in nitrogen gas at various discharge conditions.