Investigations on Mode Transition Mechanisms and Discharge Characteristics of Electrically Exploding Aluminum Wires in Argon Gas

Electrically exploding wires (EEWs) are a promising method for nanoparticle preparation, and the size distribution of nanoparticles is significantly affected by ambient pressure. However, the influence of ambient pressure on EEW characteristics is still unclear, which brings incredible difficulties in parameter optimization for nanoparticle preparation. In this article, mode transition mechanisms and discharge characteristics of EEWs in argon gas were experimentally investigated. A mode transition of EEWs, from the shunting to the internal as ambient pressure increases, was demonstrated through electrical measurement. The ohmic heating duration, maximum power, and breakdown electric field increase with ambient pressure in shunting mode and show a saturated trend in internal mode. Through laser imaging and framing imaging, two typical structures of EEWs, that is, the “core-corona” structure ( $p < 50$ kPa) and the “discharge channel-vapor” structure ( $p >200$ kPa), were observed and analyzed. By reconstructing evolutionary trajectories of coronal plasmas and high-density cores, we have found that increased ambient pressure inhibits the diffusion processes of EEWs. According to ambient pressure, EEW in argon gas was divided into four regions: shunting, transitional, internal, and saturated.