Optical emission and quenching process of a Cu wire explosion: a spectroscopy study

This paper deals with an experimental study of a copper wire explosion in air and water at atmospheric pressure. The influence of the stored energy, discharge type, ambient medium on the electrical and optical characteristics of a single wire explosion was examined and clarified. Particularly, optical emission spectroscopy as well as self-emission image diagnosis were conducted to understand the radiant and quenching process of the explosion. The results revealed that the radiation mainly contained two stages: a white light (continuous spectrum) flash soon after the moment of explosion, and a long period of line radiation of Cu ions/atoms in the following dozens of microseconds. By analysing characteristic lines, Cu2+ was found in the very early stage of the expansion of the discharge channel (DC). Besides, obvious line radiation of O and N ions/atoms was found when there existed a current pause. As for plasma parameters, the Boltzmann plot method indicated that the average temperature of explosion products was similar to 1 eV, while the electron density experienced an apparent attenuation as the expansion of DC. In addition to this, the optical emission in air and water followed two distinctly different patterns, relating to the expansion of DC and diffusion of the ambient medium.