Two Dimensional Distribution of Metallic (Cu) Vapor in a Forced Vacuum Arc Extinction by LIF

Abstract

It is important to observe the metallic vapor dissipation after interrupting a vacuum arc, for getting a deeper understanding of dielectric recovery processes, especially for DC interruptions. The object of this paper is to obtain two dimensional density distribution of copper vapor in a forced vacuum arc extinction. The method of laser-induced fluorescence (LIF) using a pulse laser with a central wavelength at 324.8 nm was adopted here. Meanwhile, an ICCD was used to capture the 510.6 nm fluorescence signal with an exposure time of 50 ns. The fluorescence can be distinguished from $125\mu\mathrm{s}$ (the moment of arc extinction) to $375\mu\mathrm{s}$ with a time interval of $25\mu\mathrm{s}$ . As a result, we could obtain the relative density distribution of ground-state copper metal vapor after the arc extinction. The results show that on the condition of CuCr25 contacts the metal vapor was evenly distributed in the gap and rapidly spread over time. The density of the copper vapor between the contacts dropped to less than 10% of the initial stage $200\mu\mathrm{s}$ after arc extinction. On the contrary, on the condition of CuCr50, higher copper metal vapor density at the moment of arc extinction was observed. It seems that the higher Cr content in the Cu-Cr contacts will lead to producing more metal vapor around current zero.