Stage-Resolved Spectral Research for Intermediate-Frequency Vacuum Arcs

To determine the plasma parameters of an intermediate-frequency (IF) vacuum arc, a staged spectroscopy experimental system for the IF vacuum arc is established. Stage-resolved spectra of 7 kA IF vacuum arcs at 360 and 800Hz were obtained across the 180–1180-nm wavelength range under this experimental platform, with arc evolution divided into as three distinct stages: ignition, burning, and extinction. The Boltzmann plot method was employed to analyze the spectra across different frequencies and stages. This revealed the evolution of electron density and temperature throughout the stages, along with frequency-dependent effects on plasma parameters and thedegree of local thermodynamic equilibrium (LTE). By correlating arc morphological imagery with arc voltage/current waveforms, we analyzed the characteristic development patterns of IF vacuum arcs and evaluated the combined influence of these morphological features and LTE conditions on electron density.