Optical and illuminant characteristics of microsecond-pulse diffuse discharges in a point-to-point gap

Abstract

Diffuse discharge sustained by microsecond pulses can generate volume discharge at atmospheric pressure, which has been widely studied since 2010s. Although the fast rising time limits the formation of spark stream under certain condition in microsecond-pulse discharges, the pulse repetition rate and gap spacing may also affect the discharge mode. In this paper, the optical emission spectra and discharge images are investigated to analyze the optical and illuminant characteristics of microsecond-pulse discharge at different discharge modes. The emission spectra were used to analyze the optical characteristics of microsecond-pulse discharge. The experimental results showed that the emission spectrum of diffuse discharge ranged from 300 nm to 425 nm. Typical spectral lines, such as OH, N 2 , N 2 +, are observed. The emission spectrum of spark discharge ranged from 200 nm to 1000 nm. The spectral lines included NO, OH, N 2 , N 2 + and O, among which the spectral lines at 777.1 nm had the largest intensity, indicated the existence of oxygen species in spark mode. Furthermore, the grey-scale image was used to estimate the illuminant characteristics of different discharge modes in microsecond-pulse discharges. The maximum grey-level values were 60, 180 and 255 when the discharge modes were corona, diffuse and spark, respectively.