Submicrosecond Spectroscopy of Lightning-Like Discharges: Exploring New Time Regimes

Geophys Res Lett. 2020 Aug 16;47(15):e2020GL088755. doi: 10.1029/2020GL088755. Epub 2020 Aug 7.

Abstract

Submicrosecond (0.476 μs per frame with an exposure time of 160 ns) high-resolution (0.38 nm) time-resolved spectra of laboratory-produced lightning-like electrical discharges have been recorded for the first time within the visible spectral range (645-665 nm). The spectra were recorded with the GrAnada LIghtning Ultrafast Spectrograph (GALIUS), a high-speed imaging spectrograph recently developed for lightning research in the IAA-CSIC. Unprecedented spectral time dynamics are explored for meter long laboratory electrical discharges produced with a 2.0 MV Marx generator. The maximum electron density and gas temperature measured in a timescale of ≤0.50 μs (160 ns) were, respectively, ≃1018 cm-3 and ≃32,000 K. Overpressure in the lightning-like plasma channel, black-body dynamics, and self-absorption in spectral lines were investigated.

Keywords: discharges; high‐speed; lightning; spectroscopy; temperature.