Sprite discharges on Venus and Jupiter-like planets: a laboratory investigation

TL;DR

This study investigates sprite discharges on Venus and Jupiter-like planets through laboratory experiments, confirming scaling laws and analyzing morphological and spectral characteristics, revealing similarities and differences with Earth's sprites.

Contribution

It provides the first experimental confirmation of scaling laws for planetary sprites and characterizes their morphology and spectra in CO2-N2 and H2-He mixtures.

Findings

Sprite discharges are similar in morphology to Earth's but are fainter in visible light.

Spectra are dominated by N2 on Venus and show both species on Jupiter-like planets.

Spark spectra differ significantly from sprite spectra on Venus.

Abstract

Large sprite discharges at high atmospheric altitudes have been found to be physically similar to small streamer discharges in air at sea level density. Based on this understanding, we investigate possible sprite discharges on Venus or Jupiter-like planets through laboratory experiments on streamers in appropriate CO2-N2 and H2-He mixtures. First, the scaling laws are experimentally confirmed by varying the density of the planetary gasses. Then streamer diameters, velocities and overall morphology are investigated for sprites on Venus and Jupiter; they are quite similar to those on earth, but light emissions in the visible range are fainter by two orders of magnitude. The discharge spectra are measured; they are dominated by the minority species N2 on Venus, while signatures of both species are found on Jupiter-like planets. The spectrum of a fully developed spark on Venus is measured. We show that this spectrum is significantly different from the expected sprite spectrum.