Physics of Electric Discharges in Atmospheric Gases: An Informal Introduction

Abstract

Abstract.A short account of the physics of electrical discharges in gases is given from the viewpoint of its historical evolution and application to planetary atmospheres. As such it serves as an introduction to the papers on particular aspects of electric discharges contained in this issue, in particular in the chapters on lightning and the discharges which in the last two decades have been observed to take place in Earth's upper atmosphere. In addition to briefly reviewing the early history of gas discharge physics we discuss the main parameters affecting atmospheric discharges like collision frequency, mean free path and critical electric field strength. Any discharge current in the atmosphere is clearly carried only by electrons. Above the lower boundary of the mesosphere the electrons must be considered magnetized with the conductivity becoming a tensor. Moreover, the collisional mean free path in the upper atmosphere becomes relatively large which lowers the critical electric field there and more easily enables discharges than at lower altitudes. Finally we briefly mention the importance of such discharges as sources for wave emission.

Atmospheric Electrification in Dusty, Reactive Gases in the Solar System and Beyond

“…A long-standing question is how lightning can be initiated because the observed electric fields are below the classical breakdown field (where electron impact ionisation overcomes electron attachment to oxygen in the Earth's atmosphere; e.g., Treumann et al 2008;Helling et al 2013), and free electrons are not available anywhere in the atmosphere. Gurevich et al (1992) suggested that cosmic particle showers could supply free electrons and that relativistic run-away electron avalanches could develop in an electric field below the classical breakdown value.…”

Optical Investigations of N2 Atmospheric Pressure Plasma Jets

“…Cold plasmas have many advantages such as the effects of low temperature, low electric field, and the chemical interactions of the active radicals have various applications. Cold plasmas are widely used in many applications such as sterilization, surface applications such as coating, activation, cleaning, polymerization, oxidation, nitriding, and medical treatments [1][2][3][4]. Instead of noble gases such as argon (Ar), helium (He), etc., nitrogen (N2) gas has also used in these applications [5,6].…”

Observations of Stratosphere-Troposphere Coupling During Major Solar Eclipses from FORMOSAT-3/COSMIC Constellation

“…Solar eclipse also changes the ionosphere total electron density (Le et al 2009). Treumann et al (2008) described the physics of electric discharges in the atmospheric gases, and average altitude profiles of temperature and mass density from the surface to 150-km altitude.…”