CEDAR: Experimental Study of the Role of Secondary Electron Emission in Atmospheric Electricity

Electric discharges (commonly referred to as spark) occur naturally in lightning flashes, where it starts a simple electron avalanche process that elevates its temperature and energy leading to spectacular form. In the atmosphere, electric discharges manifest in various ways: glow coronae, St Elmo’s fires, diverse lightning discharges, Narrow Bipolar Events, upward-directed starters, blue jets, gigantic jets, red sprite and other Transient Luminous Events (TLEs). Most discharges start with a seeding electron avalanche, as in Townsend’s (1901) process, and can evolve into a glow, streamer, or leader discharge, or a combination of these. Two fundamental parameters that are central to avalanche mechanism are: (1) the effective Townsend ionization coefficient, which describes the well-known ionization of an atom or a molecule by electron impact; and (2) a poorly understood secondary electron emission coefficient, which is the object of this proposal. The research has many practical applications; for example, it is useful for (a) their role in lighting rod optimization; (b) disinfecting medical equipment, and (c) space systems going to Mars that encounter conditions that could trigger discharges. The main objective of the proposal is to advance the current understanding of atmospheric electricity on Earth and beyond. It will address the following scientific questions: (a) How does the secondary electron emission influence the ignition of electric discharges? (b) How does the electrode shape and composition impact the initiation of gas discharges? (c) How does dust change electrical discharges in Earth and Mars atmospheric conditions? The approach will utilize an existing dusty plasma chamber at the PI’s institution with new modifications to address the above questions and includes theoretical validation to characterize the initiation of dielectric breakdown in planetary atmospheres. The PI will also explore methods to promote scientific research in planetary sciences, geosciences, and astronomy by developing open access educational tools. This includes the creation of PyTHAGORA: Python Training for Heliophysics, Astronomy, and Geosciences: an Opencourse for Researchers with Applications. This proposal will support an early career, and several students at an emerging research institute. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.