Collaborative Research: Corona Discharge in Electrified Storms Initiated by Particle-Laden Atmospheric Turbulence

Lightning is the most well-known component of the electrical nature of Earth’s atmosphere, but other electrical processes are critical to the composition of the atmosphere. Corona discharges are significant contributors to the development of the hydroxyl radical, which is a compound that reacts with many pollutants and has an important role in eliminating atmospheric methane and ozone. This study will investigate the role of turbulence in the development of corona discharges inside of clouds by performing controlled laboratory experiments. Beyond the implications for lightning and pollution, corona discharges are impactful in industrial manufacturing and relevant for future planetary science missions. The research team plans to test the key hypothesis that turbulence brings inertial particles carrying opposite charges together and causes significant local field enhancement, which exceeds the breakdown limit and initiates both subvisible corona and visible discharges. The primary mechanism to address this hypothesis is through controlled laboratory experiments using a Homogeneous and Isotropic Turbulence (HIT) chamber. The chamber is a cubic box with a side length of 1 meter and made of transparent acrylic panels allowing for the use of optical instruments. The research team will be able to control the turbulence, external electric field, and the droplet concentration, charges, and diameter. Measurements will include particle motion by particle image velocimetry, particle electric fields by field mill sensors, and discharge location and intensity by ultraviolet (UV) cameras. The data will be used to answer questions about how the multiscale electric fields develop and intensify in particle-laden turbulence and what the intrinsic connection is between the fluctuating electric field and the occurrence of visible and subvisible discharges. 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.