Microwave diagnostics of pulsed atmospheric discharge with electrolytic electrode and long-lived luminous formation in its afterglow

Abstract

The Gatchina discharge phenomenon holds significant promise as a laboratory model for simulating ball lightning. However, crucial aspects concerning the plasma components of the resulting afterglow remain unresolved. Notably, the measurement of the electron density, a critical parameter, has not been fully achieved thus far. In this study, microwave diagnostics and video recording were employed during a pulsed Gatchina discharge, along with synchronous measurement of discharge current and voltage. Distinct antennas were positioned at different heights to enable separate diagnosis of the discharge and the ensuing long-lived afterglow. The findings revealed that during the active phase of the Gatchina discharge, the plasma density was substantial enough to cause reflection of an electromagnetic wave with a frequency of 20 GHz from this highly conductive object. In the afterglow, the signal experienced only a moderate weakening of 10–20 percent, facilitating the determination of the time dependence of average electron density during the afterglow's passage between the two antennas. These measurements verified the unusually slow plasma decay in the afterglow of the Gatchina discharge, suggesting the potential significance of chemi-ionisation processes involving long-lived (metastable) particles.