The role of corona and space charges during femtosecond laser pulse filament guided high voltage discharges in air

Abstract

The plasma column left behind by ultrashort laser pulse filamentation is utilized to guide high voltage (HV) discharges in air. Many experiments have been carried out where the filament plasma is placed between two HV electrodes and a discharge is guided across the large gap (for example Ref [1]). Researchers still believe that one application could be potentially guiding lightning in the atmosphere, like a lightning rod, due to the longitudinal extent of the plasma ranging over several 10's of meters [2]. However lab experiments can only demonstrate discharges over a few meters. The reason for this is still not very clear due to the overall physics of the process not being fully understood. Here, we present experimental results in air on the role of space charges and corona during the filament guided HV discharge. Our conclusion is that the main driver of the breakdown is an enhancement of the corona between the electrodes and that the electric fields available limit the discharge distance achievable.