Plasma dynamics of a laser filamentation-guided spark

Abstract

We investigate experimentally the plasma dynamics of a centimeter-scale, laser filamentation-guided spark discharge. Using electrical and optical diagnostics to study monopolar discharges with varying current pulses we show that plasma decay is dominated by free electron recombination if the current decay time is shorter than the recombination characteristic time. In the opposite case, the plasma electron density closely follows the current evolution. We demonstrate that this criterion holds true in the case of damped AC sparks, and that alternative current is the best option to achieve a long plasma lifetime for a given peak current.

Long-lived laser-induced arc discharges for energy channeling applications

“…Interestingly, while the measurements performed at times corresponding to a local current extremum yield electron profiles, the electron density falls below the detection threshold when the current is near 0. It means that electron density starts to oscillate at twice the current frequency, as it was predicted in the case of a low frequency AC discharge current 35 .…”

“…We have previously shown that the temporal evolution of electron density in filamentation-guided discharges is dictated by the discharge current waveform when the current time evolution is slow 35 . From this finding we devised two different techniques to increase the plasma lifetime to a millisecond timescale, that we demonstrate in this Article: If a high electron density plasma is required, an oscillating current with high amplitude and low damping is best adapted.…”

Shockwave-assisted laser filament conductivity

“…However, the electric field before the lightning initiation is close to DC. In this regime, new behaviors like discharge suppression and remote spark-free unloading [24,25] or an increase of the plasma lifetime in a coupled AC-DC configuration [26,27] have been observed.…”

Dynamics of the femtosecond laser-triggered spark gap

“…Femtosecond filament triggered HV discharges have been widely studied in recent years, with applications envisioned to include reconfigurable RF antennas and guiding of electrical pulsed power, including lightning [23][24][25][26][27][28].…”