Inception and growth of an electrodeless atmospheric double-headed streamer

Area of Science:

• Physics
• Atmospheric Electricity
• Plasma Physics

Background:

• Gas discharge physics aids the study of atmospheric electricity phenomena like lightning and sprite streamers.
• Double-headed streamers (DHS) observed in nature remain poorly understood, with prior research limited to theoretical and numerical models.

Purpose of the Study:

• To present the first experimental model of double-headed streamers (DHS).
• To investigate the formation mechanism and characteristics of DHS in a controlled laboratory setting.
• To validate theoretical predictions regarding DHS formation.

Main Methods:

• Utilized a ground-pressure plasma jet device with noble gas flow (helium or neon) expanding into ambient air.
• Observed the growth of positive and negative streamer heads originating from an isolated ionized column.
• Employed advanced diagnostics, including Stark effect measurements, to determine the electric field along the discharge axis.

Main Results:

• Successfully ignited and experimentally modeled double-headed streamers (DHS) in laboratory conditions.
• Confirmed that DHS growth originates from an isolated ionized column, supporting theoretical studies.
• Measured electric fields along the discharge axis using Stark effect, indicating DHS can form in subbreakdown conditions.
• Highlighted the critical role of the preionization phase in DHS ignition.

Conclusions:

• The experimental model provides direct evidence for DHS formation mechanisms.
• Findings align with theoretical and numerical studies, enhancing understanding of atmospheric electricity.
• This research opens avenues for further investigation into elementary processes governing electrical discharges in the atmosphere.