Conductivity and discharge guiding properties of mid-IR laser filaments
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The electric properties of mid-IR filaments in air have been investigated in comparison with their more traditional near-IR counterparts. Although the number of ions left after the pulse is similar for both spectral regions, filaments at 3.9 µm produce lower electron densities and lower-pressure depression, which prevent them in the present conditions (25 mJ, 90 fs) to trigger or guide HV discharges (130 kV over 12 cm). We conclude that mid-IR filaments require significantly higher energy/power levels than their near-IR counterparts for applications related to lightning control and for fully taking advantage of their unique propagation properties (single, large diameter filaments over long distances).
We acknowledge support from the ERC advanced Grant FILATMO and the technical support of M. Moret and C. Barreiro (University of Geneva). We also acknowledge the numerical simulations performed by N. Berti (University of Geneva). From the Austrian side, the research was supported by the Austrian Science Fund (FWF) through the grants NextLite PO3 (Project No. F4903-N23) and MIR Filament (Project No. P26658-N27)
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