Ultrashort pulsed laser atmospheric filament properties and microwave radiation inferred from S-band guided wave interaction and self-emission
Abstract
The electrical conductivity σ of the plasma filament left behind by an ultrashort pulsed laser (USPL) optical pulse after it is geometrically then self-focused in air via the Kerr effect is measured by attenuation of a 3.2 GHz TE10 mode within an S-band waveguide through which the filament passes, taking into account the characteristic radius R of the filament, as determined by fast camera visible light imaging. Models of the major air constituents' ionization rate Wi vs. local laser intensity I, and of electron temperature T and mean axial electron momentum $\left\langle p_{z}\right\rangle $ vs. peak laser intensity I0 are then used to infer a hypothetical steady state filament's I0, T, major species particle densities, and assumed axially invariant current time integral Q and current decay rate ν after pulse passage. Q is independently measured via the filament's self-emission signal in the waveguide for comparison. The theoretical far field microwave radiation pattern due to the actual axial variation in $Q=Q\left( z\right) $ is compared favorably to published measurements. A much lower upper bound on ν is inferred once such radiation is taken into account. Results are presented along a $30$~cm long filament at a broad range of atmospheric pressures.
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BibTeX
@misc{ruden2026ultrashort,
title = {{Ultrashort pulsed laser atmospheric filament properties and microwave radiation inferred from S-band guided wave interaction and self-emission}},
author = {Edward. L. Ruden and James. E. Wymer and Jennifer. A. Elle and Alex C. Englesbe and Andrian P. Lucero and Erin A. Thornton and Andreas Schmitt-Sody},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.10852},
eprint = {2607.10852},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.10852},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Ultrashort pulsed laser atmospheric filament properties and microwave radiation inferred from S-band guided wave interaction and self-emission
AU - Edward. L. Ruden
AU - James. E. Wymer
AU - Jennifer. A. Elle
AU - Alex C. Englesbe
AU - Andrian P. Lucero
AU - Erin A. Thornton
AU - Andreas Schmitt-Sody
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2607.10852
UR - https://arxiv.org/abs/2607.10852
AB - The electrical conductivity σ of the plasma filament left behind by an ultrashort pulsed laser (USPL) optical pulse after it is geometrically then self-focused in air via the Kerr effect is measured by attenuation of a 3.2 GHz TE_10 mode within an S-band waveguide through which the filament passes, taking into account the characteristic radius R of the filament, as determined by fast camera visible light imaging. Models of the major air constituents' ionization rate W_i vs. local laser intensity I, and of electron temperature T and mean axial electron momentum $\left\langle p_{z}\right\rangle $ vs. peak laser intensity I_0 are then used to infer a hypothetical steady state filament's I_0, T, major species particle densities, and assumed axially invariant current time integral Q and current decay rate ν after pulse passage. Q is independently measured via the filament's self-emission signal in the waveguide for comparison. The theoretical far field microwave radiation pattern due to the actual axial variation in $Q=Q\left( z\right) $ is compared favorably to published measurements. A much lower upper bound on ν is inferred once such radiation is taken into account. Results are presented along a $30$~cm long filament at a broad range of atmospheric pressures.
ER -