Contribution of water droplets to charge release by laser filaments in air

Abstract

We measured the electric charge release from single watermicrodroplets illuminated by ultrashort laser filaments in air. This charge is up to 600 times larger than from a comparable filament volume in air. In contrast, for atmospheric droplet concentrations and sizes, the volume-averaged overall droplet contribution to the charge is small as compared with that of the filaments along its whole propagation path

Production of ozone and nitrogen oxides by laser filamentation

“…In parallel with the concentration of trace gases, we measured the relative efficiency of charge release by the filaments, as detailed in Ref. 19. Figure 2 displays the generation rate per unit volume of O 3 , NO, and NO 2 in the filament as a function of the incoming pulse energy and duration.…”

Influence of pulse duration, energy, and focusing on laser-assisted water condensation

“…Note that the ionization of the condensed particles contributes negligibly to the total charge. 10 In the considered atmospheric conditions, the incident polarization has little influence, if any, on the laser-assisted condensation process ͑Fig. 3͒ within the uncertainty of the measurement: The difference between the linear and circular polarization is not statistically significant ͑within ␣ Յ 0.025͒ for any size class.…”

“…Cross-check measurements using a condensation particle counter ͑TSI Model 3007, TSI Incorporated, Minnesota͒ allowed us to ensure that this measurement is free from artifacts due, e.g., to the electric charge deposed by the filaments on the particles. 10 Simultaneously, the measurement of the shockwave by a sonometric setup described in detail before provided an estimation of the ionization of the air. 11 When relevant, the statistical significance of the difference between experimental conditions was assessed by performing a Stu- dent test providing the risk ␣ that the two results are due to Gaussian sampling fluctuations.…”

Mid-infrared laser filamentation in molecular gases

“…The longitudinal plasma distribution in the filament was characterized with two electrodes spaced by 1 cm and biased at 500 V, movable inside the cell. The current flowing between the electrodes is proportional to the electron density [15].…”