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

We measured the electric charge release from single water microdroplets 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. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3220066]