Local enhancement of atmospheric electrical field by long laser spark

A local atmospheric electrical field enhancement at polarization of a long laser spark (LLS) is considered. The analysis is made on the basis of LLS model, that connects the parameters of a real discrete LLS and specific conductivity of homogeneous LLS model of the same length and width. The magnitude of generated field can reach tens or hundreds kV/n˜m. It is dependent on the efficient specific conductivity of the LLS, i.e., mainly on density and power of the discrete spark centers, and on geometrical parameters like a length and width of LLS. It is shown, that two physical phenomena are responsible for restriction of a maximum in the enhanced field value. These two phenomena represent expansion of a spatial electric charge, which is taken out to the LLS ends during polarization, and excitation of the ionization wave, when an electric field exceeds ~30 kV/n˜m. At the negative end of LLS, where the electrons are taken out, the field is enhanced weakly and usually it does not exceed 30 kV/n˜m