Triggering and Guiding of High-voltage Tesla Coil Discharges by Femtosecond Laser-induced Plasma Filaments in Air

We report experimental guiding of high-voltage (HV) sparks discharges in air with plasma filaments generated by a terawatt femtosecond laser. Large sparks discharges are shoot up from a HV electrode fixed at the top of a Tesla coil voltage elevator to a farther grounded one. Ultrashort laser pulsed beams of energy on the order of the mJ through open air exhibit non-linear propagation effects. Indeed, long plasma filaments with electron density of 1010 cm can be generated as the result of a dynamical competition between non-linear Kerr self-focusing and plasma defocusing, which is caused by the laser field ionization of air. These plasma filaments with characteristic radii of about 100 μm are remotely generated and persist over long propagation distance. Such straight conductive plasma column can carry high current and high voltage in atmospheric air. The unique properties of plasma filaments make them ideally suitable for the triggering and guiding of HV discharges over long gaps.