Em Radiation From Femtosecond Laser Plasma Filaments And Attachment Of Rf Em Wave To The Filaments

The mechanism for femtosecond laser filamentation in air is the balance between Kerr self-focusing and plasma defocusing. It is a complicated nonlinear phenomenon, accompanying multiphoton ionization, group velocity dispersion, atmospheric diffraction and some other physics processes. In the thesis, the electromagnetic radiation from the femtosecond laser filament and the coupling of radio frequency electromagnetic wave to femtosecond laser plasma channel were studied.Firstly, in theory the frequency of the electromagnetic radiation from the plasma channel is below the plasma frequency. Then the corresponding experiments were carried out, in the direction perpendicular to the plasma channel the electromagnetic radiation with the range of EM frequency from8GHz to10.5GHz was observed, and the electromagnetic wave power is about100pW.Secondly, based on the electric conductivity of the plasma channel, in theory the characteristics of coupling RF electromagnetic wave to single filament was studied, and single filament can carry RF electromagnetic wave in the form of surface wave, but the attenuation coefficient is high. In the experiment, the interaction of RF frequency electromagnetic wave with filaments was studied, and the effect of laser intensity, the focal length and RF frequency electromagnetic wave power on coupling of RF frequency electromagnetic wave to single filament was studied, which is the basis of guiding EM wave by two filaments.Finally, RF frequency EM waves diagnostics of femtosecond laser plasma channels is proposed, and a new method of the plasma channel research is coming to us.