Transmission Of RF Electromagnetic Energy By Femtosecond Laser Plasma Channels

The intense femtosecond laser pulses propagation in air induces a lot of interesting physical phenomena, such as filamentation. In this thesis, the properties of intense femtosecond laser pulses propagation in air and the properties of femtosecond laser filaments were analyzed. Based on the electric conductivity of femtosecond laser filaments, the femtosecond laser filaments act as virtual transmission lines and can be used for carrying energy in the form of radio frequency (RF) electromagnetic waves. Therefore, we discussed the interaction of RF electromagnetic wave with femtosecond laser-induced plasma filaments and the preliminary experiments were completed. The experimental results revealed that the femtosecond laser-plasma channel can induce violent changes in the electromagnetic field. The characteristics of guiding RF electromagnetic wave in three different structures of femtosecond laser-plasma channel transmission lines (single channel, parallel channels and plasma waveguide composed of a number of plasma filaments) were also studied and the different distribution of electromagnetic fields was obtained. Then, the attenuation of electromagnetic wave was calculated, and the calculations showed that RF electromagnetic power was increased compared to the free propagation of RF electromagnetic wave over a limited distance.