THEORETICAL MODELING OF TERAHERTZ (THZ) RADIATION EMISSIONS FROM FREE ELECTRON LASER (FEL)

Abstract

The research in the subject of terahertz (THz) radiation has gained a great awareness since nineties to fill the THz gap in the electromagnetic spectra due to the existing significant properties and resulting applications in diverse areas such as medical, spectroscopy, communications and others. The non-ionizing and high penetration potential of the THz radiation has enabled numerous techniques involving both optics and electronics to be proposed to study the emission and detection of THz radiation. The thesis focuses on designing of analytical models to study the emission of high power THz radiation by employing premodulated electron beams using free electron laser (FEL) as a classical device. The role of premodulation of the beam in generation of the THz radiation is discussed. To study the efficient emission of the radiation, plasma based medium such as surface plasma wave, Langmuir wave are used as wigglers in FEL. Slow wave structure involving a waveguide with dielectric lining is also used as a Cerenkov FEL for THz emission. The power, amplitude and efficiency of the radiation wave are evaluated to have an analysis of the output radiation. We have studied the effect of parameters of the electron beam, wiggler, plasma and other factors affecting the tunability of the THz radiation. The route followed in the analytical treatment of the analysis involves fluid theory which deals with the interaction of premodulated electron beam, electromagnetic wave and a pump signal. The softwares used for obtaining the results are MATLAB and MATHEMATICA.