ROLE OF BEAM PRE-BUNCHING ON TERAHERTZ RADIATION EMISSIONS

Abstract

The advent of terahertz (1-10 THz) range in the field of Science and Technology has shown its remarkable potential. Terahertz radiation is characterized by an ample verity of applications in the field of domains such as Physics, Biology, Chemistry, Life science and Computer science. The terahertz range of electromagnetic radiation has very large potential applications in the field of hidden objects detection and medical imaging because it penetrates clothes and non-conducting materials. The unique property of THz radiation is non-ionising power and it is not harmful for the living tissues. The present Ph.D. dissertation describes the research involving the generation of terahertz radiation in plasmas using relativistic electron beam (REB). Consequently, it provides a good opportunity for developing miniature integrated, tunable and coherent radiation sources in THz frequency range at room temperatures. This research work is an effort to investigate the impact of beam pre bunching on THz radiation emissions, which allows us to see how the beam parameters and plasma parameters are affecting the output power of THz radiation emission. The broad outcome of the research is that the beam parameters such as beam energy, beam density and modulation factor are influencing the THz terahertz radiation emission. Additionally, the impact of plasma parameters such as electron plasma density and plasma density profile has been investigated in the present thesis. The present thesis includes the analysis of different plasma based micro structured schemes for THz radiation emission by employing planar iv semiconducting waveguides with double interface or a single interface, rippled density profile of plasma and upper hybrid wave wiggler. These schemes assure a stable, coherent and continuous terahertz sources for various applications. The methodology used for the compact models involve the interaction of pre-bunched electron beam with electromagnetic waves in THz frequency range. Moreover, the performance of the above mentioned models in the present thesis is verified with the existing results. In addition, the analytical and numerical calculations are performed using software MATLAB and the results are depicted graphically in 2-D and 3 D environment. Some of our theoretical findings are in compliance with the existing experimental observations.