| Due to simple structure and ease processing the double planar transmission line is an important functional device in THz band. Slow-wave structure based on dual-plate waveguide has been applied to Terahertz backward wave oscillator and waveguide switch in the vacuum electronic learning.In this dissertation, with the theoretical analysis and simulation, the dispersion characteristics of the plasma loaded double planar slow wave structure are studied. The main works are the following:1. The modes of transmission in double plate transmission line are analyzed. The field distribution map of several low-level mode such as TEm and TMm are given by comsol3.5a. The simulated results show good agreement with the HFSS calculation result.2. The dispersion relation of the dielectric loaded double planar rectangular grating slow wave structure is derived by mode-matching method. The dispersion curve of a few low order modes of the odd mode and even mode are presented by the numerical method. The influence of structural parameters (period length, slot width, groove depth and metal column gap), isotropic media and anisotropic media are analyzed.3. The dispersion characteristics of the non-magnetized plasma loaded double planar rectangular grating slow wave structure are analyzed. With the increase of plasma density dispersion curve is shifted upward significantly. Because the shift speed of the lower cutoff frequency for TM mode is greater than that of the upper cut-off frequency bandpass frequency range reduced gradually and the dispersion curves become flattened.4. The dispersion characteristics of the magnetic plasma loaded double planar rectangular grating slow wave structure are studied. For two cases including the magnetic field parallel and perpendicular to the direction of propagation external magnetic field affects the dispersion characteristics of TM mode. The results indicate, in the magnetic field parallel to the direction of propagation and the same plasma density, dispersion curves of TM mode as a whole produce a certain frequency shift with the increase of magnetic field. In the magnetic field perpendicular to the direction of propagation and the same plasma density, frequency shift range of TM mode dispersion curve is greater than that of the magnetic field parallel to the direction of propagation significantly. Physical mechanism is that location of the strongest electric field of the TM mode is exactly perpendicular to direction of external magnetic field due to magnetic field perpendicular to the direction of propagation E×B field has a greater impact on electrons in plasma. The dispersion characteristics of the transmission wave undergone significant changes. Using the above characteristics, change of magnetic field and plasma density may control the propagation characteristics of terahertz wave. |
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