A study of sub-THz gyrotron drives
| Autor: | Li-jhen-li, 李麗珍 |
|---|---|
| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 The gyrotron backward-wave oscillator is a high-power oscillator that converts the energy of the electron beam into millimeter-wave by the frequency of the electron cyclotron and has a broadband regulation and a low operating voltage characteristic. However, due to its required external magnetic field is too high and the efficiency is too low, so that its practicality reduced. Therefore, this study discusses the large cyclotron radius of the gyrotron backward-wave oscillator, the use of high-order harmonic mechanism to reduce the required external magnetic field, and improve its output power. In addition to the characteristics and development of the gyrotron backward-wave oscillator, this paper includes the history of gyrotron development, nonlinear theory and boundary condition setting, program simulation and operation flow, mode selective circuits. And the oscillation characteristics of different harmonics are analyzed, including the relationship between the start-oscillation current and the applied magnetic field, and the influence of the output power and frequency on the applied magnetic field. We use the steady-state nonlinear program to analyze the results. It is found that the start-oscillation current of the TE_3,7^((3) ) mode with uniform structure is obviously increased with the decrease of the magnetic field, and the operating current is also increased,TE_2,5^((2) )、TE_5,11^((5) ) competition modes occur. Therefore, we use the non-uniform structure of the gyrotron backward-wave oscillator, but TE_3,7,2^((3) ) in the magnetic field range 103.7 ~ 105kG with the lowest start- oscillation current of 0.2 ~ 0.6A, may be with TE_3,7,1^((3) ) produces an axial competition pattern. Finally, we found TE_3,7,3^((3) ) mode, yields output power and frequency on the external magnetic field relationship, found that in TE_3,7,3^((3) ).The simulation results show that the maximum stable output power of TE_3,7,3^((3) ) gyrotron backward-wave oscillator is 4.0 ~ 5.5kW when the magnetic field is 103kG current is 0.6A. In order to make the TE_3,7,3^((3) )mode have low start- oscillation current and high oscillation power, the oscillator radius (Δr)、 magnetic field (ΔB) will be adjusted to increasee the inlet end radius, The simulation results show that the increase of the radius ∆r_w = 1.5×〖10〗^(-4)cm, the oscillation power of 4.0 ~ 5.6kW, adjustable frequency up to 0.4GHz; increase the ΔB =1.1 kG, the oscillation power up to 4.0~5.6 kW, adjustable frequency Up to 0.4GHz . |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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