Investigation Of Klystron Asymmetric Double-gap Output Cavities And Output Circuit

This Master's Thesis provides an overview of klystron output circuit of the significance and problems, and on this basis, on the one hand, we proposed cylindrical resonator structure in asymmetric coupled double-gap working in model TM010, and at the same time, we give the precisely relation of Electric field strength and gap distance aboutπ-mode and 2π-mode by using Isfe13D simulation software in under the conditions of 1.25GHz,3GHz and 5GHz. And we make a further particle simulation study with the MAGIC; On the other hand, working in the TM310 cylindrical cavity coupled rectangular waveguide output circuit was studied.We make the electromagnetic software simulation to the non-symmetry double-gap cavities at the center frequency of 1.25GHz,3.00GHz,5GHz, and obtain the relations that when the two gap width, for theπmode, the two gap induced electric fields almost equal size and for the 2π-mode, two gap induced voltages almost equal the size. We also use the equivalent circuit theory through analysis the cavity gap voltages, and the results obtained are consistent with the software simulation results. Secondly, according to the distribution of electromagnetic field inside the cavity, one-dimensional analysis of the issues is used, and using the kinetic theory, we get the formula of the best output power corresponding to the two best gap width and gap length of drift tube in asymmetric double-gap output cavity by theoretical calculations. When the electron beam acceleration voltage V0= 30kv, electron beam current I= 30A, center frequency f=3.00GHz, focusing magnetic field B 0.6TASLA, we confirm that the double-gap non-symmetric cavity klystron output power can be improved more than the double-gap symmetry cavity through particle simulation to the gap symmetry and non-symmetrical situation, Finally, a kind of multi-beam klystron, working in high-order mode TM310 cylindrical cavity coupled rectangular waveguide output circuit is designed in this paper. The work center frequency is 7585.3MHz. The drift tube gap characteristics impedances are calculated and the output bandwidth of the output circuit is analyzed. The results show that using a cylindrical TM310 mode in the same frequency condition, the volume of the cavity is less 6 times than the volume of cylindrical resonator TM010 mode; Each drift tube characteristic impedance after TM310 cylindrical cavity coupling rectangular waveguide changes slightly compared with that before, but they are very close to the before. We calculate the output cavity external quality factor with the Reflection coefficient phase method and the Equivalent circuit method 154 and 160, respectively. The output center frequency 7585.3MHz, is lower 26.5MHz than the cavity resonance frequency before coupling, and the output bandwidth is about 3%, so the type of Output circuit is more suitable for high frequency narrow-band multi-beam klystron section.