Research On π Mode Coupling Double-gap Rectangular TM₃₁₀ Cavity Coaxial Line Output Circuit

The dissertation introduces the significance and the existent problem of research in high-order mode multi-beam klystron cavity output circuit to the point. Be based on it, we bring out the structure ofπmode coupling double-gap rectangular TM₃₁₀ cavity coaxial line output circuit.Adopting the method of simulating and calculating Isfel3D software to design, it can accurately calculate out each part's size of the filter. The designed structure of output circuit's resonance cavity is used 12 beams to work parallel connection. It works at X wave band. The Latin-Cross is used in the middle wall between two gaps and four big trapezium slots at the periphery in the coupling structure. Its working central frequency( f 0)is at 9720MHz. This coupling method not only maintains the axial electric field in the gaps, but also easily loads with the coaxial line. When it loaded with the coaxial line, the inductive electric current of the beams is easily educed from two sides of the coupling wall in the central of the cavity, and the axial electric field in the gaps still maintains uniform. Through the relationship of reflectance's phase with frequency, calculated the value of Qe, it is 22.8, the value of external quality factor is moderate. The comparative bandwidth of structure's output circuit surpasses 7%.At the process of simulating and designing the resonance cavity output circuit with coaxial line, because the distance of inductance pin to inner or outside diameter is too small, the maximum of electric field is at here, so the gap of which exists the danger of beating out. If the pin was made at the inner diameter, the slippage of pin is also inconvenient. And using the method of increasing a pin in the coupling orifice, then makes the two pins both drilled through the inner and outside diameter, the problem of beating out is solved, but near the frequency 8600MHz , there is a zero point difficult to eliminate, which is arose by 2πTM₂₁₀ model.For eliminating the zero point, we use other structures to simulate, although the zero point of some structures is eliminated, the two filters'central frequency is apart too much, the two wave crests are at a distance. For gaining the perfect result, it is need to do further research. For how to eliminate the zero point,to restrain the miscellaneous model, it is need to do further research and more search.Using the structure ofπmode coupling double-gap rectangular TM₃₁₀ cavity coaxial line output circuit, which is advantageous to maintain the axial electric field in the gaps of the cavity uniform,to improve the efficiency,bandwidth,output power and stability of the high-order model Multi-Beam Klystron.