Research On A 6-18GHz High Power Helix Traveling-Wave Tube

The helix traveling wave tube(TWT)has the characteristics of wide frequency band,high gain,and high power,and it plays an important role in the field of modern information military weaponry.Broadening the bandwidth and increasing the output power is the development direction of the helix TWTs.In this paper,the 6-18 GHz high-power helix TWT is researched,aiming to achieve high-power output in the double-octave range.In order to broaden the bandwidth,a helical slow-wave structure loaded with metal blocks in the support rods was designed,its high-frequency characteristics were studied,and the entire tube model was determined to analyze the injection-wave interaction.In addition,the corresponding input and output structure and periodic permanent magnet focusing system are designed.The main work of this paper is as follows:1.Use HFSS software to complete the design of the slow-wave structure(SWS)of the 6-18 GHz helix traveling wave tube.Some commonly used helical slow-wave structures are introduced.On this basis,a slow-wave structure loaded with metal blocks in the support rods is studied.Analyze the size of each parameter,study the influence of size parameters on high-frequency characteristics,and finally determine the structure size of the slow-wave structure.2.Carry out 6-18 GHz helix traveling wave tube beam-wave interaction simulation calculation.Because the designed helix traveling wave tube has a wide working bandwidth and requires high power output,in order to suppress the possible back wave oscillation and second harmonics,the final design of the whole tube structure is that the pitch and radius of the helix are gradually changed and jumped,and attenuation and truncation are added at suitable positions.Set the working parameters,such as the working voltage is 15.3KV,the working current is 2.1A,the channel radius is 0.67 mm,the electron injection filling ratio is 50%,etc,the simulation results show that,except for the 6GHz frequency point,all other frequency points obtain pulse power greater than5 k W,and at the low frequency band,the second harmonic is suppressed.3.Use the three-dimensional simulation software CST to design the input and output structure matching the helix traveling wave tube.For the 6-18 GHz helix traveling wave tube,the input structure adopts a coaxial structure,which includes two parts: coaxial impedance conversion and coaxial energy transmission window.The output structure adopts a coaxial-to-double-ridge waveguide structure,which also includes two parts,which are the output of the double-ridge waveguide and the energy-transmission window of the double-ridge waveguide.The results show that the designed energy transmission structure matches well with the slow-wave circuit.Finally,further simulation optimized the output structure of a 4-18 GHz helix traveling wave tube.4.Design cycle permanent magnet focusing system.According to relevant theoretical derivation,the required magnetic field peak value and period length of the PPM focusing system are calculated.Modeling and simulation are performed to verify the rationality of the designed periodic permanent magnet focusing system.