Lei Wenqiang

Development of D-band continuous-wave folded waveguide traveling-wave tube

As Terahertz communication technology developed, the research for D-band folded waveguide Traveling Wave Tube (FWTWT) has become increasingly important. The design and simulation on the FWTWT was presented, including electron-optical system, Folded Waveguide Slow Wave Structure (FW SWS) and sapphire pill-box window. A prototype tube has been fabricated successfully through manufacturing processing study. In the work duty 100% experiment conditions, the electron transmission ratio is 97%. The continuous wave output power is 7.3W and the center frequency is 140.3GHz. The gain is 25.3dB and 3dB bandwidth is 3GHz.

Application and validation of the TWTCAD integrated framework

TWTCAD integrated framework is a suite of helix TWT design software. It is composed of five software and interface specification between software. It includes: FemGun, a 2D gun software based on finite element method; HelixCT, a 2D helix circuit cold test software; BWI, 1D & 2D & 3D large signal software; MDCollector, a 2D multistage depressed collector design software; fPPM, magnet design software. It has been validated against some TWTs and applied in microwave tube industry.

Dispersion Analysis of helical corrugation waveguide for Gyro-TWT and Gyro-BWO

The paper puts forward a simple method of solving the coupled coefficient and the dispersion equation of the backward wave in the helical corrugation waveguide gyro-BWO. And using the VBA macro in the software CST, two taper parts and a regular part helical waveguide is founded. A simulation method is used to analysis the dispersion curve.

Three-dimensional simulation of 14-vanes 5.8GHz strapped magnetron

The performance of 14-vanes 5.8GHz strapped magnetron is modeled, including cathode, vane, straps, pole pieces and output antenna using three-dimensional electromagnetic simulation code. The electric field distribution in the cold cavity simulation and the formation of the seven electron spokes confirm the π mode work in the oscillation cavity region. The output frequency 5.787GHz and output power 5.4kW in the hot test simulation is obtained in the uniform magnetic field distribution condition. The magnetron with an efficiency of 60% is operated at the beam voltage 4.5kV, the anode current 2.0A when the external axial magnetic field of 0.235T is applied. The simulation values by Fourier transformation of the voltage signal show a good output frequency spectrum.

Amplification simulation for Ka-band second-harmonic Gyro-TWT using a helical corrugation waveguide

The eigenwave dispersion of 8mm 3-folded helical corrugation waveguide is simulated using CST software. The electron beam 80kV and main magnetic field 0.67T are given by the eigenwave dispersion for Ka-band Gyro-TWT using helical waveguide. The beam-wave interaction procedure is simulated using a PIC code, in which TE11 and TE21 coupling mode transform and a right-rotating large-orbit electron bunch are obtained. The maximal output power is about 42.5kW and the maximal gain is about 29.3dB in 35GHz. The 3dB bandwidth is about 8.7% from 33GHz to 35.8GHz.

Controlling the cathode current for Performance influence of Oven Magnetrons

To reduce spectrum noise of magnetron, the method controlling the cathode current emission is referred by the three dimensional PIC code. Compared three cathode emission model of PIC code in the current control, the beam model is adapts for changing the current. In the appropriate emission current, the spectrum noise can be suppressed.