WeiFeng Peng

Accurate large signal analysis of a wideband helix TWT using Beam Wave Interaction Simulator

Using Beam Wave Interaction Simulator (BWIS), one module of Microwave Tube Simulator Suite (MTSS), a wideband helix TWT has been accurately simulated. The slow-wave circuit parameters are calculated by High Frequency Circuit Simulator.

High Frequency Circuit Simulator based on finite integration technology

This paper provides the design and realization of high frequency circuit simulator (HFCS) which is based on the Finite Integration Technology. For vilification, the cold-test characteristics of two actual helical slow wave structures have been calculated and the results were found to be consistent with those of MAFIA simulation with same mesh density.

Recent advances of MICROWAVE TUBE SIMULATOR SUITE

Microwave tube simulator suite (MTSS) is a fully featured software package for microwave tube analysis and design. it consists of four modules now, microwave tube design environment (MTDE), electron optics simulator (EOS), high frequency circuit simulator (HFCS), and beam-wave interaction simulator (BWIS).

Application and validation of Microwave Tube Simulator Suite

Microwave Tube Simulator Suite (MTSS) is a full-featured software package for microwave tube analysis and design. It has been developed by University of Electronic Science and Technology of China (UESTC) and validated against some helix traveling wave tubes.

DIGITIZED NONLINEAR BEAM AND WAVE INTERACTION THEORY OF TRAVELING WAVE TUBE AMPLIFIERS

To simulate the beam and wave interaction (BWI) of various types of traveling wave tube ampliflers (TWTAs), a digitized nonlinear theory has been developed with two features. First, the digitized RF fleld proflles obtained from electromagnetic simulation software are applied to replace the analytical RF fleld proflles in TWTAs. Second, the relationship of energy conservation between the beam and RF flelds is used to derive the RF fleld equations. Based on this nonlinear theory, one-dimensional (1-D) code has been constructed to predict the performances of TWTAs. Comparisons between the simulations and the experimental results for three types of TWTAs, i.e., a K-band helix TWTA, a V-band coupled cavity (CC) TWTA and a W-band folded waveguide (FWG) TWTA, are discussed to prove this nonlinear theory.

A three-dimensional nonlinear beam–wave interaction theory for common traveling wave tubes

A three-dimensional (3-D) nonlinear theory model of beam–wave interaction for common traveling wave tubes (TWTs) is described. The equation governing the amplitude of electromagnetic wave is derived analogously to Poynting’s theorem. The electron dynamics are treated using the 3-D Lorentz force equations. RF space charge fields are obtained from solutions of the Helmholtz equations. In the model, the RF field profiles for cold structure are represented by the digitized RF field calculated by a finite-element software, HFSS. Because the digitized RF field can be obtained in the same way, the 3-D simulation code can be used to simulate common TWTs, such as helix TWTs, coupled-cavity TWTs, and even the folded waveguide TWTs. Results from the 3-D code are compared with those from 1-D code, experiment and the existing analytical theories for three types of slow wave structures.

A 3D simulation code for folded waveguide traveling wave tubes

A three-dimensional (3-D) large signal model of beam-wave interaction in a folded waveguide (FW) slow wave circuit is described. The 3-D code carries out with numerical solutions of the structure, without using the analytical formulations of the eigenmodes. This model can also be used in helix TWTs and coupled-cavity TWTs.

Impedance calculation of helical slow-wave structure using HFCS-I and MAFIA

Using HFCS-I and MAFIA, the impedance characteristics of a typical helical slow-wave structure (SWS) is studied, in which the Non-Resonant Perturbation (NRP) Method is adopted and the direct calculation from discrete Electromagnetic (EM) fields is performed. The results from HFCS-I and MAFIA are found to be consistent.

Recent developments on generalized large signal models for TWTs

We describe two large signal models of coupled-cavity traveling-wave tubes (CCTWTs) and folded-waveguide traveling-wave tubes (FWTWTs). These models include a generic theory derived from the Poyntings theorem and an equivalent circuit that uses a three-port network representation of the unit cell of the slow wave structures. Both of the models use the digital RF fields obtained from a 3-D finite element code, HFSS. The corresponding codes are applied to simulate the beam-wave interactions in a CCTWT and a FWTWT.

A nonlinear time-dependent simulation for helix traveling wave tubes

A one dimensional nonlinear time-dependent theory for helix traveling wave tubes in beam-wave interaction is studied. A generalized electromagnetic field is applied to the expression of radio frequency field. The substitution of a spatial average over a wavelength for a time average over a wave period is used in the equation of radio frequency field. The space charge field of electron beam is treated by space charge wave model in company with the space charge coefficient. The effect of radio frequency field and space charge field to electrons is processed by the equations of the electrons energy and phase. A simulating result of the time-dependent model is given.