JianQing Li

Recent Developments to the Microwave Tube Simulator Suite

Recent developments to microwave tube simulator suite (MTSS) are reported in this paper. The MTSS is a full-featured tightly integrated software package for microwave tube analysis and design. It includes a commercial grade user interface and three physics simulators. The electron optics simulator is a finite-element (FE) 2-D and 3-D electrostatic steady-state beam trajectory code that has been used to design beam optics, including electron gun and collector. High-frequency circuit simulator is a full 3-D FE computational electromagnetic code that aims to get the accurate electromagnetic wave character spreading in high-frequency structures, such as dispersion, coupling impedance, and attenuation. Beam wave interaction simulator is a large-signal simulation code for helix traveling wave tubes (TWTs), coupled-cavity TWTs, and klystrons. The first version of MTSS was released in 2007, and all of these three physics simulators and user interface are improved and updated over the past six years. This paper reports on some significant advances to MTSS; new Ribbon style user interface, a lot of component modeling templates, more abundant postprocessing features, parallel version, full 64-bit version, more physics, and computation methods improvement.

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.

Accurate and Fast Finite-Element Modeling of Attenuation in Slow-Wave Structures for Traveling-Wave Tubes

This paper presents a novel 3-D finite-element modeling technique for the arbitrary lossy slow-wave structure (SWS) of a traveling-wave tube (TWT). By using this technique, we can accurately and quickly calculate not only dielectric losses but also conductivity losses of the SWS. In this modeling technique, a new frequency-specified eigenmode analysis (FSEA) for SWSs is proposed and utilized. Unlike the traditional phase-advance-specified eigenmode analysis for SWSs, which has to solve a nonlinear generalized eigenvalue problem (GEP), the new FSEA approach only needs to solve a linear GEP and is capable of obtaining the attenuation constant more accurately and directly without any postprocessing when simulating the lossy SWSs. Moreover, to further significantly improve the efficiency of modeling lossy SWSs, three advanced techniques are introduced in the standard implicit restarted Arnoldi method (IRAM) and an improved inexact IRAM is proposed. By simulating many practical SWSs, the accuracy and highly efficient performance of this modeling technique have been validated. It is shown that this modeling technique would be very useful to design a low-loss SWS for high-efficiency TWTs.

A Novel Approach of Removing Spurious DC Modes in Finite-Element Solution for Modeling Microwave Tubes

A convenient and efficient approach for removing the spurious dc modes in finite-element solutions for modeling microwave tubes is proposed. This method is based on higher-order hierarchical-basis functions and is able to deal with both standard and rotated periodic boundary conditions. The application of this approach results in a robust, accurate, and efficient eigensolver for slow-wave structures, which significantly reduces the required memory and computational time.

Microwave Tube Simulator Suite-Part I: Architecture and Feature

Microwave tube simulator suite (MTSS), tools for microwave tube design, is developed by Theory and Computer Simulation Lab. of University of Electronic Science and Technology of China. 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).

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).

A 3-D Large-Signal Model of Folded-Waveguide TWTs

A steady-state 3-D large-signal model of the beam-wave interaction (BWI) in folded-waveguide (FW) traveling-wave tubes (TWTs) has been developed. The model used a three-port network representation of the circuit and a set of discrete rays representation of the 3-D electron beam. Values of the impedance elements that characterize the model are determined by a 3-D finite-element code, high-frequency circuit simulator (HFCS). Besides, the RF fields inside the beam tunnel are represented with the digitized field profile obtained from HFCS. A new circuit attenuation model is described by introducing only one parameter. The model has been implemented in the BWISFW-3-D code. The results of the code predictions agree well with the measured data for an FW-TWT operating in the W-band. The effect of uniform focusing magnetic field on BWI is also studied.

A useful design technique of helix pitch profile for high efficiency TWTs

A useful design technique of helix pitch profile for high-efficiency Traveling-Wave tubes (TWTs) is put forward. The purpose of the design technique is to increase the normalized axial growth rate of ac electric field amplitude by selecting an appropriate helix pitch profile and so that the power and efficiency are maximized.

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.

Magnetic Focusing Simulator: A 3-D Finite-Element Permanent-Magnet Focusing System Design Tool

This paper reports the development of a 3-D finite-element design tool for the design of permanent-magnet focusing system called the magnetic focusing simulator (MFS). It is a new module of microwave-tube simulator suite developed by the University of Electronic Science and Technology of China. MFS specifically targets problem classes including periodic permanent magnet, wiggler, permanent-magnet quadrupoles, periodic cusped magnet, and so on. MFS is a finite-element code of magnetic scalar potential and is a solver of magnetostatic field. It can be used for designing, optimizing, testing, and validating the permanent-magnetic focusing systems. The theory of MFS is discussed in detail in this paper. Besides, the accuracy is compared with the commercial software ANSYS Maxwell, and the performance of MFS is also shown.