ZhongHai Yang

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.

Thermal Analysis of Novel Helix TWTs

Consider the thermal contact resistance and the thermal conductivity as the function of temperature, the power dissipation of BeO and diamond-supported, the diamond-studded and the full-diamond helical slow-wave structures (HSWS) are computed using ANSYS. Results indicated the studded-diamond circuit is better than the diamond-support circuit. Especially, the full diamond circuit demonstrated advantage of excellent heat removing

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.

Analysis of a U-shaped vane-loaded helical slow-wave structure for wideband travelling-wave tubes

The dispersion equation and interaction impedance of a U-shaped vane-loaded helical slow-wave structure (SWS) is obtained by considering the azimuthal space harmonic in the non-vane region and the helical tape thickness, using the field theory matching method in the azimuthal field discontinuity. The theoretical calculation by electromagnetic analysis is consistent with the simulation result by MAFIA, which can explain some physical essence of the SWS. In the helical SWS, negative dispersion is reported to reduce the second harmonic content of a wideband travelling-wave tube at the low-frequency end of the band. When the SWS is assembled, the support rods are easily located in the groove of the vane. The solution provides a new instruction method for other types of vane-loaded helical SWS.

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.

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).

A 3-D Finite-Element Eigenvalue Analysis of Slow-Wave Structures of Traveling-Wave Tubes Without Matching Meshes

A novel 3-D finite-element modeling technique without matching meshes for the eigenvalue analysis of arbitrary lossy slow-wave structures (SWSs) of traveling-wave tubes is presented. By simulating two examples, it is shown that the cold parameters of SWSs can be accurately and quickly obtained without matching meshes when using this technique. Moreover, a new second-order transverse electric periodic boundary condition (PBC) is proposed to improve the modeling efficiency of lossy SWSs in the nonmatching meshes case, and this technique is very suitable for application of the rotated PBC. This technique would make the modeling of SWSs more flexible, cheaper, and more efficient.

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).