Researches On Multi-Physical Co-Simulation Technology Of Traveling-Wave Tube

Traveling-wave tube(TWT) plays a key role in modern military and certain civil fields.During "design-manufacture-test" procedure of traveling-wave tubes,the validity of the earlier design section determines a lot about the efficiency of the subsequent manufacture-test section,which,furthermore,influences the productivity and cost of the entire tube-developing process.At present,tube-designing techniques through only electromagnetic simulation software packages regardless of the factors which would influence the performance of traveling-wave tube in practice such as ambient temperature and mechanical properties will compromise the authenticity of simulation and design seriously.What multi-physical co-simulation means is as follows: for the target geometrical model,with electromagnetic characteristic being the kernel target and electromagnetic simulations carried out on it,the environment(temperature fluctuation or impact response,etc.) that the actual structures created according to simulation model may face during work also counts for traveling-wave tube's comprehensive performance,so thermal and mechanical simulation are carried out on it,too.In this paper,multi-physical co-simulation technology of traveling-wave tube is studied.The coupling relations among electromagnetic,thermal and mechanical simulations concerning traveling-wave tubes are analyzed,and the corresponding technical flowsheets are designed.Based on those researches above,the interface-based co-simulation methodology is employed in the development of first version of the helix travelling-wave tube multi-physical co-simulation module,which is now integrated in Microwave Tube Simulator Suite(MTSS).The module adopts a bus-type structure,whose compositive project can uniformly dispatch thermal,mechanical and electromagnetic solvers,manage all parameters involved in each sub-project,carry out single-step or scanning calculation on these parameters,and finally calculate them in this compositive project and display corresponding post-processing results.At the end of the paper,the module is presented and introduced detailedly and its practical application is presented,including "electro-thermal simulation of collector",and "simultaneous influence of magnetic changes on electron gun,interaction zone and collector".In addition,early researches on such detailed issues as model iteration,transference of simulation attribute and reconstruction of deformed model are carried out and some achievements are achieved.(1)Multi-physical co-simulation process often requires iteration.Simulation results can guide the adjustment of model dimensions of the next round of simulation,and the sub-models for electromagnetic,thermal and mechanical simulations are somewhat simplified from the actual geometric model.New features such as parametric modeling and parameter constraint are added to the current Fast Modeling Tools(FMTools) in this paper,which can accelerate model iteration of traveling-wave tube.In future researches,the sub-models will be able to be distributed according to its simulation project by the modeling tool.(2)Attribute is the calculation flag added by simulator on the BODY(3D) or FACE(2D) of the calculation model.When a model is created by modeling tools,it usually contains only basic information such as name and material.So direct replace of the new model with the former model for iterative calculation is incorrect.In this paper,attributes of the former model are saved temporarily during simulation,and are restored to the new model after it is created but before distributed to corresponding simulation project.(3)After thermal and mechanical simulation,corresponding deformation(expansion and displacement) data of the calculated model are available.In this paper,these data are studied and employed to guide the reconstruction of the deformed model,which is for verification electromagnetic characteristics in turn.