三维全电磁粒子模拟技术在真空电子器件中的应用研究

Research on Vacuum Electron Devices with 3D Fully Electromagnetic Particle-in-Cell Simulation Technology

全电磁粒子模拟技术用于求解带电粒子与电磁场之间的非线性相互作用,已成功地应用于真空电子器件的设计以及参数优化,随着真空电子器件工作频率达到太赫兹波段,全电磁粒子模拟算法需要采用共形算法提高电磁场的计算精度以及准确描述电子束的运动状态。较高输出功率水平一直是真空电子器件的研究热点,为了避免高功率所带来的脉冲缩短现象,采用过模结构能进一步提高真空电子器件的功率容量,但是也会导致器件内部的模式竞争加剧,另外阴极产生电子的不均匀性会进一步加剧器件内部的模式竞争问题,导致非轴对称模式被激励。因此需要采用三维全电磁粒子模拟软件对器件的实际工作状态进行数值模拟研究,同时平板结构的新型真空电子器件也需要采用三维全电磁粒子模拟软件进行数值模拟研究。本文详细介绍了三维全电磁粒子模拟所使用的共形算法,并采用自行研制的三维全电磁粒子模拟软件对相对论返波管、径向返波管以及平板回旋管开展了数值模拟研究。

The fully electromagnetic simulation technology can solve the nonlinear interaction between charged particle and electromagnetic field,and it has been utilized in the design and parameter optimization of vacuum electron devices(VEDs)successfully.As the operation frequency of the VEDs reaches terahertz band,the conformal algorithm is integrated in fully electromagnetic particle simulation algorithm to improve the computational accuracy of electromagnetic field and describe the motion state of electron beam precisely.Higher output power has always been the hot spot in the study of VEDs.In order to avoid pulse shortening resulted by high power,overmoded structures are usually adopted to improve the power capability of VEDs.However,the overmoded structure can bring about mode competition,and the non-uniform electron emission even deteriorates the mode competition,which can excite non-axisymmetric mode.3D fully electromagnetic particle simulation is required to study the real working condition of VEDs.Meanwhile,it is also required to numerically study the novel VEDs with planar structure.Conformal algorithm used in 3D fully electromagnetic particle-in-cell code is introduced in this paper,and the X-band relativistic backward wave oscillator,the radial backward wave oscillator and the planar gyrotron with transverse energy extraction are simulated with self-developed 3D conformal fully electromagnetic particle-in-cell code.