We present an analysis of electromagnetic oscillations in a spherical conducting cavity filled concentrically with either dielectric or vacuum layers. The fields are given analytically, and the resonant frequency is d...We present an analysis of electromagnetic oscillations in a spherical conducting cavity filled concentrically with either dielectric or vacuum layers. The fields are given analytically, and the resonant frequency is determined numerically. An important special case of a spherical conducting cavity with a smaller dielectric sphere at its center is treated in more detail. By numerically integrating the equations of motion we demonstrate that the transverse electric oscillations in such cavity can be used to accelerate strongly relativistic electrons. The electron’s trajectory is assumed to be nearly tangential to the dielectric sphere. We demonstrate that the interaction of such electrons with the oscillating magnetic field deflects their trajectory from a straight line only slightly. The Q factor of such a resonator only depends on losses in the dielectric. For existing ultra low loss dielectrics, Q can be three orders of magnitude better than obtained in existing cylindrical cavities.展开更多
为了解决永磁直线同步电机(permanent magnet linear synchronous motor,PMLSM)运行过程中对系统参数扰动及端部效应等不确定因素敏感的问题,提出了一种PMLSM的非线性鲁棒控制方法。利用反馈线性化的思想,对PMLSM数学模型进行变换得到...为了解决永磁直线同步电机(permanent magnet linear synchronous motor,PMLSM)运行过程中对系统参数扰动及端部效应等不确定因素敏感的问题,提出了一种PMLSM的非线性鲁棒控制方法。利用反馈线性化的思想,对PMLSM数学模型进行变换得到包含不确定因素的准线性化且解耦的模型。采用msat函数的思想方法,设计了固定边界层滑模控制器,确保系统鲁棒性。同时给出了力观测器的设计方法估计新模型中未知的负载力。不需要知道系统参数的精确数值,通过确定其范围就可以使控制器得到良好的鲁棒性。仿真与实验结果均验证了文中所提出方法的正确性和控制策略的有效性。展开更多
文摘We present an analysis of electromagnetic oscillations in a spherical conducting cavity filled concentrically with either dielectric or vacuum layers. The fields are given analytically, and the resonant frequency is determined numerically. An important special case of a spherical conducting cavity with a smaller dielectric sphere at its center is treated in more detail. By numerically integrating the equations of motion we demonstrate that the transverse electric oscillations in such cavity can be used to accelerate strongly relativistic electrons. The electron’s trajectory is assumed to be nearly tangential to the dielectric sphere. We demonstrate that the interaction of such electrons with the oscillating magnetic field deflects their trajectory from a straight line only slightly. The Q factor of such a resonator only depends on losses in the dielectric. For existing ultra low loss dielectrics, Q can be three orders of magnitude better than obtained in existing cylindrical cavities.
文摘为了解决永磁直线同步电机(permanent magnet linear synchronous motor,PMLSM)运行过程中对系统参数扰动及端部效应等不确定因素敏感的问题,提出了一种PMLSM的非线性鲁棒控制方法。利用反馈线性化的思想,对PMLSM数学模型进行变换得到包含不确定因素的准线性化且解耦的模型。采用msat函数的思想方法,设计了固定边界层滑模控制器,确保系统鲁棒性。同时给出了力观测器的设计方法估计新模型中未知的负载力。不需要知道系统参数的精确数值,通过确定其范围就可以使控制器得到良好的鲁棒性。仿真与实验结果均验证了文中所提出方法的正确性和控制策略的有效性。
