The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB&#...The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB's electron in such magnetic field are analyzed by the use of fluid model and the radial force equation in modified Mathieu function form is drawn then.At last a 2.5-D particle in-cell(PIC)simulation code is used to investigate the physical process of the IREB's propagation.In the PIC simulation,the electron beam current,thickness,magnet field amplitude and the beam's initial incident angle related to the stable propagation are mainly discussed.The conclusion is made that several kilo-amperes intense annular electron beam could propagate stably,meanwhile the focusing form of such magnet geometry provides action mechanism for the interaction between beam electrons and microwave in the ubitron.展开更多
Background In an electron linac,the standard bunching system is generally composed of a standing-wave(SW)pre-buncher(PB),a travelling-wave(TW)buncher and a standard TW accelerating structure.Purpose To keep the beam p...Background In an electron linac,the standard bunching system is generally composed of a standing-wave(SW)pre-buncher(PB),a travelling-wave(TW)buncher and a standard TW accelerating structure.Purpose To keep the beam performance similar to the standard bunching system but reduce the cost as much as possible,the hybrid accelerating structure(HAS)was proposed by integrating the PB,the B and the accelerating structure together.Methods The RF design of the HAS was conducted by 2D code SUPERFISH,which is used to determine the dimensions of the SW and TW cells,and 3D code HFSS,which is used to optimize the input and output RF coupler cells.Results The on-axis electric field distribution simulated by HFSS can fully meet the dynamic requirement.The phase jump in SW section is 180◦while the phase advance in TW section is 120°.Conclusion The RF design of the HAS is completed,and the engineering design of the prototype is being conducted.展开更多
基金Supported by the National Natural Science Foundation of China(11475201)the Youth Innovation Promotion Association of Chinese Academy of Sciences,China
文摘The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB's electron in such magnetic field are analyzed by the use of fluid model and the radial force equation in modified Mathieu function form is drawn then.At last a 2.5-D particle in-cell(PIC)simulation code is used to investigate the physical process of the IREB's propagation.In the PIC simulation,the electron beam current,thickness,magnet field amplitude and the beam's initial incident angle related to the stable propagation are mainly discussed.The conclusion is made that several kilo-amperes intense annular electron beam could propagate stably,meanwhile the focusing form of such magnet geometry provides action mechanism for the interaction between beam electrons and microwave in the ubitron.
基金supported by the National Natural Science Foundation of China(11475201)the Youth Innovation Promotion Association of Chinese Academy of Sciences,China.
文摘Background In an electron linac,the standard bunching system is generally composed of a standing-wave(SW)pre-buncher(PB),a travelling-wave(TW)buncher and a standard TW accelerating structure.Purpose To keep the beam performance similar to the standard bunching system but reduce the cost as much as possible,the hybrid accelerating structure(HAS)was proposed by integrating the PB,the B and the accelerating structure together.Methods The RF design of the HAS was conducted by 2D code SUPERFISH,which is used to determine the dimensions of the SW and TW cells,and 3D code HFSS,which is used to optimize the input and output RF coupler cells.Results The on-axis electric field distribution simulated by HFSS can fully meet the dynamic requirement.The phase jump in SW section is 180◦while the phase advance in TW section is 120°.Conclusion The RF design of the HAS is completed,and the engineering design of the prototype is being conducted.
