Coherent enhancement of Smith-Purcell radiation has attracted people's attention not only in adopting a better source but also in beam diagnostics aspect.In this paper,we study the intrinsic mechanism of coherent ...Coherent enhancement of Smith-Purcell radiation has attracted people's attention not only in adopting a better source but also in beam diagnostics aspect.In this paper,we study the intrinsic mechanism of coherent Smith-Purcell radiation on the basis of the van den Berg model.The emitted power of Smith-Purcell radiation is determined by the bunch profile in transverse and longitudinal directions.For short bunch whose longitudinal pulse length is comparable with the radiation wavelength,it can be concluded approximately that the power is proportional to the square number of electrons per bunch.展开更多
We adopt the groove guide as the cavity of the undulator to reduce the diffraction effect. The groove guide has the advantages of lower surface energy loss, larger power capacity, less modes, and larger structure dime...We adopt the groove guide as the cavity of the undulator to reduce the diffraction effect. The groove guide has the advantages of lower surface energy loss, larger power capacity, less modes, and larger structure dimension over the traditional method waveguide. The attenuation calculation is given in this paper including the cavity optimization. And the dispersive character indicates that the oscillator can work in different modes with the change of the electron beam energy.展开更多
Based on the femtosecond accelerator device, we are planning to build a broad band and tunable THz source using the Smith-Purcell radiation mechanism. Coherent Smith-Purcell radiation could be achieved owing to the su...Based on the femtosecond accelerator device, we are planning to build a broad band and tunable THz source using the Smith-Purcell radiation mechanism. Coherent Smith-Purcell radiation could be achieved owing to the super-short bunch produced in the device. To shorten the distance between the beam and grating, we use Transport to match the beta function producing a sheet beam on the grating surface. The optimization of grating length, groove depth and groove width are given in the paper. Then the radiation power for the shallow and deep grating using these parameters are presented. The detection devices and methods are also briefly discussed.展开更多
We present a design study of a free electron laser(FEL) oscillator for high power THz source experiments on the basis of the Shanghai femtosecond accelerator device.A circular groove guide is used as a new interaction...We present a design study of a free electron laser(FEL) oscillator for high power THz source experiments on the basis of the Shanghai femtosecond accelerator device.A circular groove guide is used as a new interaction structure.Plane metal meshes are used as upstream and downstream mirrors of the resonator.The general design parameters are presented.We analyzed the spontaneous emission and stimulated emission in the oscillator using these parameters.展开更多
With the right choice of parameters in the free electron laser (FEL) scheme, the undulator can be primarily operated at high order harmonic modes and the harmonic radiation is expected to be significantly enhanced. Re...With the right choice of parameters in the free electron laser (FEL) scheme, the undulator can be primarily operated at high order harmonic modes and the harmonic radiation is expected to be significantly enhanced. Recently, the possibility of proof-of-principle harmonic operation experiments on the basis of the Shanghai deep ultraviolet (SDUV) FEL test facility has been studied. In this paper, the principle of harmonic operation, three dimensional numerical approaches, and detailed performances of proposed harmonic operation at SDUV FEL are presented.展开更多
Based on the femtosecond accelerator device which was built at the Shanghai Institute of Applied Physics (SINAP), recently a modified far infrared Michelson interferometer has been developed to measure the length of e...Based on the femtosecond accelerator device which was built at the Shanghai Institute of Applied Physics (SINAP), recently a modified far infrared Michelson interferometer has been developed to measure the length of electron bunches via the optical autocorrelation method. Compared with our former normal Michelson interferometer, we use a hollow retroreflector instead of aflat mirror as the reflective mirror. The experimental setup and results of the bunch length measurement will be described in this paper.展开更多
In recent years, people are dedicated to the research work of finding compact THz sources with high emission power. Smith-Purcell radiation is qualified for the possibility of coherent enhancement due to the effect of...In recent years, people are dedicated to the research work of finding compact THz sources with high emission power. Smith-Purcell radiation is qualified for the possibility of coherent enhancement due to the effect of FEL mechanism. The compact experiment device is expected to produce hundreds mW level THz ray. The electron beam with good quality is provided under the optimized design of the electron gun. Besides, the grating is designed as an oscillator without any external feedbacks. While the beam passes through the grating surface, the beam bunching will be strong and the second harmonics enhancement will be evident, as is seen from the simulation results.展开更多
基金Supported by Major State Basic Research Development Program of China (2002CB713600)
文摘Coherent enhancement of Smith-Purcell radiation has attracted people's attention not only in adopting a better source but also in beam diagnostics aspect.In this paper,we study the intrinsic mechanism of coherent Smith-Purcell radiation on the basis of the van den Berg model.The emitted power of Smith-Purcell radiation is determined by the bunch profile in transverse and longitudinal directions.For short bunch whose longitudinal pulse length is comparable with the radiation wavelength,it can be concluded approximately that the power is proportional to the square number of electrons per bunch.
基金Supported by Major State Basic Research Development Program of China (2002CB713600)
文摘We adopt the groove guide as the cavity of the undulator to reduce the diffraction effect. The groove guide has the advantages of lower surface energy loss, larger power capacity, less modes, and larger structure dimension over the traditional method waveguide. The attenuation calculation is given in this paper including the cavity optimization. And the dispersive character indicates that the oscillator can work in different modes with the change of the electron beam energy.
基金Supported by Major State Basic Research Development Program of China (2002CB713600)
文摘Based on the femtosecond accelerator device, we are planning to build a broad band and tunable THz source using the Smith-Purcell radiation mechanism. Coherent Smith-Purcell radiation could be achieved owing to the super-short bunch produced in the device. To shorten the distance between the beam and grating, we use Transport to match the beta function producing a sheet beam on the grating surface. The optimization of grating length, groove depth and groove width are given in the paper. Then the radiation power for the shallow and deep grating using these parameters are presented. The detection devices and methods are also briefly discussed.
基金Supported by Major State Basic Research Development Program of China (2002CB713600)
文摘We present a design study of a free electron laser(FEL) oscillator for high power THz source experiments on the basis of the Shanghai femtosecond accelerator device.A circular groove guide is used as a new interaction structure.Plane metal meshes are used as upstream and downstream mirrors of the resonator.The general design parameters are presented.We analyzed the spontaneous emission and stimulated emission in the oscillator using these parameters.
基金Supported by Shanghai Natural Science Foundation (09JC1416900)
文摘With the right choice of parameters in the free electron laser (FEL) scheme, the undulator can be primarily operated at high order harmonic modes and the harmonic radiation is expected to be significantly enhanced. Recently, the possibility of proof-of-principle harmonic operation experiments on the basis of the Shanghai deep ultraviolet (SDUV) FEL test facility has been studied. In this paper, the principle of harmonic operation, three dimensional numerical approaches, and detailed performances of proposed harmonic operation at SDUV FEL are presented.
基金Supported by Major State Basic Research Development Program of China (2002CB713600)
文摘Based on the femtosecond accelerator device which was built at the Shanghai Institute of Applied Physics (SINAP), recently a modified far infrared Michelson interferometer has been developed to measure the length of electron bunches via the optical autocorrelation method. Compared with our former normal Michelson interferometer, we use a hollow retroreflector instead of aflat mirror as the reflective mirror. The experimental setup and results of the bunch length measurement will be described in this paper.
文摘In recent years, people are dedicated to the research work of finding compact THz sources with high emission power. Smith-Purcell radiation is qualified for the possibility of coherent enhancement due to the effect of FEL mechanism. The compact experiment device is expected to produce hundreds mW level THz ray. The electron beam with good quality is provided under the optimized design of the electron gun. Besides, the grating is designed as an oscillator without any external feedbacks. While the beam passes through the grating surface, the beam bunching will be strong and the second harmonics enhancement will be evident, as is seen from the simulation results.
