RF deflectors can be used for bunch length measurement with high resolution. This paper describes a completed S-band traveling wave RF deflector and the bunch length measurement of the electron beam produced by the ph...RF deflectors can be used for bunch length measurement with high resolution. This paper describes a completed S-band traveling wave RF deflector and the bunch length measurement of the electron beam produced by the photocathode RF gun of the Shanghai DUV-FEL facility. This is the first time that such a transverse RF deflector has been developed and used to measure the bunch length of picosecond order in China. The deflector＇s VSWR is 1.06, the whole attenuation 0.5 dB, and the bandwidth 4.77 MHz for VSWR less than 1.1. With a laser pulse width of 8.5 ps, beam energy of 4.2 MeV, and bunch charge of 0.64 nC, the bunch lengths for different RF input power into the deflector were measured, and an averaged rms bunch length of 5.25 ps was obtained. A YAG crystal is used as a screen downstream of the deflector, with the calibrated value of 1 pix = 136 μm.展开更多
With the development of free electron laser （FEL） and the international linear collider （ILC）, the electron bunch length is getting smaller and smaller, The traveling-wave transverse RF deflecting structure is an ...With the development of free electron laser （FEL） and the international linear collider （ILC）, the electron bunch length is getting smaller and smaller, The traveling-wave transverse RF deflecting structure is an important part of the RF deflecting method for bunch length measurement and phase space diagnostics. The operation mode in RF deflector is the ＂TM11-like＂ mode. Since the TM11-like mode in this structure has a pair of degenerate dipole modes, two additional holes are provided on either side of each iris to stabilize the mode. The simulation and optimization have been done. A prototype has been fabricated and tested. The cold test results have been compared with the simulations of the first three modes.展开更多
基金Supported by Major State Research Development Program (2002CB713606)
文摘RF deflectors can be used for bunch length measurement with high resolution. This paper describes a completed S-band traveling wave RF deflector and the bunch length measurement of the electron beam produced by the photocathode RF gun of the Shanghai DUV-FEL facility. This is the first time that such a transverse RF deflector has been developed and used to measure the bunch length of picosecond order in China. The deflector＇s VSWR is 1.06, the whole attenuation 0.5 dB, and the bandwidth 4.77 MHz for VSWR less than 1.1. With a laser pulse width of 8.5 ps, beam energy of 4.2 MeV, and bunch charge of 0.64 nC, the bunch lengths for different RF input power into the deflector were measured, and an averaged rms bunch length of 5.25 ps was obtained. A YAG crystal is used as a screen downstream of the deflector, with the calibrated value of 1 pix = 136 μm.
基金Supported by Major State Research Development Program(2002CB713606)
文摘With the development of free electron laser （FEL） and the international linear collider （ILC）, the electron bunch length is getting smaller and smaller, The traveling-wave transverse RF deflecting structure is an important part of the RF deflecting method for bunch length measurement and phase space diagnostics. The operation mode in RF deflector is the ＂TM11-like＂ mode. Since the TM11-like mode in this structure has a pair of degenerate dipole modes, two additional holes are provided on either side of each iris to stabilize the mode. The simulation and optimization have been done. A prototype has been fabricated and tested. The cold test results have been compared with the simulations of the first three modes.
