Design of a two-cell rf-deflector cavity for ultra-short electron bunch measurement

作者：Nishimura Y; Sakaue K^*; Nishiyama M; Takahashi T; Washio M; Takatomi T; Urakawa J

来源：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment , 2014, 764: 291-298.

DOI：10.1016/j.nima.2014.07.035

• rf electron gun
• rf deflector cavity
• Ultra-short electron bunch measurement

For a longitudinal characterization of an ultra-short electron bunch, an rf-deflector cavity is the best resolution technique that can directly convert longitudinal distribution to transverse. This paper describes the principle of longitudinal diagnostics using an rf-deflector cavity, the design details of an rf-deflector cavity and the results of rf-characteristics for a manufactured cavity. The cavity is based on a rectangular two-cell structure operating on standing wave pi-mode, dipole (TM120) mode at 2856 MHz. We have confirmed using HFSS simulation that this cavity can produce a deflecting voltage of 1.63 MV with an input rf-power of 750 kW. The results of low power rf-measurement of the manufactured cavity show an effective deflecting voltage of 1.00 MV which corresponds to a temporal resolution of 58 fs (rms) (250 fs/mm on the profile monitor) with 750 kW input rf-power, drift length L of 1 m and initial size sigma(off) of 230 mu m. These results indicate that we have successfully achieved our target: temporal resolution of less than 100 fs with an electron bunch with energy of 4.5 MeV and charge of 100 pC.

• 出版日期2014-11-11