CERN Accelerating science

Article
Title	Electron Beam Energy Compensation by Controlling RF Pulse Shape
Author(s)	Kii, T ; Fukui, T ; Kusukame, K ; Masuda, K ; Nakai, Y ; Ohgaki, H ; Yamazaki, T ; Yoshikawa, K ; Zen, H
Affiliation	(Kyoto IAE, Kyoto)
Publication	2005
In:	27th International Conference on Free Electron Lasers, Palo Alto, CA, USA, 21 - 26 Aug 2005, pp.584
Subject category	Accelerators and Storage Rings
Abstract	We have studied on improvement of electron beam macropulse properties from a thermionic RF gun. Though a thermionic RF gun has many salient features, there is a serious problem that back-bombardment effect worsens quality of the beam. To reduce beam energy degradation by this effect, we tried to feed non-flat RF power into the gun. As a result, we successfully obtained about 1.5 times longer macropulse and two times larger total charge per macropulse. On the other hand, we calculated transient evolution of RF power considering non-constant beam loading. The beam loading is evaluated from time evolution of cathode temperature, by use of one dimensional heat conduction model and electron trajectories' calculations by a particle simulation code. Then we found good agreement between the experimental and calculation results. Furthermore, with the same way, we studied the electron beam output dependence on the cathode radius.