FEL2012 - List of Authors (Nagasaki, K.)

Paper	Title	Page
TUPD41	Practical Design of Resonance Frequency Tuning System for Coaxial RF Cavity for Thermionic Triode RF Gun	333
	T. Konstantin, Y.W. Choi, H. Imon, T. Kii, R. Kinjo, K. Masuda, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, M. Takasaki, K. Yoshida, H. Zen Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	The FEL radiation production requires temporal stability of electron beam energy. The latter depends directly on the quality of electron gun. The KUFEL(Kyoto University- FEL) facility uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The main disadvantage of using a thermionic RF gun is the effect of backstreaming electrons, which heats up the cathode material during operation and causes energy drop. An additional cavity, triode cavity, for RF gun was designed and fabricated in order to control the electron injection and to mitigate the amount of backstreaming electrons(). The quality factor and the coupling coefficient of the triode cavity with the RF feed coaxial cable were designed to ensure the induction of the required cavity voltage and a wide frequency acceptance(). The corresponded simulations show the power reduction of back streaming electrons for 80% as well as peak current enhancement without emittance degradation(,*). However the fabricated prototype didn't match the designed parameters as tested at low power(*). In this work we report the strategies for correction of deviation from simulated and tested parameters of triode cavity. K.Masuda et al. Prc. FEL 2009, Liverpool K.Masuda et al. Prc. FEL 2006, Berlin * T. Shiiyama et al. Prc. FEL 2007, Novosibirsk **** M.Takasaki et al. Prc. FEL 2010, Malmö

Paper

Title

Page

Practical Design of Resonance Frequency Tuning System for Coaxial RF Cavity for Thermionic Triode RF Gun

333

T. Konstantin, Y.W. Choi, H. Imon, T. Kii, R. Kinjo, K. Masuda, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, M. Takasaki, K. Yoshida, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

The FEL radiation production requires temporal stability of electron beam energy. The latter depends directly on the quality of electron gun. The KUFEL(Kyoto University- FEL) facility uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The main disadvantage of using a thermionic RF gun is the effect of backstreaming electrons, which heats up the cathode material during operation and causes energy drop. An additional cavity, triode cavity, for RF gun was designed and fabricated in order to control the electron injection and to mitigate the amount of backstreaming electrons(*). The quality factor and the coupling coefficient of the triode cavity with the RF feed coaxial cable were designed to ensure the induction of the required cavity voltage and a wide frequency acceptance(***). The corresponded simulations show the power reduction of back streaming electrons for 80% as well as peak current enhancement without emittance degradation(**,***). However the fabricated prototype didn't match the designed parameters as tested at low power(****). In this work we report the strategies for correction of deviation from simulated and tested parameters of triode cavity.
* K.Masuda et al. Prc. FEL 2009, Liverpool
** K.Masuda et al. Prc. FEL 2006, Berlin
*** T. Shiiyama et al. Prc. FEL 2007, Novosibirsk
**** M.Takasaki et al. Prc. FEL 2010, Malmö