IPAC'10 - List of Authors (Higashimura, K.)

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Higashimura, K.

Paper	Title	Page
TUPEC008	Cavity Detuning Method to Compensate Beam Energy Decrement in Thermionic RF Gun due to Back-bombardment Effect	1725
	H. Zen UVSOR, Okazaki M. A. Bakr, K. Higashimura, T. Kii, R. Kinjo, K. Masuda, K. Nagasaki, H. Ohgaki Kyoto IAE, Kyoto H. Zen Sokendai - Okazaki, Okazaki, Aichi
	Thermionic RF guns are compact, economical and high brightness electron sources. However, when the guns are used for a driver linac of oscillator-type Free Electron Lasers (FELs), which requires moderate bunch charge (several tens pico-coulomb) and long macro-pulse duration (several micro-seconds), the guns have been suffered from the back-bombardment effect. The effect induces beam current increment in a macro-pulse. And consequently the current increment leads to decrement of beam energy during a macro-pulse and significantly limits the beam macro-pulse duration after some bending magnets. Our group found a new energy compensation scheme called as cavity detuning* and the method was introduced to compensate the beam energy decrement in the thermionic RF gun used for KU-FEL**. In this presentation, we will introduce the principle of the method and experimental results. Detailed analysis of the method will be also presented. C.B. McKee et al., NIM, A296, pp. 716-719, 1990. H. Zen et al., IEEE Trans. of Nucl. Sci., vol. 56, No. 3, pp. 1487-1491 * T. Yamazaki et al., Proc. of 23rd FEL Conf., pp. II-13-14, 2002.

Paper

Title

Page

TUPEC008

Cavity Detuning Method to Compensate Beam Energy Decrement in Thermionic RF Gun due to Back-bombardment Effect

1725

H. Zen
UVSOR, Okazaki
M. A. Bakr, K. Higashimura, T. Kii, R. Kinjo, K. Masuda, K. Nagasaki, H. Ohgaki
Kyoto IAE, Kyoto
H. Zen
Sokendai - Okazaki, Okazaki, Aichi

Thermionic RF guns are compact, economical and high brightness electron sources. However, when the guns are used for a driver linac of oscillator-type Free Electron Lasers (FELs), which requires moderate bunch charge (several tens pico-coulomb) and long macro-pulse duration (several micro-seconds), the guns have been suffered from the back-bombardment effect*. The effect induces beam current increment in a macro-pulse. And consequently the current increment leads to decrement of beam energy during a macro-pulse and significantly limits the beam macro-pulse duration after some bending magnets. Our group found a new energy compensation scheme called as cavity detuning** and the method was introduced to compensate the beam energy decrement in the thermionic RF gun used for KU-FEL***. In this presentation, we will introduce the principle of the method and experimental results. Detailed analysis of the method will be also presented.

* C.B. McKee et al., NIM, A296, pp. 716-719, 1990.
** H. Zen et al., IEEE Trans. of Nucl. Sci., vol. 56, No. 3, pp. 1487-1491
*** T. Yamazaki et al., Proc. of 23rd FEL Conf., pp. II-13-14, 2002.