Nishimori, N.
(Nobuyuki Nishimori)

MOPOS29 Analytical Solution of Phase Space Evolution of Electrons in a SASE FEL
Nobuyuki Nishimori (JAERI/FEL, Ibaraki-ken)

The phase space evolution of electrons in a self-amplified spontaneous emission (SASE) FEL operating in the linear regime before saturation is solved analytically from the one dimensional (1D) FEL equaiton. The analytical solution agrees well with a time-dependent numerical simulation which solves the 1D FEL equation in an exact manner and includes a shot-noise effect. The radiation field reaches saturation when the optimum bunching of the electrons is formed on the scale of the resonant wavelength. The optimum bunching leads to the well known saturation condition ρ Nw ~ 1.

THPOS21 Recent Results of the JAERI Energy-Recovery Linac FEL
Ryoichi Hajima, Hokuto Iijima, Nobuhiro Kikuzawa, Eisuke John Minehara, Ryoji Nagai, Nobuyuki Nishimori, Tomohiro Nishitani, Masaru Sawamura (JAERI/FEL, Ibaraki-ken)

A research program towards a high-power FEL utilizing an energy-recovery linac is carried forward at Japan Atomic Energy Research Institute (JAERI). In this paper, we summarize recent results of the research activity at the JAERI ERL-FEL, which include the reinforcement of the injector, replacement of the RF control system and so on.

THPOS22 Misalingment Tolerance of a Hole-Coupling Optical Resonator for JAERI ERL-FEL
Ryoji Nagai, Ryoichi Hajima, Nobuhiro Kikuzawa, Eisuke John Minehara, Nobuyuki Nishimori, Masaru Sawamura (JAERI/FEL, Ibaraki-ken)

The misalignment tolerance of a hole-coupling optical resonator for the JAERI ERL-FEL is estimated with a wavelength of 22 μm by a Fox-Li procedure simulation code. The output power stability depends on the misalignment tolerance. It is found that the misalignment tolerance of the hole-coupling mirror is less than the non-coupling mirror and the offset of the non-coupling mirror is compensable tilting the mirror.

THPOS23 JAERI 200 kV Electron Gun with an NEA-GaAs Photocathode
Tomohiro Nishitani, Ryoichi Hajima, Nobuhiro Kikuzawa, Eisuke John Minehara, Ryoji Nagai, Nobuyuki Nishimori, Masaru Sawamura, T. Yamauchi (JAERI/FEL, Ibaraki-ken)

The GaAs photocathode with negative electron affinity surface (NEA-GaAs) has been expected to be low emittance (<0.5 πmm・mrad) electron beam source. In order to generate low emittance electron beam required from ERL-FEL, we have started the developmental program of a 200keV electron gun with the NEA-GaAs photocathode for the first time in JAERI. An NEA surface has the problem that lifetime is limited by gun vacuum condition and by ion back bombardment between anode- and cathode-electrode. In order to long an NEA surface lifetime, the JAERI 200keV electron gun system consists of a 200kV DC-gun chamber on extreme high vacuum condition and an NEA activation chamber with load-lock system.