Hanaki, H.

Paper	Title	Page
WEBAU01	Adaptive 3-D UV-laser Pulse Shaping System to Minimize Emittance for Photocathode RF Gun	298
	T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, A. Mizuno, S. Suzuki, T. Taniuchi, K. Yanagida, H. T. Tomizawa JASRI/SPring-8, Hyogo-ken F. Matsui Industrial Technology Center of Fukui, Fukui City
	We developed an adaptive 3-D shaping (both temporal (1D) and spatial (2D)) short pulse (80 fs~40 ps) UV-laser system as an ideal light source for yearlong stable generation of a low emittance electron beam with a high charge (1~2 nC/pulse). In its current form, the laser’s pulse-energy stability has been improved to 0.2~0.3% (rms; 10 pps, 0.4 TW in femtosecond operation) at the fundamental wavelength and 0.7~1.4% at the third-harmonic generation. Such improvement reflects an ability to stabilize the laser system in a humidity-controlled clean room. The pulse-energy stability of a mode-locked femtosecond oscillator has been continuously held to 0.3% (p-p) for 10 months, 24 hours a day. In addition, the ideal spatial and temporal profiles of a shot-by-shot single UV-laser pulse are essential to suppress emittance growth in an RF gun. We apply a deformable mirror that automatically shapes the spatial UV-laser profile with a feedback routine, based on a genetic algorithm, and a pulse stacker for temporal shaping at the same time. The 3D shape of the laser pulse is spatially top-hat (flattop) and temporally a square stacked pulse. Using a 3D-shaped laser pulse with a diameter of 0.8 mm on the cathode and pulse duration of 10 ps (FWHM), we obtain a minimum normalized emittance of 1.4 π mm mrad with beam energy of 26 MeV.
	Slides
WEPPH053	Non-Destructive Single-Shot 3-D Electron Bunch Monitor with Femtosecond-Timing All-Optical System for Pump & Probe Experiments	472
	H. Hanaki, H. T. Tomizawa JASRI/SPring-8, Hyogo-ken T. Ishikawa RIKEN Spring-8 Harima, Hyogo
	We are developing a 3-D electron bunch monitor based on EO sampling, using yearlong stable femtosecond laser source of SPring-8 RF gun. Our developing single-shot bunch monitor can characterize the 3-D (both longitudinal (1D) and transverse (2D)) distribution and position of an electron bunch with femtosecond resolution. This non-destructive monitor can be used as an electron energy chirping monitor in a dispersive region for X-FEL commissioning. The probe laser for spectral decoding EO sampling is prepared as radically polarized and completely linearly chirped broad-bandwidth (~500nm) supercontinuum. EO-probe is made of 8 EO-crystals with assembling each EO-optical axes along radial beam axes. The probe lineally chirped laser is longitudinally sifted in 8 transverse sectors for spectral decoding. We are planning to use organic polymer film as a femtosecond resolution EO-probe instead of crystals. This 3-D bunch monitor with spectrograph detects and analyzes the wake filed of electron bunches as longitudinally spectral decoding and transversely multi-pole expansion. In addition, we are developing all-optical system for femtosecond-timing pump & probe experiments. The EO-sampled probe laser pulse will use as a femtosecond-timing signal pulse. This signal pulse is amplified with a NOPA (noncollinear optical parametric amplifier), using an SHG of Yb fiber laser as a pump laser.