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Ishikawa, T.

Paper Title Page
MOPC018 Seeding the FEL of the SCSS Test Accelerator with the 5th Harmonic of a Ti: Sa Laser Produced in Gases 109
 
  • G. Lambert, O. V. Chubar, M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • M. Bougeard, B. Carré, D. Garzella, O. B. Gobert, M. Labat, H. Merdji, P. Salieres
    CEA, Gif-sur-Yvette
  • T. Hara, T. Ishikawa, H. Kitamura, T. Shintake, M. Yabashi
    RIKEN/SPring-8, Hyogo
  • K. Tahara, Y. T. Tanaka, T. Tanikawa
    RIKEN Spring-8 Harima, Hyogo
 
  We present the strong amplification of the 5th harmonic of a Ti: Sa laser (10 Hz, 100 fs) generated in a Xe gas cell, i.e. 160 nm, and the generation of intense and coherent odd and even Non Linear Harmonics (NLH) from 80 nm to 23 nm. The experiment has been carried out on the SCSS (SPring-8 Compact SASE Source, Japan) Test Accelerator FEL. This facility is mainly based on a thermionic cathode electron gun, a C-band LINAC (5712 MHz, 35 MV/m) and an in-vacuum undulator (15 mm of period, 2 sections of 4.5 m length). The external source is properly focused in the first undulator section in order to efficiently interact with the electron beam (150 MeV, 10 Hz, 0.5-3 ps). In case of high peak current mode, the 160 nm seed light is amplified by a factor of 7000 in the first undulator section. Moreover, the amplification can be observed even for very low HHG seed level. This result opens new perspectives for seeding at short wavelengths in the XUV to soft X-Ray region. Association with NLH, HGHG (High Gain Harmonic Generation) and/or cascade schemes would allow the generation of fully coherent X-ray radiations from the “water window” spectral range to the Angstrom region.  
WEOAM01 Operation Status of the SCSS Test Accelerator: Continuous Saturation of SASE FEL at the Wavelength Range from ~50 to 60 nanometers 1944
 
  • H. Tanaka, T. Fukui, T. Hara, A. Higashiya, N. Hosoda, T. Inagaki, S. I. Inoue, T. Ishikawa, H. Kitamura, M. K. Kitamura, H. Maesaka, M. Nagasono, T. Ohshima, Y. Otake, T. Sakurai, T. Shintake, K. Shirasawa, T. Tanaka, K. Togawa, M. Yabashi
    RIKEN/SPring-8, Hyogo
  • T. Asaka, T. Hasegawa, H. Ohashi, S. Takahashi, S. Tanaka
    JASRI/SPring-8, Hyogo-ken
  • T. Tanikawa
    RIKEN Spring-8 Harima, Hyogo
 
  The SPring-8 compact SASE source (SCSS) test accelerator for XFEL/SPring-8 was constructed in 2005. The first lasing at 49 nm, though not reached saturation, was observed with the 250-MeV electron beam in June 2006. Towards the saturation, we started stabilizing the RF system in the injector section, which dramatically stabilized the lasing condition. The stable operation enables us to tune each of the machine parameter precisely by using the lasing response. The second undulator, which did not sufficiently contribute to the first lasing because of large multipole field errors, was replaced by new one. These improvements led us to the successful observation of SASE saturation at the wavelength ranging from ~50 to 60 nm in September 2007. A pulse-energy of 30 uJ is routinely obtained at 60 nm. Analysis of the obtained SASE saturation data with a 3D-FEL simulation code, SIMPLEX, suggests that the electron beam emittance is almost unchanged through the bunch compression process. The stable and intense EUV SASE FEL has been offered for user experiments since October 2007. The achieved electron beam performance, lasing property as well as the latest analysis result will be presented.  
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THPP050 Recent Status of Laser Cooling for Mg Realized at S-LSR 3476
 
  • A. Noda, M. Ikegami, T. Ishikawa, M. Nakao, T. Shirai, H. Souda, M. Tanabe, H. Tongu, A. Wakita
    Kyoto ICR, Uji, Kyoto
  • M. Grieser
    MPI-K, Heidelberg
  • I. N. Meshkov, A. V. Smirnov
    JINR, Dubna, Moscow Region
  • K. Noda
    NIRS, Chiba-shi
 
  At an ion storage and cooler ring, S-LSR, a laser cooling has been applied to the 40 keV 24Mg+ ion beam guiding a laser with the wave length of 280nm parallel to the ion beam together with the deceleration by an induction voltage. Up to now, the longitudinal temperature has been cooled down to 3.6 Kelvin for the ion number of 3x104 although the transverse one still remains around 500 Kelvin. The longitudinal temperature is limited by the heat transfer from the transverse degree of freedom through intra-beam scattering, which becomes stronger according to increase of ion number. It is found that the equilibrium longitudinal temperature is linearly coupled with the transverse one* for our experimental condition up to now. In the present paper, recent experimental data will be presented together with the procedure of beam diagnosis with the use of optical methods using a spontaneous emission of the Mg ions. Possible approach to realize the resonant coupling through synchro-betatron coupling** is also to be presented.

* M. Tanabe et al., To be published in Applied Physics Express (APEX).
** Okamoto, A. M. Sessler, D Möhl, Phys. Rev. Lett. 72 (1994)3977.

 
THPP054 Laser Cooling of Bunched Ion Beam at S-LSR 3488
 
  • H. Souda, M. Ikegami, T. Ishikawa, M. Nakao, A. Noda, T. Shirai, M. Tanabe, H. Tongu, A. Wakita, M. Yamada
    Kyoto ICR, Uji, Kyoto
 
  S-LSR is an ion storage ring equipped with an electron cooler and a laser cooling system. The laser cooling experiments of coasting beams were carried out during last year*. Now we started bunched beam laser cooling. 40keV Mg+ beams are bunched by an untuned RF cavity for harmonic number 5-50, and is cooled by a single 280nm laser. Bunch length are measured by electrostatic pickups. When RF harmonic number is five, bunch lengths is shorten from 1m to under 0.14m by laser cooling. Since the bunch length after cooling is shorter than present monitor resolution, fluorescence measurement is in preparation. We have installed another small RF cavity for harmonic number 100. Synchrotron-betatron coupling will be induced by dispersion at the place of this cavity**. This effect is expected to realize three dimensional laser cooling. In this paper we present the result of bunched beam cooling and the trial to three dimensional laser cooling.

*M. Tanabe et al. Appl. Phys. Express, in press.
**H. Okamoto. Phys. Rev. E 50, 4982 (1994).