title: Damage threshold of coating materials on x-ray mirror for x-ray free electron laser.
abstract: We evaluated the damage threshold of coating materials such as Mo, Ru, Rh, W, and Pt on Si substrates, and that of uncoated Si substrate, for mirror optics of X-ray free electron lasers (XFELs). Focused 1 μm (full width at half maximum) XFEL pulses with the energies of 5.5 and 10 keV, generated by the SPring-8 angstrom compact free electron laser (SACLA), were irradiated under the grazing incidence condition. The damage thresholds were evaluated by in situ measurements of X-ray reflectivity degradation during irradiation by multiple pulses. The measured damage fluences below the critical angles were sufficiently high compared with the unfocused SACLA beam fluence. Rh coating was adopted for two mirror systems of SACLA. One system was a beamline transport mirror system that was partially coated with Rh for optional utilization of a pink beam in the photon energy range of more than 20 keV. The other was an improved version of the 1 μm focusing mirror system, and no damage was observed after one year of operation.
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Koyama
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Hirokatsu
authors.initials: H
authors.lastname: Yumoto
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Miura
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Tono
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Togashi
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inubushi
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Katayama
authors.affiliation: Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Jangwoo
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Matsuyama
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Makina
authors.initials: M
authors.lastname: Yabashi
authors.affiliation: Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Yamauchi
authors.affiliation: Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-Cho, Sayo-Gun, Hyogo 679-5198, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Ohashi