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Title: Damage thresholds for blaze diffraction gratings and grazing incidence optics at an X-ray free-electron laser

Abstract

The Linac Coherent Light Source is upgrading its machine to high repetition rate and to extended ranges. Novel coatings, with limited surface oxidation, which are able to work at the carbon edge, are required. In addition, high-resolution soft X-ray monochromators become necessary. One of the big challenges is to design the mirror geometry and the grating profile to have high reflectivity (or efficiency) and at the same time survive the high peak energy of the free-electron laser pulses. For these reasons the experimental damage threshold, at 900 eV, of two platinum-coated gratings with different blazed angles has been investigated. The gratings were tested at 1° grazing incidence. To validate a model for which the damage threshold on the blaze grating can be estimated by calculating the damage threshold of a mirror with an angle of incidence identical to the angle of incidence on the grating plus the blaze angle, tests on Pt-coated substrates have also been performed. The results confirmed the prediction. Uncoated silicon, platinum and SiB 3 (both deposited on a silicon substrate) were also investigated. In general, the measured damage threshold at grazing incidence is higher than that calculated under the assumption that there is no energy transport frommore » the volume where the photons are absorbed. However, it was found that, for the case of the SiB 3 coating, the grazing incidence condition did not increase the damage threshold, indicating that the energy transport away from the extinction volume is negligible.« less

Authors:
 [1];  [2];  [1];  [3];  [3];  [3];  [3]; ORCiD logo [1]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Helmholtz Zentrum Berlin fur Materialen und Energie, Berlin (Germany)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1413825
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of Synchrotron Radiation (Online)
Additional Journal Information:
Journal Name: Journal of Synchrotron Radiation (Online); Journal Volume: 25; Journal Issue: 1; Journal ID: ISSN 1600-5775
Publisher:
International Union of Crystallography
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; free-electron laser; optical damage; diffraction gratings

Citation Formats

Krzywinski, Jacek, Conley, Raymond, Moeller, Stefan, Gwalt, Grzegorz, Siewert, Frank, Waberski, Christoph, Zeschke, Thomas, and Cocco, Daniele. Damage thresholds for blaze diffraction gratings and grazing incidence optics at an X-ray free-electron laser. United States: N. p., 2018. Web. doi:10.1107/S1600577517016083.
Krzywinski, Jacek, Conley, Raymond, Moeller, Stefan, Gwalt, Grzegorz, Siewert, Frank, Waberski, Christoph, Zeschke, Thomas, & Cocco, Daniele. Damage thresholds for blaze diffraction gratings and grazing incidence optics at an X-ray free-electron laser. United States. doi:10.1107/S1600577517016083.
Krzywinski, Jacek, Conley, Raymond, Moeller, Stefan, Gwalt, Grzegorz, Siewert, Frank, Waberski, Christoph, Zeschke, Thomas, and Cocco, Daniele. 2018. "Damage thresholds for blaze diffraction gratings and grazing incidence optics at an X-ray free-electron laser". United States. doi:10.1107/S1600577517016083.
@article{osti_1413825,
title = {Damage thresholds for blaze diffraction gratings and grazing incidence optics at an X-ray free-electron laser},
author = {Krzywinski, Jacek and Conley, Raymond and Moeller, Stefan and Gwalt, Grzegorz and Siewert, Frank and Waberski, Christoph and Zeschke, Thomas and Cocco, Daniele},
abstractNote = {The Linac Coherent Light Source is upgrading its machine to high repetition rate and to extended ranges. Novel coatings, with limited surface oxidation, which are able to work at the carbon edge, are required. In addition, high-resolution soft X-ray monochromators become necessary. One of the big challenges is to design the mirror geometry and the grating profile to have high reflectivity (or efficiency) and at the same time survive the high peak energy of the free-electron laser pulses. For these reasons the experimental damage threshold, at 900 eV, of two platinum-coated gratings with different blazed angles has been investigated. The gratings were tested at 1° grazing incidence. To validate a model for which the damage threshold on the blaze grating can be estimated by calculating the damage threshold of a mirror with an angle of incidence identical to the angle of incidence on the grating plus the blaze angle, tests on Pt-coated substrates have also been performed. The results confirmed the prediction. Uncoated silicon, platinum and SiB 3 (both deposited on a silicon substrate) were also investigated. In general, the measured damage threshold at grazing incidence is higher than that calculated under the assumption that there is no energy transport from the volume where the photons are absorbed. However, it was found that, for the case of the SiB 3 coating, the grazing incidence condition did not increase the damage threshold, indicating that the energy transport away from the extinction volume is negligible.},
doi = {10.1107/S1600577517016083},
journal = {Journal of Synchrotron Radiation (Online)},
number = 1,
volume = 25,
place = {United States},
year = 2018,
month = 1
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1107/S1600577517016083

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  • The Linac Coherent Light Source is upgrading its machine to high repetition rate and to extended ranges. Novel coatings, with limited surface oxidation, which are able to work at the carbon edge, are required. In addition, high-resolution soft X-ray monochromators become necessary. One of the big challenges is to design the mirror geometry and the grating profile to have high reflectivity (or efficiency) and at the same time survive the high peak energy of the free-electron laser pulses. For these reasons the experimental damage threshold, at 900 eV, of two platinum-coated gratings with different blazed angles has been investigated. Themore » gratings were tested at 1° grazing incidence. To validate a model for which the damage threshold on the blaze grating can be estimated by calculating the damage threshold of a mirror with an angle of incidence identical to the angle of incidence on the grating plus the blaze angle, tests on Pt-coated substrates have also been performed. The results confirmed the prediction. Uncoated silicon, platinum and SiB 3 (both deposited on a silicon substrate) were also investigated. In general, the measured damage threshold at grazing incidence is higher than that calculated under the assumption that there is no energy transport from the volume where the photons are absorbed. Furthermore, it was found that, for the case of the SiB 3 coating, the grazing incidence condition did not increase the damage threshold, indicating that the energy transport away from the extinction volume is negligible.« less
  • Optical elements to be used for x-ray free electron lasers (XFELs) must withstand multiple high-fluence pulses. We have used an ultraviolet laser to study the damage of two candidate materials, crystalline Si and B{sub 4}C-coated Si, emulating the temperature profile expected to occur in optics exposed to XFEL pulses. We found that the damage threshold for 10{sup 5} pulses is {approx}20% to 70% lower than the melting threshold.
  • This paper reports on the Boeing free-electron laser (FEL) optical cavity that has been changed from a simple concentric cavity using two spherical mirrors to a larger grazing-incidence ring resonator. The new resonator consists of two mirror telescopes located at each end of the wiggler with a round-trip path length of approximately 133 m. Each telescope is a grazing-incidence hyperboloid followed by a normal-incidence paraboloid. Initial tests showed that poorly positioned ring focus and unreliable pointing alignment resulted in reduced and structured FEL output. (First lasing operation occurred on March 23 and 24, 1990.) Later efforts concentrated on improving themore » resonator alignment techniques and lowering the single-pass losses. FEL performance and reliability have significantly improved due to better ring alignment. The alignment procedure and recent lasing results are described. The effect the electron beam has on lasing is also discussed. Measurements are presented showing how FEL temporal output and wavelength are sensitive to electron beam energy variations.« less
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  • Diffraction gratings are used from micron to nanometer wavelengths as dispersing elements in optical instruments. At shorter wavelengths, crystals can be used as diffracting elements, but due to the 3D nature of the interaction with light are wavelength selective rather than wavelength dispersing. There is an urgent need to extend grating technology into the x-ray domain of wavelengths from 1 to 0.1 nm, but this requires the use of gratings that have a faceted surface in which the facet angles are very small, typically less than 1°. Small facet angles are also required in the extreme ultra-violet and soft x-ray energymore » ranges in free electron laser applications, in order to reduce power density below a critical damage threshold. In this work, we demonstrate a technique based on anisotropic etching of silicon designed to produce very small angle facets with a high degree of perfection.« less