Table of Contents
X-Ray Optics and Instrumentation
Volume 2010, Article ID 583626, 10 pages
http://dx.doi.org/10.1155/2010/583626
Research Article

Measuring Curved Crystal Performance for a High-Resolution, Imaging X-Ray Spectrometer

1National Security Technologies, LLC (NSTec), 161 S. Vasco Road, Livermore, CA 94550, USA
2Lawrence Livermore National Laboratory (LLNL), 7000 East Avenue, Livermore, CA 94550, USA

Received 16 December 2009; Accepted 7 June 2010

Academic Editor: Gene Ice

Copyright © 2010 Michael J. Haugh and Richard Stewart. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper describes the design, crystal selection, and crystal testing for a vertical Johann spectrometer operating in the 13 keV range to measure ion Doppler broadening in inertial confinement plasmas. The spectrometer is designed to use thin, curved, mica crystals to achieve a resolving power of E/ΔE>2000. A number of natural mica crystals were screened for flatness and X-ray diffraction width to find samples of sufficient perfection for use in the instrument. Procedures to select and mount high quality mica samples are discussed. A diode-type X-ray source coupled to a dual goniometer arrangement was used to measure the crystal reflectivity curve. A procedure was developed for evaluating the goniometer performance using a set of diffraction grade Si crystals. This goniometer system was invaluable for identifying the best original crystals for further use and developing the techniques to select satisfactory curved crystals for the spectrometer.