This paper will describe a new Extreme Ultraviolet (EUV) test facility that is being developed at the Marshall Space
Flight Center (MSFC) to test EUV telescopes. Two flight programs, Hi-C, the high resolution coronal imager (a
sounding rocket program), and SUVI, the Solar Ultraviolet Imager (GOES-R), set the requirements for this new facility.
This paper will discuss those requirements, the EUV source characteristics, the wavelength resolution that is expected
and the vacuum chambers (Stray Light Facility, Xray Calibration Facility and the NSSTC EUV test chamber) where this
facility will be used.
The Reflection Grating Spectrometer of the Constellation-X mission has
two strong candidate configurations. The first configuration, the
in-plane grating (IPG), is a set of reflection gratings similar to
those flown on XMM-Newton and has grooves perpendicular to the
direction of incident light. In the second configuration, the
off-plane grating (OPG), the grooves are closer to being parallel to
the incident light, and diffract along a cone. It has advantages of
higher packing density, and higher reflectivity. Confinement of these
gratings to sub-apertures of the optic allow high spectral
resolution. We have developed a raytrace model and analysis technique
for the off-plane grating configuration. Initial estimates indicate
that first order resolving powers in excess of 1000 (defined with
half-energy width) are achievable for sufficiently long wavelengths
(λ ≥ 12Å), provided separate accommodation is made
for gratings in the subaperture region farther from the zeroth order
location.
We report on progress in developing low-cost methods for shaping thin-foil glass x-ray optics. Such optics might serve as substrates for reflection gratings or as foil mirrors in high-throughput missions such as Constellation-X. Novel thermal shaping to lithographically defined pin chucks leads to the desired shape with high accuracy, thereby avoiding the need for replication. To demonstrate this method we have produced 200 micron-thick glass sheets with sub-micron flatness and half power diameter below 10 arc seconds. We also present a process for depositing low-stress metallic coatings that provides high x-ray reflectivity without significant foil distortion.
The High Energy Transmission Grating Spectrometer (HETGS) is one of the scientific instruments being developed for NASA's Advanced X-ray Astrophysics Facility (AXAF), scheduled for launch in 1998. The HETGS will be capable of measuring spectra with high resolution and sensitivity from a variety of compact and slightly extended cosmic X-ray sources. In this paper we describe the overall design of the HETGS and its expected scientific performance. The HETGS consists of two arrays of gold grating elements (High-Energy gratings [HEGs] and Medium-Energy Gratings [MEGs] which are optimized for the energy ranges 0.8-10 keV [HEG] and 0.4-5 keV [MEG]). The details of the grating elements and their fabrication methods are described in Schattenburg et al. (this conference). The gratings are mounted on a support plate which can be inserted immediately behind the AXAF telescope assembly. X-rays diffracted by the gratings are dispersed onto the focal plane detector strips which are components of either of the two AXAF imagers (the HRC or ACIS). The two kinds of gratings are oriented at a slight angle with respect to each other so that the dispersed spectra form a shallow 'X' on the readout device. The gratings and detectors are mounted on a Rowland torus to correct for most of the optical aberrations. The grating-detector combination achieves resolving powers (E/(Delta) E) as high as 1000 at some energies, and has significant effective area (10-200 square cm) for all energies 400 eV < E < 10 keV.
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