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R. G. Cruddace (Naval Research Laboratory)
We describe a new and mature technology, with which it is possible to build astrophysical EUV spectrometers of high resolving power. Solar research has shown that high resolving power is important in applying a wide range of plasma diagnostics unambiguously, and in studying plasma dynamics through measurements of line profiles and Doppler shifts. The regime 100-300 Å is of special importance, as it contains many strong emission and absorption lines from plasmas at 5 104 to 2 107 K, and because in this band the interstellar medium opacity is low enough to permit not only extensive studies of the local galactic disk, but in some directions galactic halo and extragalactic observations.
The instrument concept comprises a multilayer-coated diffraction grating of high ruling density, working at near normal incidence in a Wadsworth mount, which focusses a spectrum onto a microchannelplate focal-plane detector. We summarise the developments over the last decade which have made possible an efficient spectrometer of high resolving power, in particular EUV multilayers and diffraction gratings produced by ion-etching. This included extensive experimental studies of multilayer gratings at the National Synchrotron Light Source at Brookhaven, and culminated in February 2001 in the successfull flight of a prototype spectrometer on a sounding rocket, which obtained a high-resolution spectrum of the white dwarf G191-B2B in the 225-245 Å band. Finally, to further an assessment of the impact of high-resolution spectroscopy on EUV astronomy, we present a strawman design for an orbiting instrument, capable of achieving a resolving power of ~10,000 and an effective area of ~20 cm2 over the band 100-300 Å.
The work described has been supported by the Office of Naval Research and NRL, and by NASA Research Opportunities in Space Science (ROSS) grants.
The author(s) of this abstract have provided an email address for comments about the abstract: cruddace@xip.nrl.navy.mil
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.