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Abstract: |
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We describe the RESIK (REntgenovsky Spektrometr s Izognutymi
Kristalami) instrument, consisting of two double-channel X-ray
spectrometers, designed to observe solar active region and flare
plasmas. RESIK is one of the instruments making up the scientific
payload of the Russian CORONAS-F solar mission. The
uncollimated spectrometer uses two silicon and two quartz bent
crystals observing flare, active region and coronal spectra in
four wavelength bands with a resolving power
 of ~ 1000. The wavelength coverage,
3.3 Å - 6.1 Å, includes emission lines of Si, S, Cl, Ar,
and K and in third diffraction orders, the wavelength range
includes He-like Fe lines (1.85 Å) and Ni lines (1.55 Å) with
dielectronic satellites, emitted during intense, hot flares. The
instrument is believed to be the best calibrated space-borne
crystal spectrometer flown to date. The spectrometer dynamically
adjusts the data gathering intervals from 1 s to 5 minutes,
depending on the level of solar X-ray emission at the time of
observation. The principal aims of RESIK are the measurement of
relative and absolute element abundances in the emitting plasma
and the temperature distribution of plasma (differential emission
measure) over the temperature interval 3 MK and 50 MK. This paper
summarizes the scientific objectives of RESIK and describes the
design, characteristics, and performance of the instrument. |
