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 (λ/ λ) of ∼1000. The wavelength coverage, 3.3 -6.1Å, includes emission lines of Si, S, Cl, Ar, and K and in the third diffraction order, the wavelength range includes He-like Fe lines (1.85Å) and Ni lines (1.55Å) 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 measurements of relative and absolute element abundances in the emitting plasma and the temperature distribution of plasma (differential emission measure) over the temperature interval 3 and 50 MK. This paper summarizes the scientific objectives of RESIK and describes the design, characteristics, and performance of the instrument.
The relativistic kinetic equations (RKE) for lepton plasma in the presence of
a strong external magnetic field are derived in Vlasov approximation. The new
RKE for the electron spin distribution function includes the weak interaction
with neutrinos originated by the axial vector current ($\sim c_A$) and provided
by the parity nonconservation. In a polarized electron gas Bloch equation
describing the evolution of the magnetization density perturbation is derived
from the electron spin RKE being modified in the presence of neutrino fluxes.
Such modified hydrodynamical equation allows to obtain the new dispersion
equation in a magnetized plasma from which the neutrino driven instability of
spin waves can be found. It is shown that this instability is more efficient
e.g. in a magnetized supernova than the analogous one for Langmuir waves
enhanced in an isotropic plasma.Comment: 20 pages, no figures, added subsection 2.3 about the lepton current
conservation, to be published in Astroparticle Physic
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