Viatcheslav V. Korneev

Diagnostics of the inner corona by XUV-imaging of the sun

Results of solar observations in the XUV-region by means of the telescope TEREK aboard the “Phobos-1” spacecraft are presented. Images of the Sun in the HeII 30,4 nm and FeIX-FeXI 17–18 nm lines were obtained with new types of optical elements — multilayer normal incidence XUV-mirrors and CCD-detectors. About 140 images were obtained with an angular resolution up to 15″ and with exposure times 0.1 to 40 s. In the images one sees the structures in the transition layer from corona to chromosphere which has temperatures in the range 5×104 – 1×106 K as well as in the polar and equatorial coronal holes. Besides, a unique phenomenon — a “blob” in outer corona at a distance about 2 solar radii has been observed. Processing of the data revealed a complex correlation between the XUV-images and the magnetic field structure in the photosphere.

Analysis of the high resolution Mg xi X-ray spectra: II. Physical parameters of the plasma in active region Mcmath 14352

In this paper, the second in a series dealing with high-resolution spectra (9.14–9.33 Å) measured on board the INTERCOSMOS-16 satellite, the analysis of the physical conditions in the coronal part of the McMath 14352 active region is performed. The temperature structure of the emitting plasma is investigated on the basis of the photon fluxes measured in six selected wavelength bands involving the resonance, intercombination, and forbidden lines of the Mg xi ion and a number of satellite lines. Relative line intensities are discussed in terms of the active region plasma density.

Manufacture and testing of x-ray optical elements for the TEREK-C and RES-C instruments on the CORONAS-I mission

The paper describes the main characteristics of the X-ray optical elements (multilayer spherical and aspherical mirrors and diffraction gratings for the 13-30 nm XUV spectral region, Bragg crystal spherical mirrors for the 0.18 and 0.84 m soft X-ray spectral regions) manufactured for the TEREK-C solar XUV telescope array and the RES-C solar spectroheliograph. The TEREK-C and RES-C instruments were placed aboard the CORONAS-I satellite which was launched on March 2, 1994. The testing procedures and results of laboratory tests in X-ray spectral range are also presented.

Analysis of the high-resolution Mg XI X-ray spectra

In part III of the paper containing the analysis of the INTERCOSMOS 16 ADP spectra, it is shown that by assuming the existence of a small admixture (1%) of non-thermal electrons in the active-region plasma it is possible to improve the agreement between measured and calculated fluxes for some spectra. The analysis follows the suggestion contained in the paper by Karev et al. (1980).

On soft electron beams in solar active and flare region

Abstract On the basis of the experimental data obtained from the high resolution X-ray spectra for solar flares and active regions the Suprathermal electron model (SEM) was proposed. This model suggests the existance of the multitemperature structure of the solar plasma emitting Fe and Ca X-rays and the presence of additional electrons with low energies E ⩽ 10 keV and small densities ∼ 1–5% relative to the thermal component.

High-resolution neutron tomography

A neutron tomography technique with a coordinate resolution of several tens of micrometers has been developed. Our results indicate that the technique resolves details with dimensions less than 100μm and measures a linear attenuation of less than similar 0.1 cm−1. Tomograms can be reconstructed using incomplete data. Limits on the resolution of the restored pattern are analyzed, and ways to improve the sensitivity of the technique are discussed.

X-ray spectroheliographs with the Bragg focusing optics for the CORONAS project: design, fabrication, and optical testing

Two x-ray spectroheliographs have been designed for obtaining solar images in about 8.42 angstrom and in 1.86 angstrom spectral regions with high spatial and spectral resolution. In both devices unique optical elements-focusing Bragg crystal mirrors are used. Technologies of their production are described here. These mirrors were tested in the x-ray region for their iamging and dispersive properties. These calibration results are presented.

Analysis of the high-resolution x-ray spectra obtained aboard the intercosmos 16 satellite: I: Identification of the lines in the 9.14?9.33 spectral region

The Bragg-type, flat ADP crystal spectrometer, launched on board the INTERCOSMOS 16 satellite has been used for measurements of the X-ray spectra emitted from solar active region plasmas. During the period of the instrument operation (August–September, 1976) only a few active regions were present on the Sun (minimum of the solar activity). About 60 spectra have been registered. In the present paper using a spectrum averaged over 20 scans, we measured the wavelengths corresponding to the statistically significant spectral features seen in this spectrum in the wavelength range 9.14–9.33 Å. By comparison with the calculated line wavelengths and intensities predicted in the framework of the thermal model of the ‘average’ active region, we performed the identification of these features. Besides rather prominent resonance, intercombination, and forbidden lines of the He-like ion Mg xi, it was possible to identify the satellite lines which correspond to 1s2nl - 1s2p nl transitions from the states with n = 2, 3, and 4. The present paper is the first in a series dealing with the INTERCOSMOS 16 Mg xi spectra.

On Doppler shifts of the Fe XXV ion resonance line in solar flare X-ray spectra

Doppler shifts of the Fe xxv line in three solar flares show prevalently downward motions with velocities up to 200 km s−1.