Viktor V. Krutov

XUV observations of solar corona in the spirit experiment on board the coronas-F satellite

The images of the solar corona from the limb out to the distance of about 5 solar radii have been obtained for the firs time in the XUV narrow spectral bands and monochromatic lines in the current experiment SPIRIT (SPectroheliographIc soft X-Ray Imaging Telescope). This paper presents the examples of images for the Suns “quiet” atmosphere as well as for some transient and eruptive events in the corona to illustrate the performance of the instrumentation and to point out the way for future studies. The data obtained will be used for diagnostic purposes and modeling of solar wind acceleration, coronal plasma structures and various active phenomena in the solar corona.

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.

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.

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.