Alexander V. Mitrofanov

Spectral filtration of XUV radiation with the help of thin film filters in the TEREK-C solar telescope and RES-C spectroheliograph

The characteristics of different types of thin film XUV filters for the TEREK-C solar telescope and the REC-C spectroheliograph developed in the framework of the CORONAS-I program are presented. We describe the design and properties of Al-Formvar composite filters on rigid mesh supports with a spacing of 0.7 mm and 2 mm, which have been mounted in front of the XUV spectral channels of both instruments. It was proposed to use thin films of SiC as bandpass filters with high transparency in the 13 - 30 nm spectral region and effective cutoff blocking of strong solar Lα (121.7 nm) line radiation. The Al and SiC thin films on fine porous polymer membranes with through pores were placed in close proximity of the entrance plane of the image detectors, designed as a combination of open type microchannel plate and CCD-matrix. The problem of elimination of the influence of diffraction effects on X-ray images in the telescope focal plane is considered. All filters have sustained without damage the launching overloads (the launch took place on March 12, 1994) and successfully worked in the TEREK-C and the RES-C instruments.

Issues of laser plasma sources for soft x-ray projection lithography

Abstract Results of optimization of an excimer laser-induced plasma x-ray source for projection lithography in the range λ = 13–15 nm are reported. A conversion efficiency of >0.7% in 2% BW has been achieved with high-Z target materials. Two methods of reducing contamination of optical elements by target debris have been tested: usage of a thin target layer (for Ta 1 μm was found to be optimal) and of a heavy buffer gas. The effect of the use of Ta-tape target and Kr buffer gas has been measured by determining the reflectivity of a Mo-Si multilayer sample after 10 5 shots.

SiC: filter for extreme ultraviolet

It is proposed to use thin films of silicon carbide as Extreme Ultraviolet bandpass filters transparent within 135-304 A band and with excellent cutoff blocking of the strong L(alpha ) 1216 A line radiation. Mesh or particle track porous membrane supporting 200-800 A thickness SiC filters have been made by RF sputtering techniques. We describe the design and performance of these filters. Such type SiC filter was used in front of the microchannel plate detector of the TEREK X-Ray Telescope mounted on the Solar Observatory CORONAS-I which was successfully launched on March 2, 1994.

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.

Optimization of excimer laser-induced x-ray sources for soft x-ray projection lithography

We report results on high power excimer lasers and their application to generating laser plasma soft x-ray sources. A conversion efficiency of laser light to monochromatized soft x- ray radiation of 0.7% has been achieved at 13.5 nm (2% BW). Two methods to mitigate the production of plasma debris have been analyzed: tape targets and the use of Kr as a buffer gas. The optimal coating thickness of tape targets coated with Ta has been determined as 1 micrometers . Ta tape targets and the Kr buffer were used in a debris contamination test of 105 pulses and evaluated by the loss in reflectivity of a normal incidence Mo-Si multilayer mirror.