Engineering topics

Salashchenko, N. N.

Publications and source records attributed to Salashchenko, N. N..

10 records

DOE OSTI2020

Features of multilayer mirror application for focusing and collimating X-rays from inverse Compton scattering sources

We have analysed the use of X-ray interference multilayer mirrors as the elements of a focusing scheme for a compact source based on inverse Compton scattering. An algorithm is proposed for selecting mirror parameters, which takes into account the properties of the radiation source. The dependence of wavelength on the viewing angle and the energy line broadening for a fixed viewing angle are found to be the main limitations in the use of multilayer mirrors. Efficient radiation collection calls for the application of broadband mirrors. It is shown that the efficiency of multilayer mirrors in a Kirkpatrick – Baez X-ray focusing setup exceeds that of total external reflection mirrors by an order of magnitude, and that stack multilayer mirrors offer a small advantage over the periodic ones. The overall efficiency of source radiation collection in the photon energy range ΔE = 10 – 12 keV amounts to 12 % for the two-mirror Kirkpatrick – Baez setup. For a spectral region with a bandwidth ΔE/E = 3 %, the efficiency ranges up to 69 %. (paper)

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2020

Lasing efficiency of krypton ions in the (8 – 14)-nm band upon pulsed laser excitation

The emission spectra of krypton plasma in the range of 8 – 14 nm upon excitation of a pulsed gas jet by 1.06-mm Nd : YAG laser radiation with a pulse energy of 0.85 J, pulse duration of 5.2 ns, and repetition rate of 10 Hz are investigated. The krypton emission spectrum is a wide (8 – 14 nm) band, peaking at 10.3 nm, which is formed by a series of much narrower lines. The observed lines are identified, and the fraction of laser pulse energy converted into the (8 – 14)-nm emission band and emitted into half-space (2π sr) is determined. The maximum conversion efficiency is found to be 21 %. The expected throughputs of lithographic systems with sources based on Sn, Xe, and Kr ions for different wavelengths, corresponding to the emission peaks of ions of these materials, are compared. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2019

Measurement Error of Interferometers with Diffraction Reference Wave

An experimental setup and results on aberration of sources of a reference spherical wave (SRSW) based on a single-mode optical fiber with a subwavelength output aperture obtained with the aid of an optical part of recording system (OPRS) are presented. SRSW and OPRS are developed for referenceless interferometer with diffraction reference wave. Methods for minimization of the measurement error are proposed. The SRSW and OPRS provide subnanometer measurement accuracy for optics. An increase in the measurement accuracy of the interferometer to a picometer level is discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2019

Fabrication and Study of a Concave Crystal Mirror for the KORTES Project

A method for fabrication of a concave spherical mirror made of crystalline quartz is proposed and X-ray optical properties of the mirror are studied. The radius of curvature is 1630 mm. The shape of the mirror surface is studied using an interferometer with a diffraction reference wave. In the entire processing region, the maximum deviation from the nearest sphere is about 0.2 μm and the rms is 34 nm, so that high quality of imaging is provided with an angular error of about 2″ (angular seconds). Reflection coefficient (about 7%) and lower bound limit of spectral selectivity (λ/δλ ≈ 1775) are determined in the vicinity of a wavelength of λ = 0.834 nm, which is close to the working wavelengths of the MgXII doublet (λ = 0.8418 and 0.8423 nm). Position of the Bragg peak and spectral selectivity remain unchanged upon bending of the crystal mirror within measurement accuracy.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2019

Beryllium as a Material for Thermally Stable X-Ray Mirrors

Thermophysical and mechanical characteristics of beryllium are compared with the corresponding characteristics of promising materials that are used for fabrication of precision mirrors working under high-intensity electromagnetic irradiation. Advantages and prospects for application of beryllium in the third- and fourth-generation synchrotrons are discussed. An original method for fabrication of ultrasmooth surfaces of beryllium substrates is presented, and limiting roughnesses are reported. Reflectances at a wavelength of 13.5 nm are determined for a multilayer Mo/Si mirror deposited on the beryllium substrate. Prospects for improving quality of polishing of beryllium substrates are discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Emission Properties of Laser Plasma Excited on Molecular-Cluster Carbon Dioxide Jets

We report on the results of investigation of a gas-jet laser-plasma source of extreme ultraviolet radiation based on a conical supersonic nozzle. As a target, we used molecular-cluster CO{sub 2} jets. Different regimes of the gas flow were obtained by varying the gas parameters at the gas inlet and the influence of these regimes on the emission and technical characteristics of the radiation source was analyzed. It has been shown experimentally that radiation emission is intensified upon an increase in the amount of clustered material in the jet.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2019

Influence of Thermal Annealing on the Properties of Multilayer Mo/Be Mirrors

The influence of thermal action on X-ray optics performance and structure of films and transition regions in multilayer Mo/Be mirrors optimized for a reflection maximum in the interval 11.2–11.4 nm at normal incidence has been considered. The annealing temperature reached 300°C and the annealing time was 1 and 4 h. It has been shown that after thermal annealing in vacuum for 1 h at 300°C, the reflection coefficient rises; however, when the annealing time grows to 4 h, it drops. Grains in molybdenum films become finer, and the profiles of transition regions change from exponential to linear. The period of multilayer mirrors has remained the same under all annealing conditions.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Optical, Mechanical, and Thermal Properties of Free-Standing MoSi{sub 2}N{sub x} and ZrSi{sub 2}N{sub y} Nanocomposite Films

The optical, mechanical, and thermal properties of free-standing structures based on nitrided molybdenum and zirconium silicides have been studied. It has been shown that silicide nitriding considerably improves the thermal stability of films. While as-prepared amorphous MoSi{sub 2} and ZrSi{sub 2} films crystallize in the interval 330–370°C, nitriding of films has made it possible to increase their working temperatures in vacuum to 600–700°C (at least, for x ≥ 0.25, y ≥ 1.3). Tensile tests have shown that the ultimate strength of MoSi{sub 2}N{sub x} films (0 ≤ x ≤ 0.55) depends on nitrogen content only slightly. Comparison between the properties of MoSi{sub 2}N{sub x} and ZrSi{sub 2}N{sub y} films magnetron-sputtered at the same partial pressure of nitrogen has demonstrated that with transmission coefficients of films at a wavelength of 13.5 nm being close to each other, ZrSi{sub 2} films are more effective as protection coatings (they are less prone to oxidation and more degradation-resistant).

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2019

Influence of Beryllium Barrier Layers on the Properties of Mo/Si Multilayer Mirrors

The performance of multilayer Mo/Si mirrors with B{sub 4}C and Be spacers near a wavelength of 13.5 nm has been studied. It has been shown that four-component Mo/Be/Si/B{sub 4}C mirrors outperform Mo/Si and Mo/Si/B{sub 4}C mirrors in reflection coefficient by 2.0 and 1.3%, respectively. In addition, Mo/Si mirrors offer the widest transmission band width at half maximum (Δλ{sub 1/2} = 0.535 nm). An explanation for these findings has been given.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Observation of Laser-Induced Spark in the Density Jump in a Gas-Jet Target

In the design of powerful laser-plasma sources of extreme ultraviolet radiation with a gas jet as the target, the problem of degradation of gas nozzles is topical. Degradation is observed due to insufficient distance from the generation zone of the laser-induced spark to the nozzle exit. The comprehensive solution to this problem is proposed by forming the laser-induced spark in the density jumps that are generated upon deceleration of the supersonic gas jet. In such a density jump, the laser-induced spark is obtained and measurements of emission radiation intensity are performed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗