It is shown that the use of traditional multilayer X-ray Pt/C mirrors with a periodic gradient only along the direction of propagation of the central X-ray beam, so-called Goebel mirrors, with a source based on the inverse Compton effect, leads to a significant loss of reflected intensity. The efficiency of such mirrors will be about 2% of the total power of the source. To solve this problem, a new approach is proposed based on the use of a set of multilayer mirror strips with different profiles, widths, and periods determined by the parameters of the incident radiation. This work describes the method proposed by us for calculating the period distribution over the mirror surface. The calculation parameters are: the angular dependence of the source photon energy, the mirror size, the distance from the source to the center of the mirror, and the central angle of incidence of radiation on the mirror. The developed method for calculating the periods of a multilayer X-ray mirror is demonstrated by the example of solving a specific problem of X-ray reflection from a source based on the inverse Compton effect, considered earlier in publications. It is noted that in order to apply the technique described in the article when constructing mirrors, it will be necessary to resort to lithography, since obtaining a set of mirrors described in the work using magnetron sputtering seems to be extremely difficult to implement.

The article considers broadband multilayer X-ray mirrors based on Mo/Be and Mo/Si structures with a transmission band coinciding with the Si Lα (13.5 nm) and Sn (13.5 nm) emission lines. The described structures are of great interest for the currently developed liquid source of EUV radiation, since they make it possible to increase the efficiency of the source-X-ray optical system due to the "complete" capture of emission lines. Keywords: extreme ultraviolet radiation, emission spectrum, laser spark, multilayer X-ray mirror.

The work is devoted to the development, fabrication and analysis of broadband W / Si multilayer mirrors for a broadband monochromator, calculated for the spectral range of 7-10 keV. The possibility of using the stacking approach to obtain multilayer mirrors with a reflection coefficient of about 30% and a spectral bandwidth Delta E/E of about 20% is shown. The results of measurements of the angular and spectral reflection curves of the mirror obtained on a laboratory diffractometer and on a synchrotron in Novosibirsk are presented. Keywords: hard X-ray range, monochromator, synchrotron radiation, broadband mirrors, stack structures, multilayer X-ray mirrors.

The properties of Mo/B4C multilayer X-ray mirrors with periods of 3.74–3.84 nm are studied in this work. The dependences of the transmission band, reflection coefficient and the magnitude of internal stresses in mirrors on the ratio of material thicknesses in the period were investigated. The results of a study of the effect of thermal annealing on the structural parameters and reflective characteristics of mirrors are also presented in the paper.

Some variants of the composition of multilayer absorption film filters with a high transmittance in the spectral region of the "water window" (2.3-4.4 nm) have been considered. Having created an ultimate pressure difference between the sides of free-standing films at which they are damaged, we compared the strength of 100 nm thick Ti-based multilayer filters with Al, Be, C interlayers and 100 nm thick V-based multilayer filters with Al interlayers. Sc and Cr was also considered as interlayers. Among the tested periodic multilayer structures, the best strength characteristics were demonstrated by Ti/Be (with a fraction of Ti in a period of about 0.6) and V/Al (with a fraction of V in a period of about 0.4) multilayer filters. Despite the fact that Ti/Be and V/Al filters are inferior in strength to Ti and V monolayer filters of the same thickness, these multilayer filters may be of interest, since they have either a higher transmittance in the "water window" (Ti/Be) or more high level of blocking of visible radiation (V/Al). Keywords: spectral region of the "water window" multilayer free-standing filters, ultimate pressure difference, film filter strength, transmittance in the soft x-ray, visible light blocking level.

Multilayer interference structures acting as dispersion elements for a mirror spectrometer for a wavelength range of 7–30 nm have been calculated and synthesized. Three elements are implemented: for the range λ = 7–12 nm – multilayer structure Mo/B4C (number of periods N = 60, period thickness d = 6.5 nm); for the range λ = 11–18 nm – Mo/Be (N = 50; d = 9.83 nm) and for the range λ = 17–30 nm – Be/Si/Al (N = 40; d = 18.2 nm). For the entire spectral range, an efficiency of more than 10

We report fabrication and testing of a transportable version of a high-resolution flat-field spectrograph. The device uses two replaceable grazing-incidence VLS gratings with central densities of 1200 and 2400 lines mm-1, producing a flat field in the wavelength ranges of 5-28 nm and 2.5-14 nm, respectively. The plate scale is about 0.56 and 0.28 nm/mm at a wavelength of 12 and 6 nm for the first and second gratings, respectively. The VLS gratings are fabricated by interference lithography. The grating efficiency at a wavelength of 12.5 nm is measured by a reflectometer with a laser-plasma source of soft X-ray radiation. During the tests of the spectrograph, line spectra of multiply charged ions in a plasma excited by nanosecond laser radiation are obtained. The spectrograph is designed to record soft X-ray radiation excited by a multiterawatt femtosecond laser in various targets.

Record reflectivity’s of R EXP =23.8% at 3.14 nm and R CALC =30.8% at 3.12 nm have been obtained for Cr/Sc mirrors. Such increases in reflection are the result of decreases in mixing of the system layers with each other due to the use of interface-engineering methods – passivation of the already deposited Cr layer with nitrogen before deposition of the subsequent Sc layer. However, it has been found that adding additional B 4 C layers to such a system leads to a decrease in reflectivity.

The paper reports on a new Zr/Be/Si/Al multilayer structure that provides record reflectances of up to 67% and a spectral resolution of triangle lambda = 0.63 nm (lambda / triangle lambda approximate to 27) in the spectral range of 17-20 nm. It is shown that the structure has a high temporal stability of extreme ultraviolet (EUV) optical characteristics. This fact makes the structure promising for future missions to study the solar corona. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

Blazed and low-roughness 500 lines/mm diffraction gratings, designed for operation in high orders in the soft X-ray and extreme UV (EUV) radiation ranges and having Au and multilayer Mo/Si coatings, have been fabricated by wet anisotropic etching of Si(111)4° vicinal wafers and investigated by atomic force and scanning electron microscopy. The diffraction efficiency of the gratings was determined both using a laboratory reflectometer and by modeling based on a rigorous method of boundary integral equations in the PCGrate™ code, taking into account realistic groove profiles. The diffraction efficiency values measured in unpolarized light with wavelengths of 13.5 and 4.47 nm and the calculated values, found with allowance for random roughness, are almost the same. The absolute efficiency of the grating with a multilayer (five Mo/Si bilayers) coating with a period of 20 nm is 40

The X-ray optical and mechanical properties of dielectric multilayer mirrors based on pairs of C/Si and B4C/Si materials are synthesized and studied. The mirrors are optimized for a wavelength of 13.5 nm. Parameters of the deposition process that simultaneously ensure the fulfillment of three conditions are found: relatively high reflection coefficients at the operating wavelength, near-zero mechanical stresses in the film, and the absence of electrical conductivity. At zero internal stresses, the reflection coefficient of C/Si multilayer mirrors deposited onto superpolished silicon substrates at an operating wavelength of 13.5 nm is R = 11

We describe results of studying emission spectra of Cl-, Br-, and I-containing liquid jet targets in the 3‒6.5 nm wavelength range under their excitation by a pulsed laser. A number of emission lines of Cl, Br, and I ions are recorded, including in the “water-window” spectral range of 2.3‒4.4 nm. A specially developed system based on an industrial pulse valve is used for a liquid-jet target to be formed. The targets are excited by an Nd:YAG laser (λ = 1064 nm, τ = 5.2 ns, E pulse = 0.8 J). Using a Bragg spectrometer based on a multilayer X-ray Cr/Sc mirror and Ti/Be absorption filters, absolute intensities of some of the most intense lines are measured. High emissivity of liquid targets is demonstrated; thus, for a bromine-containing target in the 6.12 ± 0.05 nm band, the resulting radiation intensity in the half-space is 1.3 × 10 13 photons per pulse.

The properties of Mo/B4C multilayer X-ray mirrors with periods of 3.74 – 3.84 nm are studied in this work. The dependences of the transmission band, reflection coefficient and the magnitude of internal stresses in mirrors on the ratio of material thicknesses in the period were investigated. The results of a study of the effect of thermal annealing on the structural parameters and reflective characteristics of mirrors are also presented in the paper.

Multilayer interference structures acting as dispersion elements for a mirror spectrometer for a wavelength range of 7-30 nm have been calculated and synthesized. Three elements are implemented: for the range λ=7-12 nm – multilayer structure Mo/B4C (periods N=60; period thickness d=6.50 nm); for the range λ=11-18 nm – Mo/Be (N=50; d=9.83 nm) and for the range λ=17-30 nm – Be/Si/Al (N=40; d=18.2 nm). For the entire spectral range, an efficiency of more than 10% was obtained at a wavelength resolution of 0.15-1.0 nm.

The paper presents experimental data on the absolute values of the radiation intensity in the wavelength range of 6.6-32 nm for a stainless steel target excited by a Nd: YAG laser with parameters λ=1064 nm, Epulse=0.45 J, tau=4 ns, ν=10 Hz. The results are of interest for various applications using laboratory laser-plasma sources of soft X-ray and extreme ultraviolet radiation. Keywords: extreme ultraviolet radiation, emission spectrum, laser spark, multilayer X-ray mirror.

Some variants of the composition of multilayer absorption film filters with a high transmittance in the spectral region of the “water window” (2.3–4.4 nm) have been considered. Having created an ultimate pressure difference between the sides of free-standing films at which they are damaged, we compared the strength of 100 nm thick Ti-based multilayer filters with Al, Be, C interlayers and 100 nm thick V-based multilayer filters with Al interlayers. Sc and Cr was also considered as interlayers. Among the tested periodic multilayer structures, the best strength characteristics were demonstrated by Ti/Be (with a fraction of Ti in a period of about 0.6) and V/Al (with a fraction of V in a period of about 0.4) multilayer filters. Despite the fact that Ti/Be and V/Al filters are inferior in strength to Ti and V monolayer filters of the same thickness, these multilayer filters may be of interest, since they have either a higher transmittance in the “water window” (Ti/Be) or more high level of blocking of visible radiation (V/Al).

Using a multilayer mirror spectrometer of the extreme ultraviolet (EUV) range, the laser plasma emission spectra of bulk aluminum in the wavelength range of 8.0-18.0 nm were studied. Testing of thin film laser targets made of aluminum and comparative measurements of the intensity of EUV radiation of a film with a thickness of 100 nm and a bulk material target were carried out.

The article considers broadband multilayer X-ray mirrors based on Mo/Be and Mo/Si structures with a transmission band coinciding with the Si Lα (13.5 nm) and Sn (13.5 nm) emission lines. The described structures are of great interest for the currently developed liquid source of EUV radiation, since they make it possible to increase the efficiency of the source-X-ray optical system due to the “complete” capture of emission lines.

The structural inhomogeneities of silicon films embedded within W/Si multilayer mirrors were studied by X-ray reflection, grazing-incidence small-angle X-ray scattering (GISAXS) and X-ray photoelectron spectroscopy (XPS). In the diffuse scattering spectra, evidence of laterally and vertically ordered in-layer inhomogeneities was consistently observed. In particular, specific substructures resonant in nature (named here `ridges') were detected. The properties of the ridges were similar to the roughness determined by quasi-Bragg peaks of scattering, which required a high interlayer correlation of particles. The XPS showed the nanocrystalline nature of the Si particles in the amorphous matrix. The geometric characteristics and in-layer and inter-layer correlations of the nanoparticles were determined. In GISAXS imaging, the unusual splitting of the waists between the Bragg sheets into filament structures was observed, whose physical nature cannot yet be explained.

A project of an X-ray monochromator for the «SKIF» synchrotron based on two flat mirrors with multilayer reflective coatings is reported. The concept of the monochromator is based on the absence of precision mechanical systems and feedthroughs in vacuum, which significantly reduces mirror surface contamination and increases scanning accuracy. In addition, the overall structure of the device is greatly simplified in this way, which in turn leads to a significant reduction in the total cost and labor for manufacturing. The grazing angle of incidence of radiation on the mirrors in the process of scanning by photon energy varies within 0.5-1.3º. The length of the mirrors is 120 mm, the assumed size of the input beam is 1×1 mm2. A wide operating energy range, 8-36 keV, is achieved through the use of 3 strip-mirrors with coatings of different chemical composition, namely: Mo/B4C, W/B4C and Cr/Be. The article presents the X-ray optical scheme, the expected reflection coefficients and spectral selectivity of the monochromator, the results of the calculation of thermally induced surface deformations and the corresponding slope errors of the first mirror.