The results of a study of the structural and reflective characteristics of short-period multilayer X-ray mirrors based on Mo/B 4 C at wavelengths 1.54 Å, 9.89 Å and 17.59 Å are presented. The period of the samples varied in the range 8–35 Å. The average widths of the interfaces were ∼3.5 and 2.2 Å at one and the other boundaries, with a tendency for weak growth with any decrease in the period. The interlayer roughness was ∼1 Å. The research results indicate promising prospects for the use of multilayer Mo/B 4 C mirrors for synchrotron applications.

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.

The study of chemical interactions between Mo and B4C layers in multilayer structures depending on their total thickness (d) and thickness ratio (Gamma) was carried out using X-ray photoelectron spectroscopy (XPS) method. The results showed significant interactions of materials within the multilayer structures. Specifically, in the range of d from 1.8 to 3.4 nm and Gamma value between 0.24 and 0.46, a complete conversion of B4C into MoBxCy was observed, while retaining some amount of molybdenum. The insertion of tungsten barrier layer to the Mo-on-B4C interface led only to insignificant reduction of component MoBxCy. Based on the data obtained by XPS, theoretical models were developed and applied to X-ray reflectometry data during fitting procedure. The application of XPS has proven to be highly effective in constructing models and obtaining numerical values when fitting reflection curves.

Promising wavelengths for next-generation lithography with a wavelength shorter than 13.5 nm based on a synchrotron X-ray source are discussed. Theoretical and experimental values of the reflection coefficients of multilayer X-ray mirrors providing the maximum reflectivity in the range of 11.4-3.1 nm are presented. The theoretical efficiency of multilayer optics is compared for different wavelengths. Keywords: X-ray lithography, multilayer X-ray optics, multilayer X-ray mirrors.

The paper presents the results of studies of W/B4C multilayer structures with small periods for their use as the first mirror in a two-mirror soft X-ray monochromator at the KOSMOS station of the VEPP-4M synchrotron. It is shown that even if the periods of the mirror and the RbAP crystal coincide, when operating in a wide wavelength range, the Bragg angle must be adjusted due to the stronger refraction in the W/B4C multilayer mirror.

The reflective and structural parameters of Be/Si/Al multilayer mirrors have been studied. The extent of stability of their X-ray optical characteristics has been demonstrated during storage in air for 4 years and during vacuum annealing at temperatures up to 100°C. A high reflectance of 62.5% was obtained, together with a spectral selectivity of λ/Δλ≈59 at a wavelength of 17.14 nm and 34%, with λ/Δλ ≈ 31 at a wavelength of 31.3 nm. It was shown that Si interlayers reduce the interlayer roughness from 0.45 to 0.20 nm.

This study investigates mechanical stresses in Mo/Be/Si multilayer mirrors. We determined layer thicknesses (for Si-1.0 nm, Mo-2.8 nm and Be-3.2 nm) in the period that simultaneously provided high reflection coefficients (R-66-67%) at a wavelength of 13.5 nm with zero internal stress values. At the wavelength of 13.5 nm, the reflection coefficient of a stressless Mo/Be/Si multilayer mirror deposited on a micro-electro-mechanical system of micromirrors had a value of about 23% with a reflection from the witness of 67%. An interferometric method for determining the stress values in films, which is able to provide a measurement accuracy at the level of Delta s +/- 0.24 MPa, is described in detail.

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.

The results of investigations of Ru/Sr multilayer coatings optimized for the spectral range of 9-12 nm are presented in this Letter. Such mirrors are promising optical elements for solar astronomy and for the development of beyond extreme ultraviolet (BEUV) lithography. A near-normal incidence reflectivity of up to 62.3% (λ = 11.4 nm) right after the synthesis is measured. The reflection coefficient decreases to 56.8% after five days of storage in air with a subsequent stabilization of its value. At a wavelength of λ = 9.34 nm, the reflection coefficient is 48.6% after two months of storage in air. To date, to the best of our knowledge, this is the highest reflectivity measured in this spectral range. The possibility of further increasing the reflectivity is discussed.

Ru/Y multilayer mirrors for a wavelength range of 8–12 nm are studied. A positive effect of the use of B 4 C barrier layers on the reflectance is shown. A record reflectance of 56% at a wavelength of 11.4 nm was achieved on a Y/B 4 C/Ru mirror.

The results of the investigation of the dense ECR discharge hydrogen plasma flux formation in the magnetic field of a single solenoid are presented in this work. The transversal flux profile obtained at the optimal system parameters is shown. The possibility of the formation of homogeneous plasma fluxes with density of 750 mA/cm 2 and total current of 5 A is demonstrated. The results of the first experiments of the hydrogen ion beam extraction from the ECR discharge plasma in the single magnetic coil are presented. The record values of the ion current density higher than 1.5 A/cm 2 were obtained. The results of the research presented in this paper show the prospects of the proposed system for applications such as the neutral beam injector development for the plasma heating in the controlled fusion facilities.

The results of studies of Ru/Sr multilayer mirrors optimized for the working wavelength range of 9-12 nm are presented in the paper. Within the framework of the presented article the strontium based multilayer structures with stable over time reflective characteristics were obtained for the first time. It is shown that Ru/Sr mirrors have the highest reflectance of all known reflective coatings, with the exception of beryllium-containing, in the spectral range of 9-12 nm.

The results of studies of Ru/Sr multilayer mirrors optimized for the working wavelength range of 9-12 nm are presented in the paper. Within the framework of the presented article the strontium based multilayer structures with stable over time reflective characteristics were obtained for the first time. It is shown that Ru/Sr mirrors have the highest reflectance of all known reflective coatings, with the exception of beryllium-containing, in the spectral range of 9-12 nm. Keywords: multilayer X-ray mirrors, X-ray lithography, X-ray radiation.

The results of the investigation of the reflective characteristics of multilayer mirrors based on Ru/Y are presented. Reflection coefficients at the level of 38.5% at an operating wavelength of 9.4 nm. It is shown that the deposition of B4C barrier layers onto Y layers makes it possible to significantly increase the reflection coefficient compared to structures without barrier layers. A reflectance of 54% was obtained for mirrors optimized for 11.4 nm, which is close to the theoretical limit for these materials.

Promising wavelengths for next-generation lithography with a wavelength shorter than 13.5 nm based on a synchrotron X-ray source are discussed. Theoretical and experimental values of the reflection coefficients of multilayer X-ray mirrors providing the maximum reflectivity in the range of 11.4-3.1 nm are presented. The theoretical efficiency of multilayer optics is compared for different wavelengths.

Measurements of the reflection coefficient angular dependency for an MLM, performed using a laboratory reflectometer (curve with symbols)

In this paper we report on a high current density ion beam profile diagnostics with a slit-based system as a reliable method, capable of high thermal load applications. The task arose in frames of a point-like neutron source development for neutron radiography. In previous research, it was suggested to construct such a system as a D-D neutron generator based on the high current gasdynamic ion source, which utilises the plasma of electron cyclotron resonance discharge sustained by powerful millimeter wave gyrotron radiation. This device is able to produce focused D+ beams with a characteristic diameter of 1 mm, total current above 100 mA, and current density at a level of several A/cm^2. Study of such intense beams profile to obtain the best focusing efficiency and minimize neutron producing area appeared to be a challenging task. The paper also demonstrates the possibility of fast neutron imaging with a point-like powerful neutron generator (neutron yield on the level of 10^10 1/s).

We report on a successful test of a new method for intense ion beam formation using an extraction with inhomogeneous electric field. Its key feature is a special shape of the extraction electrodes providing a higher rate of ion acceleration. It is applicable to any ion source type and could be used to improve performance of a wide range of plasma devices. The proof of concept was carried out using a high-current electron-cyclotron resonance ion source SMIS 37. High efficiency of the new extraction and proton beam formation with a record current density of up to 1.1 A cm-2 was demonstrated.

This paper presents a study of plasma flux characteristics flowing out from the gas-dynamic mirror trap along the magnetic field lines to a metal wall. The main feature of the current work is that the effect of ion acceleration by ambipolar potential is considered in the expander region. The developed model also takes into account a possibility of transition from the collisional expansion of electron flow in the vicinity of the magnetic plug to the collisionless regime. The developed model allows calculation of the ambipolar potential profile and plasma characteristics in the expander region.

The paper presents recent results of a "pointlike" neutron source development based on a D-D fusion in a D-loaded target caused by its bombardment with a sharply focused deuterium ion beam. These developments are undergoing at the Institute of Applied Physics of Russian Academy of Sciences in order to study a possibility to create an effective and compact device for fast-neutron radiography. The last experiments with a beam produced by a gasdynamic high-current ECR ion source and its focusing with a magnetic lens demonstrated that 60 mA of deuterium ions may be constricted to a transversal size of ∼1 mm at the focal plane. With a purpose to improve this result in terms of the beam current and its size, a combined electrostatic and magnetic focusing system is proposed and analyzed. It is shown that the combined system may enhance the total beam current and reduce its footprint down to 0.13 mm. All numerical analysis was performed using the IBSimu code.