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The paper presents a new instrument—a portable spectroscopic quasi-optical (QO) THz ellipsometer-reflectometer (SQOTER). It combines two independent experimental techniques: THz ellipsometry and reflectometry. SQOTER is based on the hollow dielectric beamguide and beamguide components as a QO transmission line. This ultra-broadband line provides operation of the setup within 0.1…1 THz frequency range. The setup provides measurements of the ellipsometric parameters (at variable incidence angle) and the reflection coefficient (at normal incidence) in the wide spectral range. A detailed analysis of the spectral characteristics of QO transmission line and components was carried out. The principles and details of SQOTER measurements were described and its accuracy was estimated. A special system based on a silicon wafer was created for SQOTER testing. Reflection coefficients of this system measured independently by ellipsometry and reflectometry were compared and showed good agreement. The portable SQOTER capabilities connected with research and industrial applications have been demonstrated.

This work is devoted to the experimental study of the effect of contamination of CFRP plates with silicone release agents on their ellipsometric parameters, and, accordingly, the possibility of ellipsometry to diagnose such contamination. As the studied objects, three series of CFRP samples, consisting of the initial (not contaminated) and contaminated samples, were used. In total, three degrees of contamination (concentration) with silicon were investigated: 5 at.%, 10 at.%, and 20 at.%. We used a quasi-optical sub-terahertz ellipsometer with an operating wavelength of 2.14 mm. It is shown that using sub-terahertz ellipsometry it is possible to reliably determine the concentration of silicon contamination of the CFRP surface. The ellipsometric parameters that are most sensitive to such contamination are determined.

The effect of severe plastic deformation by barocryodeformation at liquid nitrogen temperature on the structure of precipitation-hardened commercial CuCrZr alloy is investigated. In particular, the dependence of the microstructure, the preferential orientation of the crystallites, and the lattice period of the alloy on the deformation degree were studied. The samples were preliminarily water quenched from a premelting temperature to create a supersaturated solid solution of dopants in the copper matrix. It was shown that the evolution of the average size and distribution density of the precipitates with the degree of deformation increase indicates the occurrence of competing processes in the alloy. It was shown that the decomposition of the solid solution due to the strain-induced acceleration of diffusion processes and strain-induced dissolution of the precipitates definitely contribute to the evolution of the structure. The conclusion about the simultaneous occurrence of kinetically opposite phase transformations was confirmed by the observation of a nonmonotonic change in the lattice constant of the matrix and the precipitates density with increasing accumulated deformation.

An algorithm for calculating the number of broken interatomic bonds for a hexagonal close-packed crystal lattice cut by an arbitrary plane is proposed. This challenge occurs in surface energy calculation, modeling strength and surface properties, the crystal growth simulation, and other problems of solid-state and surface physics. The dimension and complexity of this problem are so great that it cannot be solved without involving a computer with a proper software. In the paper, the geometry of the HCP lattice was analyzed. This made it possible to represent the lattice as an integer discrete space and to construct an integer metric in it. Such representation allowed us to develop an exact, fully integer algorithm for solving the problem. The algorithm was implemented as a PC application. In addition to the number of broken bonds, the application calculates the reticular density, builds 3D models of the HCP lattice cross-section by a given plane. The analysis of the time complexity of the algorithm and test results are also given.

The breaking of interatomic bonds occurs when a new crystal surface is formed. Energy expended to form a new surface is called surface energy. Surface energy determines all surface properties of materials. The number of interatomic bonds broken during the surface formation is one of the main parameters which determine the surface energy. This parameter depends on the crystalline orientation of the surface and determines the anisotropy of the surface energy. Calculation the number of broken bonds is a difficult task even for simple lattices and trivial orientations of the section plane. For more complex configurations, this task cannot be solved without a computer. This paper is devoted to the development of algorithms and software for calculating the number of broken bonds of a surface atom of a crystal with a cubic crystal lattice. This makes it possible to calculate the surface energy in the model of broken bonds as a function of the grain orientation, and, hence to predict all surface properties of materials.

The effect of various kinds of severe plastic deformation (equal-channel angular pressing and quasi-hydrostatic extrusion at 77 and 300 K) on the structural formation of precipitation-strengthened CuCrZr alloy has been studied. A combination of experimental methods has been used. Sputtering by deuterium ions was used as the tool for the layer-by-layer study of the alloy structure. The difference between the sputtering yields of the matrix (copper) and precipitates (Cr and Zr) allowed us to visualize the alloy structure to a total depth of 0.5−1 μm. The effect of severe plastic deformation on the precipitate distribution is considered. It has been shown that the main peculiarity of the microstructure is related to the high density of precipitates enriched in chromium, which completely determine the surface roughness. Their distribution is not related to the grain size. The combination of equal-channel angular pressing and quasi-hydrostatic extrusion was shown to lead to the increase in the microhardness of the CuCrZr alloy to 2300 MPa in the case of low-temperature quasi-hydrostatic extrusion (at 77 K) and to the retained high conductivity. It has been proved that the high anisotropy of precipitate shape, microhardness, and sputtering yield of the CuCrZr alloy is determined by equal-channel angular pressing.

A novel experimental setup for multiangular ellipsometric measurements in terahertz spectral range 0.1– $\hbox{1 THz}$ is described. The instrument operates in polarizer-compensator-sample-analyzer configuration and allows various measurement schemes (e.g., null and rotating analyzer). The ellipsometer is based on quasi-optical transmittance line—hollow dielectric beamguide (HDB)—and a kit of HDB-based components that provided main advantages of the ellipsometer as compared with known analogs. HDB provides almost flat phase front of the radiation on the entire channel cross section without any lenses or mirrors. Ultra-broadband quasi-optical transmittance line provides operation of the ellipsometer within 0.1– $\hbox{1 THz}$ frequency range without any modifications of configuration and/or construction. This setup can be assembled/disassembled very easily (as a LEGO meccano) and is easily integrated into other equipment. Experimental testing of the ellipsometer was carried out by comparing dielectric constants of a set of materials measured by the setup with reference data and with the results of independent reflectometry measurements.

This paper is devoted to experimental study of the influence of surface defects such as localized defects specific for polycrystalline materials, subjected to ion sputtering, on optical ellipsometry data. The study was performed using ferrite substrates with ferrite parallelepipeds of different size located in the center of the sample. A quasioptical multiangle terahertz ellipsometer that operates at 2.2 mm (0.14 THz) wavelength was used. Such a large wavelength makes it relatively easy to create structures with known geometric parameters on the surface under study. It is shown that ellipsometry is not sensitive to localized defects in the form of a parallelepiped if its size is comparable or smaller then the wavelength.

Simulation of neutron irradiation and sputtering on ITER-grade tungsten was studied. The effects of neutron-induced displacement damage have been simulated by irradiation of tungsten target with W6+ ions of 20 MeV energy. Bombardment by Ar+ ions with energy 600 eV was used as imitation of impact of charge exchange atoms in ITER. The sputtering process was interrupted to perform in between measurements of the optical properties of the eroded surface and the mass loss. After sputtering was finished, the surface was thoroughly investigated by different methods for characterizing the surface relief developed due to sputtering. The damaging to, at least, the level that would be achieved in ITER does not lead to a decisive additional contribution to the processes under impact of charge exchange atoms only.

Native plant species growing on contaminated sites in an urban environment successfully develop under strong anthropogenic pressure and thereby may have the potential for phytoremediation. The concentrations of potentially toxic metals were measured in leaves, roots, stems, and inflorescences of fifteen Brassicaceae plant species from the urban park of Botanical Garden of Komarov Botanical Institute. The potential of phytoextraction and phytostabilization of the species was evaluated considering the concentration of Cd, Cu, Ni, Pb, Zn in the plant organs, and the bioconcentration factor (BCF) and the translocation factor (TF). The metal content in plant organs varied with plant species. The study of metal accumulation in plants showed that Brassica campestris has the potential for the simultaneous phytoextraction of three metals Zn, Cd, and Cu, and Rorippa palustris – of two metals Zn and Cd. According to received data, species Sinapis arvensis and Thlaspi arvense can be considered adequate candidates for soil Zn and Pb phytostabilization and soil conservation.

This paper is devoted to the study of the effect of surface energy anisotropy on the tungsten surface relief modification under ion sputtering. In our experiments, the sputtering of textured polycrystalline tungsten with Ar ions resulted in a stepped surface relief formation. The surface after sputtering was analyzed using the electron backscatter diffraction and confocal laser scanning microscopy techniques. The formation of the stepped relief is explained by different surface energies of differently oriented grains (surface energy anisotropy). The surface energies of the three low-index W planes were calculated in the model of broken bonds. It is shown for the first time that the ratio of the sputtering depth of differently oriented grains of W is equal to the ratio of the differences of the surface energies of these grains. In that way, the ratio of the sputtering yields of differently oriented grains of tungsten can be quantified by knowing the surface energy, which depended on the reticular grain density and the number of broken bonds with nearest and next-nearest neighboring atoms on the surface using the broken bond model. It is shown that ion sputtering can be used as an instrument for studying the surface energy of solids.

The simultaneous effect of sputtering and neutron irradiation on the optical properties of tungsten mirrors has been considered, which was simulated by bombardment by 20-MeV W+6 ions. The action of charge-exchange atoms was imitated using Ar+ ions with an energy of 600 eV. The dependence of the structure of the surface and optical properties of tungsten on the fluence of Ar ions has been studied using optical microscopy, interferometry, reflectometry, and ellipsometry. It has been shown that irradiation with neutrons should introduce a significant additional contribution to the processes at the tungsten surface that occur under the effect of charge-exchange atoms. An analysis of experimental data obtained by using reflectometry and ellipsometry made it possible to suggest a realistic model of the process of surface modification for samples of ITER-grade tungsten (that were preliminarily irradiated by tungsten ions) using prolonged sputtering by Ar+ ions.

The effect of heavy sputtering and of neutron irradiation simulated by displacement damaging with of 20 MeV W 6+ ions on the optical properties of tungsten mirrors was studied. Ar + ions with 600 eV of energy were used as imitation of charge exchange atoms ejected from fusion plasma. The ion fluence dependence of the surface topography and the optical properties of polycrystalline, recrystallized tungsten (grain size 20–100 μm) were studied by optical microscopy, interferometry, reflectometry and ellipsometry. Furthermore, after sputtering in total a layer of 3.9 μm in thickness, the orientation and the thickness of the eroded layer of many individual grains was determined by electron backscattering diffraction and confocal laser scanning microscopy. Concluding from the obtained data the neutron irradiation, at least at the damage level would be achieved in ITER, has not to make an additional contribution in the processes developing under impact of charge exchange atoms only.

The effect of the structure and size of grains on changes in the microrelief and optical characteristics of specimens of mirrors made of copper alloys with substantially differing grain size upon bombardment by ions of deuterium plasma are studied. Based on a comprehensive study of the structural features of the surface layers of specimens of mirrors made of light copper-chromium alloys, a conclusion is drawn as to the determining role of grain size in their radiation properties.

The surface topography and optical properties of recrystallized tungsten exposed to a low-energy (38 eV/D), high flux (10 22 D/m 2 s) deuterium plasma with an ion fluence of 10 26 D/m 2 at various temperatures was investigated. It was found that the surface morphology weakly depends on the exposure temperature in the range 320–695 K with the exception of the narrow temperature region around 535 K, where large changes to all optical characteristics occurs. After plasma exposure at this temperature, the surface topography of the W sample is characterized by active blistering as has already been indicated in previous publications. The reflectance found in direct measurements at normal incidence drops in the wavelength interval 220–650 nm, whereas the estimations of reflectance using the ellipsometry data demonstrate some increase.

Using ellipsometry and reflectometry, an anomalous change in the optical properties of recrystallized tungsten (W) as a result of bombardment with deuterium (D) ions was discovered at a sample temperature of ∼535 K. There is a qualitative difference between the value of reflectivity obtained from reflectometry measurements and that calculated from the ellipsometric data. A physical model of the discovered effect is proposed. It is shown that two processes take place at the surface of W exposed to plasma at 535 K: the appearance of blisters and a modification of the electronic structure of the surface layer.

Changes in the optical properties of samples of aluminum-alloy mirrors caused by ion bombardment with ions from a deuterium plasma, which imitates conditions that can exist upon the operation of the first mirrors for diagnostics of plasma in an ITER, have been investigated. The basic methods of studying the mirror surfaces were ellipsometry and reflectometry; as an additional procedure, Auger electron spectroscopy was used. It has been found that the coefficient of reflection of mirrors decreases as a result of irradiation by ions with an energy of ∼1 keV, but it can be restored by the subsequent irradiation by ions with a lower energy (∼60 eV). The complex of experimental studies that were performed was used as a base for the selection of a mathematical model for a correct interpretation of ellipsometric data. The results of multiple-angle and spectral ellipsometry were analyzed in terms of the models of a clean surface and single-layer films. On the basis of the analysis of experimental data and simulation of the effective medium, we proposed a mechanism, which explains the results of the experiment; this mechanism is based on (1) the chemical processes in the surface layer in the first cycle of “degradation-restoration” and (2) the development of roughness as a result of a sequence of procedures of “degradation-restoration.”

Field investigations were performed into the nature of oxidation of Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 alloy (Vitreloy-1), a new alloy highly promising for in -vessel mirrors of the ITER (International Thermonuclear Experimental Reactor). The main methods of investigation were X-ray photoelectron spectroscopy and multi-angle ellipsometry. The resistance of the optical properties of Vitreloy-1 against radiation impact was explained by the oxidation of the surface layer, based on the features of the diffusion process in amorphous alloys and of interaction between amorphous metal alloys with hydrogen.

The ion-induced modification of aluminum alloy mirrors, under bombardment by deuterium plasma ions has been investigated as a simulation of the environment effects on in-vessel mirrors in ITER. Ellipsometry and reflectrometry have been used to characterize the mirror surface, along with several surface diagnostic techniques (XPS, Auger, SIMS). The results of multiangular- and spectro-ellipsometry were analyzed using both a bare surface model, and effective medium model; the medium was composed of Al, Al 2 O 3 (Al(OD) 3 or AlOOD), and voids. It was found that the reflectance decreases following exposure to keV-range ions, but can be restored by subsequent exposing the mirror to low-energy ions (∼60 eV). Chemical processes related to an increased oxide layer are thought to be responsible for the decrease in reflectance, while the reduction of the oxide layer following low-energy D + exposure may lead to the return of high reflectance. By comparing the measurements with the results of modeling, a mechanism is suggested to explain the experimental data. The mechanism is based on: (1) chemical processes in a surface layer and (2) сhanges in the thickness and roughness of the surface layer.

The 90° reorientation of Er3+ spins in ErFeO3 have been directly observed using optical spectroscopy. The peculiarities of the absorption spectrum of ErFeO3 in the region of the 4I15/2 → 4F9/2 transition of the Er3+ ion in the temperature range of ac-spin reorientation have been studied. It is shown that the spin reorientation phase transition (SRPT) is accompanied by splitting of the ground and excited states into Kramers doublets in the iron exchange field. This fact is a direct evidence of purely magnetic origin of SRPT. The experimental results were used to analyze the magnetic properties of ErFeO3. This analysis showed that the order of magnitude of the magnetic moment, its variation in the SRPT region, and the existence of Tcomp can be interpreted in terms of the single-ion model, taking into account the influence of the crystal field and the molecular field produced by the iron subsystem ions.

In-vessel mirrors are necessary for optical diagnostics of plasmas in next-step fusion devices. These mirrors will be under the influence of the harsh fusion environment, and in these conditions th...

The rearrangement of domain structures in erbium orthoferrite plates with a hard-magnetic surface layer has been visually investigated and explained on the basis of proposed physical models. It is shown that, when the temperature of such plates approaches the temperature range of spin reorientation, the surface energy density of the domain walls separating the internal and surface domains decreases, resulting in a transition to domain structures that are close to equilibrium.

In this paper the results of post-mortem analysis of mirror samples (molybdenum, stainless steel and copper) exposed for the 1 year experimental campaign inside the Tore Supra tokamak are presented. The mirrors were not protected during the experiment and therefore were exposed both to glow discharge conditioning of the vessel walls and to working discharges. After exposure, all samples were found to be eroded and at the same time were coated with a thin contaminating deposit. We pay attention to the fact, that the observed erosion cannot be described using the published sputtering yields. In particular, the difference between the erosion of stainless steel and copper exceeded a factor of 10 and the difference between the erosion of stainless steel and molybdenum was less than a factor of 2 in comparison with the corresponding factors of approximately 2.5 and apprximately 10 known from the literature. An attempt is made to correlate these observations with the different sticking coefficients of carbon on ...

An intermediate state revealed upon a first-order metamagnetic phase transition in a magnetic field aligned parallel to the Ising c axis of Er3+ ions in crystals of erbium ferrite ErFeO3 at a temperature of 1.6 K is visualized for the first time. The region of existence of the intermediate state and the parameters of the domain structure are determined, and the possible conditions providing for visualization of the intermediate state and its specific features are analyzed. A thermodynamic model is proposed for the stabilization of the intermediate state. It is shown that theoretical results are in good agreement with experimental data.

In-vessel mirrors are necessary for optical and laser diagnostics of plasmas in next-step fusion devices; however obtaining mirror materials that will maintain their performance in the harsh fusion environment remains problematic. At present, mirrors are fabricated from polycrystals or monocrystals, and metal films on metallic substrate mirrors are also being studied. In this paper, we report on a new family of bulk amorphous alloys that are being investigated in the search for new materials for the fusion environment. Their properties are very different from properties of well-known materials and are insufficiently investigated for scientific and technological applications. We present the results of investigation of modification of the surface and optical properties of amorphous mirror fabricated from Zr(41.2%)Ti(13.8%)Cu(12.5%)Ni(10%)Be(22.5%) alloy after bombardment by ions of deuterium plasma with different fluence and energy.

During the third experimental campaign, three stainless steel mirrors were exposed inside the Large Helical Device (LHD) vacuum vessel and, in order to measure the change in their spectral reflectance R(λ), the effect of this exposure was measured at normal incidence (λ=200–700 nm). The mirrors located in the divertor region and in the diagnostic port became coated with carbon-based films; however, the mirror placed closest to the plasma confinement volume became cleaner than it had initially been. The characteristics of the films were obtained by different techniques. The deposited films were slowly removed by repeatedly exposing the mirrors to low-energy ions of deuterium plasma, and R(λ) was measured after every exposure. In the present paper we compare the reflectance behaviour during this cleaning procedure and the reflectance calculated in the framework of a model assuming that a half-transparent film is formed on stainless steel substrate. The n(λ) and k(λ) data for carbon-based films were taken fr...

Experiments have been performed to evaluate the changes in surface structure and the resulting effects on the optical properties of stainless steel due to hydrogen ion irradiation. Stainless steel (SS) is a standard material used for in-vessel components, including the first mirrors (FMs), in some current generation fusion devices. Optical microscopy, interferometry, scanning electron microscopy (SEM) and ellipsometry were used to characterize the surfaces. Results are presented for the bombardment of SS mirrors with H 3 + ions having various fixed energies (0.3, 0.65, and 1.5 keV/H+), with ion flux densities of (0.5–2) × 1020 H+/m2s and fluences of ∼2.2 × 1024 H+/m2. Variation of the ion energy at a constant fluence had a considerable effect on the damage structure that forms on the SS mirror surfaces. Possible mechanisms for the ion energy effect on the surface are discussed and a model of the damaged surface layer is proposed.

Surface roughening of polycrystalline stainless steel mirrors due to hydrogen bombardment was studied as a function of ion fluence and energy (1–4.3 × 10 24 H/m 2 , 300–1500 eV/H). A strong micro-relief (100 nm scale) on single grains and a strong variation of the erosion depth between different grains were observed by scanning electron microscopy (SEM). A broad variation of the in-grain micro-relief was found to be independent of impact energy. The sputtering yield (Y) depends on the grain orientation, varying by a factor of about 2 for all impact energies. The correlation between surface morphology and orientation of the single grains was investigated using electron back-scattering diffraction (EBSD). Grains with nearly (1 1 1) surface orientation do not show any significant in-grain micro-relief, although they have nearly the highest Y. For other orientations close to low indexed surfaces, e.g., (3 1 1), no correlation was found between Y and roughness.

A system for automating ellipsometric measurements on the basis of a cryogenic spectral null-ellipsometer is described. Three step motors imitating a manual method are used as actuators. A digital voltmeter serves as a measuring device. The system operates under the control of a computer and contains a minimal number of nonstandard parts. The accuracy characteristics of the ellipsometer are improved due to algorithmic methods: an adaptive method used to seek zero makes it possible to eliminate fluctuation errors by time averaging. The automation system described is a fairly universal means of communication between a computer and an experimental setup and can be applied in other physical experiments.

Magnetic flux spatial distribution patterns in the single crystal YBa 2 Cu 3 O 7− x placed into homogeneous magnetic field in the temperature range 5 K T T c were compared with twin structure peculiarities. It is shown that twin boundaries do not effect the flux structure formation at low temperatures, but their effect becomes dominant at higher temperatures. The obtained results indicate the existence of two vortex pinning mechanisms in YBa 2 Cu 3 O 7− x single crystals.

A magneto-optical high resolution technique is described which uses Bi-containing ferrogarnet film as an indicator. The technique was used to visualize and make topograms of the magnetic flux distribution in the vicinity of high temperature superconductors over a wide range of temperatures (5–300 K) and magnetic fields (0–35 kOe). It is shown that analysis of the visual patterns may be helpful in studying the specific processes of interaction between the magnetic field and the high temperature superconducting samples. The distribution of magnetic flux density in the samples was found and structure defects revealed. In addition, the important macroscopic parameters, such as superconducting transition temperature, temperature dependence of the lower critical field, critical current density and volume pinning force, were estimated. Application of the technique for rapid analysis of high T c superconducting materials quality is substantiated.

An experimental solution to the problems of cooling and reliable temperature measurement on samples mounted in vacuum on the cold source in an optical cryostat is advanced and substantiated scientifically. Two typical cases are considered, which differ fundamentally in the sources and heat influxes to the sample, as well as in the mechanical contacts between the sample and cold source. The realistic models of thermal balance developed for the optical elements of the cryostat give rise to numerical estimations consistent with experimental results.

Two plasma diagnostics in ITER will use cube-corner reflectors (CCR): poloidal polarimetry and toroidal interferometry/polarimetry. The multichannel poloidal polarimetry system is planned to operate at a wavelength of 118.8μm. The multichannel toroidal interferometry/polarimetry system is based on a CO2 laser operating at wavelengths of 10.6 and 9.27μm. The long term sputtering by charge exchange atoms and/or deposition of carbon-based (or beryllium-based) contaminant layers can affect the optical properties of the CCR. The role of both these potentially deleterious effects on the CCR operation is analyzed in this article, taking into account the probing beam wavelength and the CCR locations. The conclusion is that for the intended use of a CCR in the poloidal polarimetry at 118μm neither erosion nor deposition should pose a problem. On the other hand, in the toroidal interferometry/polarimetry system operating at 10μm, care must be taken to reduce the charge exchange atom flux and it is likely that depos...

The lifetime of refractive components exposed to reactor grade plasmas will be very short and so all diagnostics which use UV (λ > 5nm), Visible and IR radiation (λ up to ∼100μm) have to view the plasma via a mirror. The diagnostic first mirrors (FM) must survive in extremely hostile conditions and maintain a good optical performance for the duration of reactor operation. In ITER-FEAT the FMs will receive intense UV and X-ray radiation, neutron and gamma fluxes, and particle fluxes (due to charge exchange atoms (CXA)). In addition, they will be subjected to the deposition of material eroded from the divertor and first wall. Of the different kinds of radiation and fluxes only CXA impact will result in direct surface modification of metallic FMs that can lead to degradation of optical properties. The fluxes of all radiation components to the mirror surface depend strongly on the mirror location. For example, the FMs of a wide-angle observation system (endoscope with open architecture) in ITER will be bombarded by CXA fluxes of about the same magnitude as the first wall. On the other hand, the FMs in the LIDAR system are located in a long duct (∼2 m in length) and will receive CXA fluxes ∼ 10−2 of the first wall flux. This corresponds to about the lowest flux received by a FM in ITER.

Simultaneous effects of neutron irradiation and long–term sputtering on the surface relief of ITER–grade tungsten were studied. The effects of neutron–induced displacement damage have been simulated by irradiation of tungsten target with W6 + ions of 20 MeV energy. Ar+ ions with energy 600 eV were used as imitation of charge exchange atoms in ITER. The surface relief was studied after each sputtering act. The singularity in the WJ–IG surface relief was ascertained experimentally at the first time, which determines the law of roughness extension under sputtering. As follows from the experimental data, the neutron irradiation has not to make a decisive additional contribution in the processes developing under impact of charge exchange atoms only.

The review describes several cryostat designs for spectral and magneto-optical studies representing continuous flow systems with sample cooling by preset temperature vapour blow-over. The characteristic features and advantages are discussed. It is shown that among present-day heat transfer methods, this one is the most efficient for studies involving appreciable heat influx to the cooled sample.

The effects of hydrogen ion (H3+) bombardment on the optical properties of polycrystal stainless steel (SS) mirrors were investigated. Ellipsometry, profilometry, scanning electron microscopy, angle distribution of scattered light, and spectral reflectance were used to characterize the surfaces. Results for the bombardment of SS mirrors with ions of fixed energy (0.3, 0.65 and 1.5 keV/H), with ion flux density (0.5–2) · 1020 H/m2s up to fluences of (1.1–4.3) · 1024 H/m2 are presented. The data show that the surface roughness rises with both increasing ion energy and ion fluence, and that surface roughening leads to an increase of the scattered light with a corresponding decrease of reflectance at normal incidence. The thickness of the apparent layer, obtained by ellipsometry, was found to rise with increasing ion energy at fixed ion fluence and with increasing ion fluence at fixed ion energy. Possible mechanisms for the ion energy effect on the degradation rate of stainless steel mirrors and the origin of the apparent layer are discussed.

An insert which has a vapour pumping system for a liquid cryostat used for spectral and magneto-optical studies is described. Temperatures in the range 4.2 to 300 K are achieved by forced bathing the specimen with a stream of vapour at the given temperature.