Leucosapphire (c-LS) structure and transmission in visible after surface treatment in 90%H2-10%N2 RF discharge are studied. According to AFM, the number of scratches of the mechanically polished surface decreased significantly after removal of about a 300 nm layer (exposure time of 12 h) under unchanged rms of roughness. According to TEM, a two-layer structure formed in the near-surface region consists of an outer 10 nm amorphous layer followed by a crystalline layer of 40–50 nm with a high defect density. The c-LS transmission in the angle of 400–1000 nm either slightly increased or remained unchanged. The demonstrated transmission stability during exposure in 90%H2-10%N2 RF discharge allows us to consider the plasma sputtering as a promising technique for cleaning contaminated windows protecting first mirror of divertor Thomson scattering being developed for ITER divertor.

The effect of a cleaning discharge plasma on the KU-1 optical quartz surface topography and transmission in visible and near IR ranges (400-1000 nm) was studied. For the study, we used crossed DC and RF discharges in D2 and D2/N2 mixture, where the N2 fraction was ~25 mol %. The addition of nitrogen increased sputtering rate from 250 to 1200 nm / h while maintaining stoichiometry of the surface layers. The rms surface roughness decreased after the plasma exposure from 1.3 to 0.6 nm, while the quartz transmittance has not changed. The surface roughness analysis and calculation of diffusion scattered light at 400 nm transmitted through the quartz were performed using the power spectral density function of AFM.

An investigation of the products of wear (sludge) formed during fine diamond-abrasive polishing of ruby showed that the sizes of the particles split off the worked surface depend strongly on the properties of the surface-active components of the polishing composition. The results obtained must be taken into account in the development of polishing compositions making it possible to increase the productivity of fine abrasive machining and improve the surface quality of articles.

When surfactants are present in polishing compositions severe damage is done to the initial crystal structure of a very thin (tenths and hundredths of a micron thick) surface layer of the material (silicon) being processed and the deformation-strength properties of the material change as a result of the Rebinder effect. The use of active additives in polishing compositions, including unconventional ones, makes it possible to decrease the thickness of the damaged layer by a factor of 1.5 – 2, significantly increasing the polishing efficiency in the process.

Исследованы особенности окисления вольфрама в О2 или в смеси О2/Н2 в проточном тлеющем разряде с полым катодом в областях катода, плазмы и послесвечения (Т = 300–350 К). Анализ структуры и состава образцов с помощью ДБЭО, ДРЛО, РСМА и РФЭС показал, что поверхность металла после экспозиции в разряде и выдержки на воздухе покрыта тонкой пленкой (5–10 нм) аморфного пористого гидратированного оксида вольфрама WO3. Изучение состава пленки с помощью времяпролетной масс-спектрометрии показало, что пленка WO3 состоит из кластеров (WO3)n (n = 1–6) и молекул воды, адсорбированных в порах. После экспозиции поликристаллов в катоде в разряде О2/Н2 было обнаружено интенсивное селективное окисление отдельных зерен при очень слабом окислении окружающих. Толщина пленок WO3 на соседних зернах различалась более чем в десять раз. Сильно окисленные зерна могут быть источником вольфрамовой пыли в плазменных установках.

Because of the requirement of eliminating carbon deposition on mirrors that facilitate optical methods of plasma diagnostics in thermonuclear synthesis devices, the experimental study has been carried out of gasodynamic conditions and the relationship between the partial flows of hydrogen and methane, which are supplied to the direct current glow discharge. The formation of hydrocarbon deposits would be completely suppressed under these conditions. The processes of methane conversion in the discharge into heavier volatile hydrocarbons have been analyzed by mass spectroscopy and conversion into polymer-like a-C:H films have been analyzing by weighing and electron probe microanalysis. The degree of methane conversion was continuously decreasing upon the dilution of methane with hydrogen. The deposition was suppressed completely when methane concentration in the laminar flow of the mixture was approximately 1 mol %. The process of deposition of a-C:H films changed into the process of film erosion when methane content in the mixture was below 0.5 mol %, the Knudsen number Kn ≈ 0.1, and the Reynolds number Re ≈ 2. In order to provide the removal of plasmolysis products from the surface of the mirror located in a special diagnostic port of ITER, the specified gasodynamic conditions created by the carrier gas (hydrogen or deuterium) should be ensured, with the component of the velocity vector being directed at an angle to the surface under protection.

The mechanism of superhydrophobicity is discussed for coatings based on boron nitride nanotubes, i.e., on a material with high surface energy. It is shown that the thermodynamic stability of the superhydrophobic state is related to a surface roughness determined by nanotube packing and a decrease in surface energy due to the adsorption of hydrocarbon contaminants. The phenomenon of self-regeneration of highly hydrophobic properties is observed after the removal of organic impurities from the surface using different methods. The possibility for the cyclic switching of wettability from superhydrophobicity to hydrophilicity and back is demonstrated by successive coating treatment in plasma at a variation of its composition from atomic hydrogen plasma to methane plasma.

Transport of exhausted thermonuclear fuel in the ITER divertor and pumping duct was modeled on a specially designed dc glow discharge setup using mass spectrometry, optical and electron microscopy, and electron probe microanalysis. Transport and deposition of hydrocarbon radicals transferred in an H2/C x H yx mixture through a hollow stainless steel anode at a total mixture pressure of 8–212 Pa and a methane content to 15 mol % were considered. It was shown that deposition of radicals and ions (CH3, C2H3, C2H5) with kinetic energies of 0.03–3 eV on the anode inner surface at 600 K was suppressed to a large extent. In the temperature range of 600–800 K, deposition of ions and radicals with kinetic energy of ~3 eV was partially restored with the formation of soft a-C:H films, while thermalized radicals were not condensed.

Selective oxidation of amorphous hydrocarbon (a-C:H) films deposited on tungsten, molybdenum, and stainless steel by chemically active oxygen (with a source of glow discharge in air) has been studied. Film oxidation was carried out both directly in the discharge and in the area of afterglow. It has been shown that plasmolysis products of a-C:H films in air are CO, CO2, H2O, and H2. The rate of film oxidation depended on the position in relation to plasma and decreased in the hollow cathode-positive column-afterglow series. The coefficients of carbon erosion in afterglow increased from 10−3 to 10−2 at. C/at. O at a temperature increase from room temperature to 130°C.

The stream technique was used to comparatively analyze the characteristics of the deposition of a-C:H films from methyl radicals transferred by a carrier gas CH 4 /C 2 H y /H 2 ( y = 2, 4, 6) in a quartz tube with cylindrical insets made of Cu, Ni, Fe, W, Si, and stainless steel (SS), initial and coated with thin Pd or Rh films, over the temperature range 300–1000 K. The deposition of methyl was fully suppressed in a tube section heated to 380–800 K with all the insets specified. During further mixture movement outside this section in the tube with a decreasing wall temperature, carbon deposition resumed. The most effective catalyst of the hydrogenation reaction was stainless steel. Radicals and unsaturated hydrocarbons capable of polymerization at 300–400 K were fully removed from the carrier gas flow (CH 4 /C 2 H y /H 2 ) after several hundreds of collisions with the surface of SS heated to 420–470 K. The possibility of creating an SS recombination filter for hydrocarbon radicals (the performance of radical hydrogenation reactions) transferred by a CH 4 /C 2 H y /H 2 laminar flow was demonstrated. The deposition of a thin Pd film (∼10 nm) on steel did not increase the effectiveness of the surface with respect to radical recombination reactions. At the same time, Rh films increased the catalytic effectiveness of the surface of SS with respect to the hydrogenation of methyl and unsaturated hydrocarbons (380–420 K). The data obtained were used to select temperature conditions and mutual arrangement for the construction elements of an ITER diverter made of tungsten and stainless steel.

Transfer and deposition of the decomposition products of a dc glow discharge with hollow cathode in a hydrogen/methane flow are discussed. Hydrocarbon (a-C:H) films were deposited at inner surfaces of the hollow cathode and quartz tube bounded the discharge. The carbon deposition rate in the hollow cathode was 3–10 times higher than in the positive column and in afterglow range. Acetylene, ethylene, and ethane prevailed in the plasma-reaction gaseous products. When molecular nitrogen was introduced to the near-cathode plasma at a flow rate equal to or higher than that of methane, the carbon deposition rate at the cathode inner surfaces dropped down by 1.5 to 2 orders of magnitude. The carbon that has been consumed in the a-C:H films formation in the cathode is now transformed mainly to hydrogen cyanide (HCN). The carbon deposition rate in the positive column and in afterglow range ( T = 300 K) were comparable with those in the H 2 /CH 4 mixture. In the a-C/N:H deposits, the nitrogen concentration was 15 to 25 at %. The experiments showed that nitrogen can be used as a component of the gas flow specially introduced near the mirror in protecting the optical surfaces in diagnostic channels of the ITER tokamak against a-C:H film deposition.