Andrey Markin

Andrey Markin
Frumkin Institute of Physical Chemistry and Electrochemistry | IPCE RAS

Diplom of Specialist

Publications

Publications (64)
Article
Full-text available
Studies of contaminants obtained by spraying ITER-grade Be on a quasi-stationary plasma gun facility QSPA-Be are presented. Contaminating films, consisting mainly of Be and O in approximately equal proportions, were deposited on substrates of quartz, sapphire, single crystalline silicon (SC-Si) and NaCl crystal. Characterization of the deposits was...
Article
Full-text available
Leucosapphire (c-LS) structure and transmission in visible after surface treatment in 90%H 2 -10%N 2 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-...
Article
The effect of D2–N2 glow discharge plasma on the reflectivity of single-crystal Mo(111) mirrors is studied. The surface of each mirror is processed by mechanical polishing with diamond pastes to a roughness of hq = 5 nm. During polishing, abrasive particles are embedded in the surface layer of the mirror. Exposure to an ion fluence of 1.4 × 10²⁴ m–...
Article
The evolution of indestructible blistering in molybdenum foils with the Mo {100} texture is investigated in dc glow discharge in a D2–N2 mixture with a nitrogen molar fraction in the mixture varying from zero to unity at 100 V potential negative with respect to plasma, a total pressure of 15 Pa, and temperatures of 30–60°C. After the addition of 0....
Article
Full-text available
The development of the first mirror cleaning and recovery system is one of the challenges for all optical diagnostics in ITER. This study is focused on capacitively coupled radio frequency (CCRF) discharge as a promising method for removal of metal deposits. The physical aspects of the RF discharge application are discussed with a focus on implemen...
Article
A technique for tungsten-film deposition on different substrates in asymmetrical high-frequency (1.76 MHz) capacitive discharge in a D2−6.5 mol % O2 mixture under a total pressure of 15 Pa and at 60–130°C is considered. A circular W strip near the upper inner edge of a cylindrical hollow cathode with a radius of 4.2 cm and a height of 10 cm is the...
Article
Full-text available
Sputtering of Mo and Al (as Be proxy) in mixed D2/N2 DC glow discharge was studied in view of the first mirror performance. The composition of the working gas was varied from 100% D2 to 100% N2, while keeping a total pressure of 15Pa. The ion energies striking the sample surface were defined by its 100V biasing negative to a floating potential. It...
Article
Recent data on the blistering process in polished polycrystalline Mo for the case of direct-current glow discharge in deuterium and D2/2–4 mol % O2 or N2 admixtures, at an energy of incident molecular ions of 70–120 eV and a pressure of 14 Pa, are reported. Depending on the method of metal surface polishing, the initial metal grains are broken up i...
Article
Tritium retention inside the vacuum vessel is a potentially serious constraint in the operation of large-scale fusion machines like ITER. An in situ diagnostics for first wall H/D/T retention by laser induced desorption spectroscopy (LIDS) is proposed for use between plasma discharges. The technique is based on local baking of the first wall by las...
Article
Full-text available
Almost all optical diagnostic systems in ITER will require the implementation of mirror recovery and protection systems. Plasma cleaning is considered to be the most promising technique for the removal of metal deposits from optical surfaces. The engineering and physical aspects of RF discharge application for continuous or periodic plasma treatmen...
Article
The peculiarities inherent to a-C:H film removal, Mo oxidation in a flowing glow discharge of oxygen, and molybdenum-oxide reduction in deuterium discharge are investigated at T = 300–320 K. After carbon is removed under O2 discharge conditions, a steady-state MoO3 layer with a limiting thickness of 25–30 nm is formed on large-block molybdenum with...
Article
An interaction of deuterium plasma with seeding species with a material is, in particular, an issue for medium- and high-Z plasma-facing materials for fusion devices to reduce the power load in front of material surfaces. In this paper, we investigated the influence of seeding of nitrogen (N) into deuterium plasma on the accumulation of deuterium (...
Article
Methods for measuring the layer-by-layer profiles of hydrogen in structural materials based on interpretation of the energy spectra of electrons reflected within a given spatial angle are discussed. Elastically reflected spectroscopy makes it possible to determine the hydrogen isotope content, but its implementation requires an energy resolution on...
Article
Mass spectrometry and CH emission spectroscopy are applied for the evaluation of the erosion yield under conditions when the eroded hydrocarbons undergo several cycles of sticking and erosion before leaving the target chamber. Two differentially pumped quadrupole mass spectrometers (QMS) installed at the target chamber and at the pump duct show qua...
Article
The influence of nitrogen injection on the formation of a-C:H films in areas far away from the plasma as well as close to the plasma boundary was studied in the PSI-2 device for collector temperatures between 310 and 350K. The balance between deposition and erosion determines the net growth rate. Small amounts of nitrogen (Φ(N2)≈Φ(CH4)≈2% Φ(H2)) st...
Article
The deposition of amorphous hydrocarbon (a-C:H) films and the influence of nitrogen on these films were studied. The experiments were performed in low temperature plasmas with Te = 3...6 eV and ne = 1.1016...4.1017 m-3. The ratio between injected nitrogen and methane was varied as well as the substrate temperature and the neutral gas pressure. Addi...
Article
Hydrocarbons were injected into the plasma generator PSI II to study the formation of deposition layers. The experimental results are compared with those obtained from ERO-code modeling. Using available data of rate and sticking coefficients in the simulations the agreement is not satisfying. New experimental results point to a hydrocarbon decompos...
Article
The stationary plasma of the plasma generator PSI 2 is used to study the gas balance of hydrocarbons and hydro‐gen by means of mass spectrometers. For this purpose H2, acetylene and ethylene are injected into argon and hydrogen plasmas.. It is found that hydrogenation of the hydrocarbon layers is strongly influenced by the hydrocarbon species injec...
Article
The results of the experiments with QMS and IR-TDLAS are in good agreement for stable molecules. The densities of the hydrocarbon radicals were below the detection limit of IR-TDLAS but an upper limit for the densities could be obtained from the measurements. It is found that the decomposition process in hydrogen plasmas is more pronounced than in...
Article
The transport and deposition of hydrocarbons were studied in the stationary plasma of plasma generator PSI-2. CH4 or C2H4 were injected into the plasma at different positions in the target chamber. After an interaction between the plasma and the hydrocarbons, different species are produced, some of them having high sticking probabilities and formin...
Article
A series of experiments dedicated to the analysis of transport and sticking of hydrocarbon molecules have been performed in the plasma generator PSI-2. As a source of hydrocarbons defined amounts of CH4 and C2H4 have been injected. After injection the molecules undergo a series of ionisation and dissociation reactions. The thickness change of depos...
Article
The surface loss probability, β, of methyl (CH3) radicals and atomic (H) hydrogen on a growing film surface was measured at lowered temperatures. The loss of reactive species was investigated by analysis of the deposition profiles along a quartz tube reactor directly coupled with a methane RF discharge (so-called ‘stream’ technique). The experiment...
Article
Data on deuterium retention in W single and polycrystals exposed to D plasma at 500 K are presented. The energy of D ions was well below the threshold of damage production. In a W polycrystal the deuterium spreads to a depth of about 4 μm. In contrast, no deuterium was found even at a depth of 2 μm in a W single crystal. This is an indication of si...
Article
The surface loss probability β of CH3 radicals at a-C:H surfaces has been determined by analysis of the carbon deposition profiles along a tube flow reactor directly coupled with a methane RF discharge. β is equal to (1.0±0.2)×10−3 for a methyl to atomic hydrogen flux ratio of 10:1. β remains the same in the temperature range 300–800 K and decrease...
Article
Deuterium-loaded BeO films were produced by sputtering the beryllium target with 10 keV Ne ions in D2 gas at a pressure of approximately 1 Pa. The sputtered beryllium reacts – on the substrate surface – with the residual oxygen, thus forming a beryllium oxide layer. Biasing the substrate negatively with respect to the target provides the simultaneo...
Article
The increased safety concern, resulting from the accumulation of tritium in the redeposited carbon-dominated films forming on the surfaces of the ITER divertor private region plasma facing components, has stimulated an important change of the gas box liner design. A significant modification of the ITER divertor cassette design was undertaken in the...
Conference Paper
Deuterium trapping in beryllium oxide films irradiated with 400 eV D ions has been studied by Thermal Desorption Spectroscopy (TDS). It has been found that for thermally grown BeO films implanted in the range 300-900 K the total deuterium retention doesn't depend on irradiation temperature whereas TDS spectra are temperature dependent. For R.T. imp...
Article
Deuterium trapping in beryllium oxide films irradiated with 400 eV D ions has been studied by Thermal Desorption Spectroscopy (TDS). It has been found that for thermally grown BeO films implanted in the range 300–900 K the total deuterium retention doesn’t depend on irradiation temperature whereas TDS spectra are temperature dependent. For R.T. imp...
Article
The structure and the electronic transport in pure tungsten single crystals, irradiated by deuterium ions (E=70 eV, fluence 10^19 ions/cm^2), were studied by the reflected high energy electron diffraction (RHEED) method and by magnetoresistivity. It was observed that the new phase, based on the deuterium and tungsten atoms, is formed near sample su...
Article
Thermal desorption of deuterium from TIP-30 beryllium irradiated with 5 keV D ions to fluences Φ from 1019 to 1022 D/m2 has been studied by means of Thermal Desorption Spectroscopy. At Φ<1×1021 D/m2 a deuterium release in the form of D2 and HD molecules is described by the liberation of D atoms bound at vacancy complexes, followed by atom diffusion...
Article
The experiments on large tokamaks on measuring the hydrogen isotope pressure in the near-wall or divertor plasma are briefly described. Based on the analysis of exchange fluxes between the plasma and the wall it is stated that the plasma action, with respect to hydrogen sorption by graphite components of the tokamak first wall, is identical to mate...
Article
By means of thermal desorption spectroscopy (TDS), effect of air oxidation on deuterium release from carbon fiber composite SEP N112-A and fine grain graphite POCO AXF-5Q has been studied. Carbon samples were loaded with deuterium by exposure to 133 Pa D2 at 1170 K for 2 h. Thermal desorption from SEP proceeds over a wide range, 1200 to 1900 K, wit...
Article
Conclusions The conditions have been proposed for performing modeling experiments making it possible to predict the accumulation of hydrogen isotopes in carbon materials which are in contact with a tokamak plasma acting as a source of particles having a flux density of between 3×1016 and 3×1019 cm−2·sec−1. By analyzing the reemission fluxes formed...
Article
The aims of the paper are the following: 1) to propose a technique for experiments intending for forecasting the limiting concentration of hydrogen isotopes in graphite elements of the linear structure by means of comparatively simple tests with molecular hydrogen without plasma experiments at tokamaks; 2) for given intervals of hydrogen pressure a...
Article
The current status of research in the area of hydrogen retention and release for the prime candidate plasma-facing materials is briefly reviewed. Physical understanding of the basic problems of hydrogen behavior in the surface layers and material bulk of graphite, beryllium and tungsten is emphasized. The data base in the field obtained in laborato...
Article
An extensive TEM study of the microstructure of Be TIP-30 irradiated with 3 and 10 keV D ions up to fluences, Φ, in the range from 3 × 1020 to 8 × 1021 D/m2 at temperatures, Tirr = 300, 500 and 700 K has been carried out. Depth distributions of deuterium in a form of separate D atoms and D2 molecules have been investigated by means of SIMS (seconda...
Article
The experimental data on adsorption and solubility of hydrogen isotopes in graphite over a wide range of temperatures and pressures are reviewed. Langmuir adsorption isotherms are proposed for the hydrogen—graphite interaction. The entropy and enthalpy of adsorption are estimated, allowing for effects of relaxation of dangling sp2 bonds. Three kind...
Article
The interaction of deuterium atoms with type TIP-30 beryllium has been studied. A plasma source with a heated cathode was used to produce deuterium atoms. The sample was under positive potential of +80 V to repulse the deuterium ions. The atomic flux was estimated at 1016 cm−2 s−1. After exposures to different doses at 740 K, the deuterium distribu...
Article
By means of TDS measurements it is shown that the desorption of deuterium from Be implanted with 5 keV D-ions to fluences, Φ, from 1 × 1020 D/m2 to 1 × 1021 D/m2 proceeds in one high-temperature stage B, while at Φ ≥ 1.2 × 1021 D/m2 one more stage A appears. The desorption maximum A is narrow and consists of two peaks A1 and A2 at about 460 K and 4...
Article
Full-text available
An extensive TEM study of the microstructure of TIP-30 Be implanted with 3 and 10 keV D ions to fluences, Φ in the range from 3 × 1020 to 8 × 1021D/m2 at temperatures, Tirr = 300, 500 and 700 K has been carried out. Depth distributions of separate D atoms and D2 molecules have been investigated by means of SIMS and RGA methods, correspondingly. D i...
Chapter
The great attention attracted at present to the problem of hydrogenation of a diamond is caused by the fact that CVD diamond grows from the gas phase containing more than 90% of hydrogen, which is able to penetrate into the structure of growing film. In opinion of a number of authors [1,2,3,4] hydrogen influences upon conductivity of CVD diamond fi...
Chapter
Description Comprehensive look at the latest research on how radiation effects metal and non-metal materials, with emphasis on fundamental mechanisms of damage and applications to nuclear systems. Over 80 peer-review papers in 15 sections. The diversity of the selections cover a complete range of topics, including: • The importance of research on r...
Article
Results of studying radiation erosion of structural materials of nuclear reactor first wall caused by consecutive multiple effect of pulse processes, imitating plasms quenching, and helium ion fluxes with energy of 40 keV and fluence 2×1021, 1×1022 m-2 are presented. High-temperature plasma fluxes with power density of the falling flux equalling up...
Article
Damage structure in austenitic stainless steels irradiated by 40-keV helium ions under stress at isothermal and thermocyclic conditions as well as those resulting from post-irradiation high temperature deformation have been studied using the techniques of transmission electron microscopy, scanning electron microscopy and the method of thermodesorpt...
Article
Large and inhomogeneous stresses are associated with irradiation swelling in the first wall of a fusion reactor or in a fuel-pin sheath or fuel-assembly component because there is a superposition of stresses together with stationary and nonstationary temperature gradients. In this paper, scanning and transmission electron microscopy and gas-release...
Article
The authors develop a method of recording the desorption of helium during a high-temperature deformation. The method was tested with Kh20N45 alloy samples which had been previously irradiated with 40-keV helium ions. The desorption rate decreased uniformly during a 2-h exposure at 1000 degrees K. The dependence which the authors obtained for the ra...
Article
Full-text available
The paper reports the progress made by the ITER Home Teams in the development of robust carbon and tungsten armoured plasma facing components for the ITER divertor. The activities on the development and study of armour materials, joining technologies, non-destructive evaluation techniques, high heat flux testing of manufactured components and neutr...

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