2015_Взаимодействие ионов с поверхностью (ВИП)
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- ПубликацияОткрытый доступABLATION OF HIGH-Z MATERIAL DUST GRAINS IN EDGE PLASMAS(НИЯУ МИФИ, 2015) Marenkov, E.; Krasheninnikov, S.; Маренков, Евгений ДмитриевичNowadays it is well recognized that dust particles can play an important role in fusion plasma performance and material transport [1]. Therefore, it is important to have a good understanding of the most important processes dust grains encounter in the course of the interactions with fusion grade plasmas. Many fundamentals of grain-plasma interactions were developed by dusty-plasma community. However, grain-plasma interactions in fusion devices have some important distinctions. In particular, in hot and dense fusion plasma environment dust grains ablate rather quickly. The effect of the vapor on grain-plasma interactions can only be neglected for relatively small grains (below ~10 microns). Meanwhile, it is important to know how the vapor “shielding” alters grain-plasma interactions for larger (~100 microns) grains, which may pose significant threat for plasma performance and even result in disruption, especially for the case where these are high-Z material grains.
- ПубликацияОткрытый доступANALYSIS OF ION FLUXES IN LINEAR PLASMA DEVICES(НИЯУ МИФИ, 2015) Sorokin, I. A.; Vizgalov, I. V.; Bidlevich, O. A.; Сорокин, Иван АлександровичAnalysis of both ion mass-spectrum and plasma parameters is very important for plasma-surface interaction experiments to control discharge regime and ion composition. In linear plasma devices with a magnetic field, it is possible to apply a static mass-spectrometer using magnetic field of plasma device to ion separation with focusing at 180 or 360 degree.
- ПубликацияОткрытый доступCHARACTERISATION OF PLASMA PARAMETERS OF INDUCTIVELY - COUPLED PLASMA SOURCE AND ITS APPLICATION FOR NITRIDING OF STEELS(НИЯУ МИФИ, 2015) Meshcheryakova, E.; Zibrov, M.; Kaziev, A.; Khodachenko, G.; Pisarev, A.; Казиев, Андрей Викторович; Писарев, Александр АлександровичInductively coupled plasma (ICP) sources are widely used in many technological applications, including etching of semiconductors, thin film deposition, and surface modification of materials [1]. In particular, ICP plasmas could be attractive for plasma nitriding of metals (steels, titanium, aluminium, etc.) due to the following features: high ionization degree (up to several percent), low pressure (down to 10−4 mbar) that results in increase of energy of ions bombarding a substrate and reduction of their energy spread, and relatively small impurity content in the plasma due to electrodeless nature of the discharge. Consequently, thorough characterization of plasma parameters in ICP sources is essential for revealing the optimal regimes of plasma nitriding.
- ПубликацияОткрытый доступCOMPARISON OF EROSION AND DEPOSITION IN JET DURING CARBON AND ITER-LIKE CAMPAIGNS(НИЯУ МИФИ, 2015) Krat, S.; Gasparyan, Yu.; Pisarev, A.; Mayer, M.; de Saint-Aubin, G.; Bykov, I.; Coad, P.; Likonen, J.; van Renterghem, W.; Ruset, C.; Widdowson, A.; JET-EFDA, contributors; Гаспарян, Юрий Микаэлович; Крат, Степан Андреевич; Писарев, Александр АлександровичErosion of plasma facing elements in fusion devices is an important question affecting their lifetimes. Redeposition of eroded materials may lead to accumulation of hydrogen isotopes, which makes it an important problem from the perspective of radiological safety. Redeposition in layers with carbon and beryllium could be a channel for hydrogen isotope accumulation.
- ПубликацияОткрытый доступDETERMINATION OF HYDROGEN BINDING ENERGIES WITH DEFECTS IN METALS FROM THERMAL DESORPTION MEASUREMENTS WITH DIFFERENT HEATING RATES(НИЯУ МИФИ, 2015) Zibrov, M.; Gasparyan, Yu.; Shubina, A.; Pisarev, A.; Писарев, Александр Александрович; Гаспарян, Юрий МикаэловичInvestigation of hydrogen isotope behaviour in plasma-facing and structural components is of great importance for successful development of fusion reactors with magnetic confinement. The hydrogen inventory (especially in the metals with a positive heat of solution) is determined by the presence of defects, which act as trapping sites for hydrogen. Therefore precise determination of defects’ parameters, namely binding energies for hydrogen atoms and their concentration is essential. Thermal desorption spectroscopy (TDS) is a commonly used method for such purposes. The trap parameters are usually determined by fitting of simulated TDS spectra to experimental ones using numerical diffusion-trapping codes, such as TMAP7 [1]. In such approach, the determination of the characteristics of the trapping sites is ambiguous – they act as free parameters in the model and, as a result, one spectrum can be fitted by using several combinations of parameters.
- ПубликацияОткрытый доступERO-PSI CODE FOR NUMERICAL SIMULATION OF EXPERIMENTS ON TUNGSTEN SPUTTERING IN LINEAR PLASMA DEVICE PSI-2(НИЯУ МИФИ, 2015) Eksaeva, A. A.; Marenkov, E. D.; Borodin, D.; Kirshner, A.; Laenger, M.; Kurnaev, V. A.; Kreter, A.; Маренков, Евгений ДмитриевичPlasma-wall interaction is one of the recognized issues for thermonuclear reactor performance and seems to be a key direction in fusion researches in the framework of the ITER project [1]. Tungsten (W) has been chosen as a main material for construction of ITER divertor due to its low sputtering at edge plasma temperatures, large melting temperature, and small uptake of tritium.
- ПубликацияОткрытый доступFABRICATION OF FINE-DISPERSED COATINGS AT DEPOSITION WITH SIMULTANEOUS SPUTTERING(НИЯУ МИФИ, 2015) Rogov, A. V.; Martynenko, Yu. V.; Kapustin, Yu. V.; Belova, N. E.; Мартыненко, Юрий ВладимировичNew low temperature method of homogeneous Mo nanocrystallite coating formation was developed. The coating was formed at magnetron Mo deposition on polished Mo polycrystalline substrate with simultaneous ion sputtering. Deposition and sputtering were performed in combined discharge of magnetron – hole cathode [1]. X-ray difractometry and SEM were used for coating structure investigation. A theoretical model was developed for coating formation by proposed method. At low excess of deposition rate over sputtering rate uncontrolled fast growth of some Mocrystallites is effectively suppressed, being fine dispersed coating is formed. Such coatings can be used as a radiation stable reflecting coatings for high temperature plasma diagnostic mirrors [2, 3]. The proposed method can be used also for other materials modification, semiconductors included.
- ПубликацияОткрытый доступFUTURE DIRECTIONS IN EDGE PLASMA PHYSICS AND PLASMA MATERIAL INTERACTIONS IN FUSION DEVICES: SOME RESULTS FROM THE FES COMMUNITY PLANNING WORKSHOPS 2015(НИЯУ МИФИ, 2015) Krasheninnikov, S. I.In February 2015, Dr. Ed Synakowski, USDOE FES Associate Director, has announced a set of Community Planning Workshops that are intended to seek community engagement and input for future program planning activities (see the website https://www.burningplasma.org/activities/article=FES%20Community%20Planning%20Wor kshops%202015). Particular objectives of the workshops are: discussion of near- and longterm research tasks, such as experiments that could be performed on existing experimental facilities; possible upgrade of existing facilities and diagnostics capabilities that would enable of enhance the research tasks; identification of areas for which modeling and simulations could be impactful. In my talk I’ll present some results from two of these workshops, scheduled to take place in May-June 2015, which are aimed on the physics of edge plasma and plasma-material interactions in fusion devices.
- ПубликацияОткрытый доступINTERACTION OF LITHUM-DEUTERIUM FILMS WITH ATMOSPHERIC GASES(НИЯУ МИФИ, 2015) Popkov,A. S.; Krat, S. A.; Gasparyan, Yu. M.; Pisarev, A. A.; Гаспарян, Юрий Микаэлович; Писарев, Александр Александрович; Крат, Степан АндреевичA choice of plasma-facing materials is one of the key issues in thermonuclear fusion reactor design. Lithium as an element with the low atomic number is a promising material for plasma-facing components (PFC) in fusion installations and a number of experiments at tokamaks already demonstrated many positive effects on plasma operation [1,2]. Lithium can be used for conditioning, PFC on the base of of capillary porous system with liquid lithium are also considered. In any way, one can expect lithium co-deposition with hydrogen isotopes at the surface of PFC and at remote areas. Lithium as a good getter can accumulate high amount of hydrogen isotopes (deuterium, tritium) that can be a problem from the safety reason. Deuterium retention and thermal desorption from lithium films formed in plasma discharge were investigated in this work.
- ПубликацияОткрытый доступMetal-ion Penning source for thin films deposition(НИЯУ МИФИ, 2015) Колодко, Д. В.; Синельников, Д. Н.; Казиев, А. В.; Тумаркин, А. В.; Тумаркин, Александр Владимирович; Колодко, Добрыня Вячеславич; Казиев, Андрей Викторович; Синельников, Дмитрий НиколаевичRecently, research areas dealing with coating processes in a magnetron discharge with melted cathode have experienced intensive development [1–3]. In this mode magnetron discharge is operated in the target's vapour and the plasma in this case is purely metallic. Despite the main contribution to the deposition process is introduced by the vaporized (neutral) component, the coating properties are greatly affected by the ion flux [3]. So, it is important to study the process of deposition by ion flux solely.
- ПубликацияОткрытый доступMigration, trapping and release of deuterium from tungsten in the presence of high density of defects: theory and experiment(НИЯУ МИФИ, 2015) Ogorodnikova, O. V.; Огородникова, Ольга ВячеславовнаThe most common experimental methods to study hydrogen (H) in a metal are nuclear reaction method (NRA) for depth profile measurements, thermal desorption spectroscopy (TDS) and permeation experiments. Rate equations are used to model experimental data. The diffusivity, solubility, reflection coefficient, surface barrier, binding energies of H with different types of defects and density of defects are input parameters for rate equation model. These parameters can be derived from the first-principle (DFT) calculations, effectivemedium theory (EMT), molecular dynamics (MD) and TRIM calculations. Incorporation of binding energies of deuterium (D) with a vacancy and a dislocation recently calculated by DFT [1,2] and penetration probability and ion range calculated by MD and TRIM [3] in the rate equation model allows us to validate different predictions against experimental data, for the first time. A comparison of the first-principle calculations and calculations by other theoretical models with experimental values can clarify the physics underling the hydrogenmetal interaction and can provide an answer on several important questions, namely, (i) which type of trap corresponds to certain D binding energy, (ii) which is a range of validity of MD and TRIM models and (iii) which process is rate-limited in respect to the D uptake and release in a material.
- ПубликацияОткрытый доступPLASMA NITRIDING OF TITANIUM ALLOY TI5A14V2MO(НИЯУ МИФИ, 2015) Borisyuk, Yu. V.; Berdnikova, M. A.; Tumarkin, A. V.; Khodachenko, G. V.; Pisarev, A. A.; Oreshnikova N. M.; Писарев, Александр Александрович; Тумаркин, Александр ВладимировичHowever, low hardness and low wear resistance of these materials is one of the reasons limiting their wider use. Nitriding of titanium alloys with the purpose of improvement of their wear resistance is an important task. Many works were devoted to nitriding of titanium and low alloyed titanium [1-4], but not much is known about nitriding of highly alloyed titanium, which is a promising material for many applications The superalloy Ti5Al4V2Mo has high strength and corrosion resistance, and it is widely used in industry at medium and high temperatures. Nevertheless, it was not studied in terms of plasma nitriding. This work is devoted to investigation of nitriding of Ti5Al4V2Mo in argon-nitrogen plasma of abnormal glow discharge.
- ПубликацияОткрытый доступPROPERTIES OF POLARIZATION RADIATION FROM CHARGED PARTICLES BEAM BRUSHING SURFACE OF A SOLID(НИЯУ МИФИ, 2015) Tishchenko, A. A.; Sergeeva, D. Yu.; Strikhanov, M. N.; Стриханов, Михаил Николаевич; Тищенко, Алексей Александрович; Сергеева, Дарья ЮрьевнаTransition radiation (TR) and Diffraction radiation (DR) can be interpreted as a result of action of a charged particle upon a target. These types of radiation have similar nature and arise due to the dynamic polarization of the target material by the Coulomb field of the charged particles. TR is generated when the beam crosses the media surface; DR is generated when the beam moves above the inhomogeneous medium, e.g. above the side of a slab.
- ПубликацияОткрытый доступSTUDY OF PLASMA INTERACTION WITH FUSION REACTOR MATERIALS AT THE LINEAR SIMULATOR WITH A BEAM-PLASMA DISCHARGE(НИЯУ МИФИ, 2015) Gutorov, K.; Vizgalov, I.; Podolyako, F.; Sorokin, I.; Подоляко, Федор Сергеевич; Сорокин, Иван Александрович; Гуторов, Константин МихайловичLinear simulators with electron beam driven generation of plasma have some advantages for plasma-surface interaction investigations. Key features of such installations are considered on the example of the PR-2 simulator [1] in Moscow. This plasma beam machine with a longitudinal magnetic field and the electron beam generated plasma has a total power of 50 kW in a steady state regime, which allows target loading with several megawatts per square meter and intensive hydrogen ion fluxes (1022 m-2s-1). A set of diagnostic systems of the installation allows characterizing in details the processes in plasma: Langmuir and magnetic probes, ion composition and energy analysis, plasma emission spectrometry, gas composition spectrometry, IR camera. The PR-2 setup is presented in figure 1.
- ПубликацияОткрытый доступTECHNOLOGICAL APPLICATIONS OF PLASMA SURFACE INTERACTIONS(НИЯУ МИФИ, 2015) Pisarev, A.; Писарев, Александр АлександровичPlasma is the forth state of matter, which is characterized by a high intrinsic temperature. Interaction of this substance with matter leads to serious consequences both for the matter and the plasma. Many effects of plasma-surface interactions are used for practical purposes, and this brief review gives some examples. We will concentrate on applications of low temperature plasma, which is characterized by the electron temperature below 105 K.
- ПубликацияОткрытый доступTungsten nano-fuzz surface degradation under ion beam(НИЯУ МИФИ, 2015) Sinelnikov, D.; Kurnaev, V.; Kolodko, D.; Solovev, N.; Колодко, Добрыня Вячеславич; Синельников, Дмитрий НиколаевичTungsten is the main candidate for plasma facing material in the divertor zone of a thermonuclear reactor due to high melting temperature, high thermal conductivity and low sputtering erosion yield. However, its surface can be modified by "fuzz" nanostructure, which can form in linear simulators and tokamaks [1] under helium irradiation fluence as high as ~1025m-2and sample temperature in the range of 1000-2000 K. Such structure significantly changes the plasma-wall interaction balance, which results in higher probability of unipolar arc ignition. In the case of arcing, erosion yield sharply increases, especially if arcing takes place on a fuzzy surface [2]. Tungsten fuzz is also characterized by high pre-breakdown current intensity, which could indicate the initial stage of unipolar arc ignition [3]. Prebreakdown currents are usually initiated by field emission due to amplification of electric field on sharp cathode relief. So, an investigation of emission properties dependence on surface relief during fuzz formation and destruction seems to be important for the prediction of unipolar arcing.
- ПубликацияОткрытый доступVAPOUR SHIELDING OF SOLID TARGETS EXPOSED TO HIGH HEAT FLUX(НИЯУ МИФИ, 2015) Pshenov, A. A.; Eksaeva, A. A.; Krasheninnikov, S. I.; Marenkov, E. D.; Маренков, Евгений ДмитриевичThe thickness of a Tungsten monoblocks composing future ITER divertor is supposed to be 8 mm only. Severe erosion caused by a high heat fluxes during transients, such as Type I ELMs and disruptions, therefore is a limiting factor to PFCs lifespan. Thermal loads over the range of Q = 0.5−2 MJ/m2 on the timescale of τ = 0.3− 0.6 ms are expected during Type I ELMs. Even larger heat fluxes, of the order of = − Q 0.5 5 MJ/m2 are expected during thermal quench stage of disruption lasting approximately τ = 1 −3 ms [1]. Under the influence of the extreme heat fluxes serious surface modification and cracking of the Tungsten monoblocks is anticipated [2]. Moreover, melting of a thin surface layer is likely. Melt motion contributes seriously to the material erosion [3]. The other sources of erosion are melt splashing, in form of a droplet ejection, and stationary evaporation [4]. These mechanics lead to a cold dense secondary plasma region formation near the irradiated surface. Intense re-radiation of the incident plasma flow energy in the secondary plasma layer results in a significant reduction of the heat flux reaching the target surface [5]. Accounting for this vapour shielding effect is essential to estimate the surface erosion properly. Predicting the divertor plates lifespan therefore requires deep understanding of all the processes mentioned and their interplay.