The choice of plasma contact materials and configurations for power fusion reactors is still not obvious. The tokamak with reactor technologies (TRT) under construction should help resolve this ...issue. Therefore, the most complete study of the effect of plasma on the tokamak divertor for various types of discharges and an analysis of their consequences are of great importance. Divertor probes are devices that measure thermal and corpuscular flows toward the surface of a divertor and/or record the results of their impact on the divertor. They have found wide application in fusion facilities. The features, advantages, and disadvantages of the divertor probes presented in literature, as well as cases of using samples of materials or devices to solve individual problems to which divertor probes are applicable are discussed in this work. A preliminary design and thermal calculations of the divertor probe for the TRT tokamak are presented, which, according to the authors, is capable of performing a set of measurements that make it possible to draw a conclusion about the mechanisms and regularities of processes on the divertor surface depending on the parameters and conditions of plasma irradiation, as well as to speed up the determination of optimal materials and modes of plasma irradiation of divertor tiles.
It was shown (Buzhinsky, 2003) that in situ renewable coating of boron carbide can protect the tiles of the divertors of thermonuclear facilities from destruction and also to prevent accumulation of ...remarkable amounts of tritium in the plasma facing materials. In the paper presented a plasma method for deposition of boron carbide coating with a high adhesion to tungsten was developed. In the laboratory installation boron carbide coating on tungsten was subjected to cycling irradiation by the deuterium ion flux with power density up to 5.0 MW/m2 in the temperature range up to 1500 K. The results of the tests showed that the composition, integrity and adhesion of the coating were not violated in the laboratory tests. In the T-10 tokamak the behavior of the coating was investigated in the temperature range up to 3600 K when irradiated with plasma power in the range of 20-100 MW/m2 during plasma disruption. Being irradiated in T-10 tokamak, the coating retained its continuity, adhesion and protected tungsten from the effect of the even at temperatures of 2500-3600 K, when the coating melted under irradiation and its composition changed to B:C ≈ 1:1.
The results from experiments on measuring the rate of gasification for carbon and boron–carbon films and carbon fiber composite (CFC) exposed in oxygen–ozone mixtures are presented. The rate of ...gasification is 0.4–0.6 μm h
–1
(at temperatures of 220–250°C, a pressure of 0.3 atm, and an ozone concentration of 0.6 at %) for carbon films; plane CFC samples; gaps 1 and 2 mm wide with walls of stainless steel; and gaps 1 mm wide with walls of CFC. It is 15 μm h
–1
for plane CFC at a temperature of 250°C, a pressure of 1 atm, and an ozone concentration of 10 at %. The rate of gasification for boron–carbon films is from 3 to 30 nm h
–1
for B/C ratios of 2.1 to 0.8 (at 250°C, 1 atm, and ozone concentration of 10 at %).
Tungsten layers with iron impurity were deposited on tungsten substrates modeling re-deposited layers in a fusion device. The samples were tested by thermocycling and hydrogen ion beam tests. ...Thermocycling revealed globule formation on the surface. The size of the globules depended on iron impurity content in the coating deposited. Pore formation was observed which in some cases lead to exfoliation of the coatings. Hydrogen ion irradiation lead to formation of blisters on the coating and finally its exfoliation.
The results of tests of plasma treatment of zirconium and deposition of protective yttrium coatings used as the methods of protection of zirconium components of light water reactor cores against ...hydrogenation are detailed. The amount of hydrogen in the treated sample exposed to superheated steam for 2500 h at temperature
T
= 400°C and pressure
p
= 1 atm was five times lower than the corresponding value for the untreated one. The amount of hydrogen in the sample coated with yttrium remained almost unchanged in 4000 h of exposure. A plasma method for rapid testing for hydrogen resistance is proposed. The hydrogenation rate provided by this method is 700 times higher than that in tests with superheated steam. The results of preliminary experiments confirm the possibility of constructing a unit for batch processing of the surfaces of fuel rod claddings.
The paper presents a short revue of the study of not been investigated specific features of hydrogen trapping in graphite occurring as the results of inelastic interaction of impinging ions with ...carbon materials (potential trapping). The influence of potential mechanism on different regularities of hydrogen trapping are considered. Among them there is trapping dependence on irradiating ion current density, ion energy, irradiation fluence, temperature of the investigated samples and oxygen addition in the plasma.
The paper presents the results of investigation of gas exchange through stainless steel surface of the plasma chamber under irradiation with hydrogen atoms in oxygen atmosphere or oxygen contaminated ...hydrogen plasma. Dependence of this process on various irradiation parameters, such as the metal temperature, energy of irradiating ions, gas composition of plasma are studied. It is shown, that desorption from stainless steel is activated with the increase of the plasma chamber walls temperature and energy of irradiating ions. Hydrogen release occurs also under irradiation of the walls by helium and argon plasmas added with oxygen, however the amount of released hydrogen is several times lower than in the case of irradiation with oxygen contaminated deuterium plasma.
In the paper, a simple and easy to operate stand is presented that allows irradiating the surface of solids by gas discharge plasma ions in the energies ranging from 5 to 40 keV. The results of first ...experiments are shown. Ion current parameters on the irradiated sample using gas discharge are presented for different gases.
A device intended for boron carbide coating deposition and material testing under high heat loads is presented. A boron carbide coating 5 μm thick was deposited on the tungsten substrate. These ...samples were subjected to thermocycling loads in the temperature range of 400–1500°C. Tungsten layers deposited on tungsten substrates were tested in similar conditions. Results of the surface analysis are presented.
Argon trapping in the depositing metal coating Begrambekov, L B; Grunin, A V; Sadovskiy, Ya A ...
Journal of physics. Conference series,
05/2017, Letnik:
830, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The paper has investigated conditions and parameters of argon trapping in molybdenum, tantalum and tungsten layers during their deposition on tungsten substrate by the atoms sputtered from the ...respective targets in argon plasma. The substrate temperature during deposition was 1273 K. The rate of deposition was 1 μm/h. It was shown that electron irradiation of the deposited layer with the beam intensity of 4 mA/cm2 initiated argon trapping in tungsten and tantalum coating with approx. 2 x 1027 at/m3 and 8 x 1026 at/cm3, respectively, but did not stimulate argon trapping in the molybdenum layers. Features of argon trapping in the tungsten coating and its release are investigated in detail.
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