Important progress in the development of high-temperature superconductors (HTSC) of the second group made it possible to design the quasi-stationary tokamak with reactor technologies (TRT) with the ...high magnetic field (
B
t0
= 8 T). The high magnetic field will ensure the achievement of plasma fusion regimes in the tokamak with the fusion energy gain
Q
> 1 at the considerably reduced size of the facility (
R
0
= 2.15 m,
a
= 0.57 m), and, consequently, at its reduced cost. TRT will be capable of operating in the quasi-stationary regimes (≥100 s) with hydrogen, helium, and deuterium plasmas (with the densities
n
e
of up to 2 × 10
20
m
–3
) and in the regimes with short (duration Δ
t
< 10 s) deuterium–tritium plasma shots with the fusion energy gain
Q
> 1 limited by the radiation heating of toroidal coils. TRT is being designed as a plasma prototype for both the pure fusion reactor and the fusion neutron source for the hybrid (fusion–fission) reactor. The TRT missions are the development of the key fusion technologies and their integration in one facility. These technologies are as follows: the HTSC electromagnetic system operating at the extremely high magnetic fields; the metal and liquid-metal (lithium) first wall and innovative divertor; the unique advanced systems for the auxiliary plasma heating and non-inductive current drive, including the systems for atomic beam injection with energy of 0.5 MeV and power of several tens of megawatts, the electron cyclotron heating system based on the megawatt-power gyrotrons with a frequency of 230 GHz and a total power of ~10 MW, and the ion cyclotron heating system at frequencies of 60–80 MHz with a power of several megawatts; the tritium fuel cycle; the remote control technologies; the technologies for diagnostics capable of operating under the fusion reactor conditions; the technologies for maintaining quasi-stationary plasma discharges; and the technologies for the tokamak operation in the fusion ignition regime, in which the heating by alpha particles is the dominant heating mechanism at the axis of the plasma column, in the deuterium–tritium experiments limited by the radiation heating of the toroidal coils. The results are presented from the conceptual design of the basic TRT components, as well as the expected characteristics of its operation. It is shown that TRT has a wide window of working parameters suitable for studying the reactor operating regimes. The high magnetic field provides the necessary margins of the pressure, MHD stability, and plasma controllability variation. Implementation of the advanced divertor and first wall concepts, including those using the liquid-metal technologies, will provide the optimum choice of design options in order to reliably control the heat and particle fluxes under the reactor conditions. The advanced systems for the auxiliary heating and current drive will make it possible to implement both the pulsed and stationary regimes of the reactor operation. Calculations of the TRT discharge scenarios show that, for the DT mixture with equal content of components, the long discharges (with duration exceeding 100 s) can be realized with a neutron flux of more than 0.5 MW/m
2
onto the wall, as well as the stationary discharges with a flux of approximately 0.2 MW/m
2
. Thus, TRT can be a real prototype of the fusion neutron source for the hybrid reactor.
The mode of continuous spinning detonation (CSD) combustion of hydrogen in the annular combustor of a model of a hydrogen-fueled detonation ramjet under conditions of approach air stream Mach number ...5.7 and stagnation temperature 1500 K is registered experimentally in a short-duration (pulsed) wind tunnel at the overall air-to-hydrogen equivalence ratio (ER) ranging from 0.7 to 1.4. The maximum values of thrust and specific impulse of the ramjet model are attained at ER = 1.25 and are estimated as 1550 N and 3300 s, respectively. At 1.4 < ER < 1.6, the mode of longitudinally pulsating detonation (LPD) combustion is registered with somewhat lower values of thrust and specific impulse.
•Hydrogen-fueled detonation ramjet is tested in wind tunnel at M5.7 and Tst = 1500 K.•1-m long 0.3-m i.d. ramjet comprises M5 air intake and expanding annular combustor.•Stable spinning detonation mode is obtained at fuel-to-air ratios from 0.7 to 1.4.•Stable pulsed detonation mode is obtained at fuel-to-air ratios from 1.4 to 1.6.•Maximum fuel-based specific impulse above 3000 s and thrust above 1500 N are measured.
A mathematical model for simulating combustion and detonation of a fuel–air mixture in the gas cavity above the free water surface is developed. The model is based on solving the conservation ...equations of mass, momentum, and energy for a two-phase reacting gas–water medium with the phases treated as interacting interpenetrating continua having their own values of velocity, temperature, and turbulence characteristics. The model is validated by laboratory experiments. The test rig included a transparent cylindrical tube with one closed-end, a pool with an optically transparent window, as well as power, ignition, control, and measurement systems. The tube was vertically immersed with its open end in water and filled with a gaseous explosive mixture. In the experiments, a stoichiometric propane–air mixture was ignited and burned in the semi-closed 60 mL cylindrical volume above the free surface of water. The model is shown to predict satisfactorily the lift force acting on the tube, the time history of pressure in the volume, and the dynamics of the flame and gas–water interface motion during combustion in the volume. The model is intended to be applied for the design of boats with propulsion solely by combustion/detonation of fuel–air mixture in cavities constructed into a bottom surface of the boat. This propulsion system replaces conventional propellers, thereby reducing hydrodynamic resistance.
Using wire-arc additive manufacturing (WAAM), we produced samples of Al–Co–Cr–Fe–Ni high-entropy alloy (HEA) with a grain size of 4–15 µm. Inclusions of the second phase were found along the ...boundaries and in the volume of the grains. The near-boundary volumes of the alloy (volumes located along grain boundaries) are enriched in chromium and iron atoms, the volume of grains is enriched in nickel and aluminum atoms, and cobalt is quasi-uniformly distributed in the alloy. The inclusions of an elongated shape are enriched in chromium, iron, and oxygen atoms and may be carbides. Microhardness, modulus of elasticity, and tribological properties of the alloy are determined and the stretch curves are analyzed. Irradiation of the HEA with a pulsed electron beam is accompanied by the release of grain boundaries from precipitates of the second phase, which indicates the homogenization of the material. High-speed crystallization of the molten surface layer of HEA samples is accompanied by the formation of a columnar structure with a submicrometer-nanocrystalline structure. The electron-beam processing decreases the microhardness of the surface layer of the alloy with a thickness of up to 90 µm, which may be due to the relaxation of internal stress fields formed in the initial material during its manufacture. Irradiation of a high-entropy alloy with an intense pulsed electron beam improves the strength and plasticity of the material, increasing the compressive strength by 1.1–1.6 times.
The air-breathing pulsed detonation thrust module (TM) for an aircraft designed for a subsonic flight at a speed of up to 120 m/s when operating on a standard aviation kerosene was developed using ...the analytical estimates and parametric multivariant three-dimensional (3D) calculations. The TM consists of an air intake with a check valve, a fuel supply system, a prechamber-jet ignition system and a combustion chamber with an attached detonation tube. An experimental sample of TM was fabricated, and its firing tests were carried out on a test rig with a thrust-measuring table. In firing tests, TM characteristics are obtained in the form of dependencies of effective thrust, aerodynamic drag and fuel-based specific impulse on fuel consumption at different speeds of the approaching air flow. It has been experimentally shown that the fuel-based specific impulse of the TM reaches 1000-1200 s, and the effective thrust developed by it reaches 180–200 N.
Hitherto unknown class of
N
-vinylpyrrolyl acrylic acids, multifaceted monomers and prospective building blocks for fine organic synthesis, has been prepared. The chemistry is based on the ...fundamental works of Academician B.A. Trofimov, which allowed synthesis of the inexhaustible family of
N
-vinylpyrroles.
The physical and mathematical model for simulating combustion and detonation of fuel mixture in the semi-confined gas volumes above the free surface of water is applied for modeling the transient ...two-phase reactive flow in the gas cavity under the bottom of a ship/boat. With the proper organization of the combustion/detonation process in the gas cavity, thermal expansion of combustion products can provide an additional lifting force that reduces the area of contact of the boat bottom with water, as well as a propulsive force caused by the overpressure of combustion/detonation products on redans—vertical sections of the boat bottom. The model is validated on the set of laboratory experiments with pulsed combustion of propane–air mixture in a semi-closed gas cavity. The model is shown to predict satisfactorily the arising lifting and propulsive forces acting on the volumes, the time histories of pressure in the volumes, and the dynamics of flame and gas–water interface motion during combustion in the volumes. For further model validation in terms of its scaling capability, a set of preliminary experiments with a larger-scale (by a factor of at least 5) towed boat with a bottom gas cavity were conducted on open water. In the experiment, the hydrogen–air mixture was ignited and burned in the bottom gas cavity in a pulsed mode. These experiments confirmed that pulsed combustion of fuel–air mixture in a gas cavity under the boat bottom creates positive propulsive and lifting forces acting on the boat. Moreover, in some experiments a considerable increase in the propulsive force was registered due to flame acceleration causing a higher overpressure in the cavity. The elevated values of the propulsive force in these conditions can be treated in favor of a pulsed detonation mode, which will be studied later.
Crystalline properties of (1–2)-μm-thick AlN buffer layers grown by plasma-assisted molecular-beam epitaxy (PA MBE) on c-Al2O3 substrates with different AlN nucleation layers have been studied. The ...best quality layers are obtained on 50-nm-thick nucleation AlN layers grown by a migration enhanced epitaxy (MEE) at substrate temperature of 780°C. In this case the buffer layers possess the lowest FWHM values of the symmetric AlN(0002) and skew symmetric AlN(10–15) x-ray rocking curve peaks of 469 and 1025arcsec, respectively, which correspond to the screw and edge threading dislocation densities of 4.7×108cm−2 and 5.9×109cm−2. This improvement seems to be related with the larger diameter of the flat-top grains in the AlN nucleation layers grown in the MEE mode at high substrate temperatures.
► High temperature MEE AlN nucleation layer is the best for PA MBE of AlN buffer layers. ► The initial lateral grain size influences on the TD densities in the AlN buffer layers. ► Incomplete stress relaxation was revealed in MEE AlN layers by XRD measurements.
Impact of high temperature electron irradiation on the characteristics of power silicon carbide-based semiconductor devices was studied for the first time. Commercial 4H–SiC integrated Schottky ...diodes (JBS) with blocking voltage of 1700 V were irradiated with 0.9 MeV electrons at temperatures from 23 to 5000С in the fluence range Φ from 1 × 1016 cm−2 to 1.3 × 1017 cm−2. It was shown that ruggedness of the diodes during high temperature (“hot”) irradiation significantly exceeds the ruggedness of diodes at room temperature (“cold”) irradiation. With an increase in the irradiation temperature from 23 to 500 °C, the change in the base resistance at a fluence of 1.3 × 1017 cm−2 decreases by 6 orders of magnitude. In the entire investigated range of irradiation temperatures and fluences, irradiation does not change the height of the metal-semiconductor barrier even at the maximum fluence Φ.
•1700 V blocking voltage 4H–SiC Schottky diodes.•High temperature (up to 500 C) 0.9 MeV electron irradiation.•Dose range from 1 × 1016 cm−2 to 1.3 × 1017 cm−2.•The change in the base resistance by 6 orders of magnitude.•Irradiation does not change the height of the metal-semiconductor barrier.
Experimental studies of an axisymmetric hydrogen-fueled detonation ramjet model 1.05-m long and 0.31 m in diameter with an expanding annular combustor were performed in a pulse wind tunnel under ...conditions of approaching air stream Mach number ranging from 4 to 8 with the total temperature of 290 K. In a supersonic air flow entering the combustor, continuous and longitudinally pulsating modes of hydrogen detonation with the corresponding characteristic frequencies of 1250 and 900 Hz were obtained. The maximum measured values of fuel-based specific impulse and total thrust were 3600 s and 2200 N.
•Compact hydrogen-fueled detonation ramjet is designed and tested in wind tunnel.•1-m long 0.3-m i.d. ramjet comprises M5 air intake and expanding annular combustor.•Stable spinning and pulse modes of hydrogen detonation at M4 to M8 are obtained.•Total positive force of 100 N acting on ramjet at M8 has been registered for the first time.•Maximum fuel-based specific impulse of 3600 s is measured at M6.
