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The research results conducted on binderless tungsten carbide (WC) ceramics obtained by Spark Plasma Sintering (SPS) of WC powders with different average particle sizes (0.095, 0.8, 3 μm) are presented. Nonuniform distribution of crystalline phases and microstructure of the WC ceramics was studied using layer-by-layer XRD analysis and SEM. Surface layers of the WC-based ceramics are characterized by nonuniform distribution of W2C crystalline phase and grain sizes, including the appearance of abnormally large grains. Thickness of the nonuniform layer was at least 50 μm. The effect under study is associated with an intense carbon diffusion from graphite foil. On the one hand, this contributed to a decrease in the intensity of W2C phase particle formation, which is transformed into α-WC phase due to the carbon. On the other hand, it caused abnormal grain growth in the layer where the carbon diffused. The obtained value of the carbon diffusion depth exceeds the values known from the literature (up to 1 μm in the case of volume diffusion even at temperature of 2370℃ and exposure time of ~ 60 h). The use of boron nitride (BN) as a protective coating on graphite mold parts did not prevent the formation of nonuniform layer on the ceramic surface.

This paper investigates the density, phase composition, microstructure and mechanical properties (microhardness, fracture toughness) of binderless WC + SiC ceramics obtained by conventional pressureless sintering (CPS) and Spark Plasma Sintering (SPS). α-WC nanopowders obtained by DC arc plasma chemical synthesis and β-SiC powders have been used as raw materials. The content of SiC particles was 1, 3, 5% wt. Excess graphite (0.3, 0.5% wt.) was added to α-WC nanopowders to decrease the volume fraction of W2C particles that negatively affect the mechanical properties of ceramics. WC + 1% wt. SiC + 0.3% wt. C ceramics are shown to have a homogeneous fine-grained microstructure, high relative density, increased microhardness and Palmquist fracture toughness. The CPS and SPS activation energies of WC + SiC nanopowders at an intensive shrinkage stage are determined using the Young-Cutler model. The effect of carbon and SiC particles on the CPS and SPS activation energies of tungsten carbide nanopowders has been analyzed. The CPS activation energies of WC, WC + C and WC + SiC + C nanopowders are shown to be closer to the carbon diffusion activation energy along α-WC grain boundaries. The SPS activation energies of WC and WC + SiC nanopowders turn out to be lower than the carbon grain boundary diffusion activation energy of α-WC.

Triphenylbut-2-enyl- (1a) and triphenylmetoxymethylphosphonium (1b) hexachlorozirconates have been synthesized by the reactions of zirconium tetrachloride with the triphenylalkylphosphonium chlorides in acetonitrile for the first time and characterized by the IR, NMR spectroscopy and X-ray analysis. The most intensive bands in IR spectra correspond to the valence vibrations of the CAr-H and the СAr-СAr bonds in the triphenylalkylphosphonium cations. The splitting of carbon atoms signals is observed due to the presence of 13C – 31P coupling. SSCC for carbon atoms directly connected with phosphorus are about 48–85 Hz. According to the X-Ray data, compound 1a crystallizes in the monoclinic crystal lattice (the P21/c space symmetry group). Hexachlorozirconate 1b forms the triclinic crystals belong to the P-1 space symmetry group. Crystals of compound 1a is characterized by the less dense molecular packing in the crystal lattice in comparison with compound 1b. Calculated densities for the structures 1a,b are 1.355 g/cm3 and 1.466 g/сm3, respectively. Structural organization of the complexes in crystals is caused by the formation of hydrogen bonds between chlorine atoms of the anion and hydrogens of phenyl and alkyl groups of the cations. The phosphorus atoms in the triphenylalkylphosphonium cations have distorted tetrahedral coordination (CPC 107.01(4)°-114.10(6)° for 1а, 107.38(9)°-112.06(7)° for 1b, the P-С bonds are 1.790(14)-1.865(14) Å for 1а, 1.7838(12)-1.8293(18) Å for 1b). In centrosymmetric octahedral anions [ZrCl6]2− (trans-ClZrCl 180°) the Zr-Cl distances are 2.4654(15)-2.4952(17) Å for 1а and 2.4641(14)-2.4711(12) Å for 1b.

The article discusses postglacial landscape transformation in the Northern Hemisphere Middle Pleistocene glaciation area located in the center of the Russian Plain. We attempted to verify the regional paleogeographic model by reconstructing the Late Pleistocene incision-infill cycles at the Eastern Borisoglebsk Upland based on a comparison of inactive interfluves headwaters and actual fluvial network palaeoarchives. The study was also aimed to determine the past extent of fluvial systems. Interdisciplinary research of the actual and buried topography, lithology and pedogenic properties of surface deposits was carrid out with remote sensing data interpretation, DGPS survey, and detailed description of geological cores involved. The study was followed by analysis of grain size, chemical and organic contents, microstructure, and numerical dating. Integrating the available results, we propose a scenario of the fluvial network transformation at the Eastern Borisoglebsk Upland over the last 150 ka. At least four fluvial incision stages were determined while network extent has significantly changed through the Late Pleistocene. Three can be generally associated with the regional base level decrease – Late Moscow, Late Valdai and Late Holocene and accompanying isolation of the Nero Lake terraces of 130 m, 100–105 m and 95–98 m. Incision stages were separated by landscape stability or aggradation periods those were asynchronous at the middle and upper parts of the fluvial network. The main agent of initial valley infill appears to be local lacustrine sedimentation altered by alluvial and colluvial deposition towards the second half of Valdai. Revealed landscape conditions variability emphasize the importance of comprehensive local correlations for regional retrospective models. Keywords: Interfluve headwaters, Fluvial, Incision-Infill Cycle, Pleistocene

The study of one-dimensional coordination polymers {Hg2Cl4L1}n (1), {HgBr2L1}n (2) and {Hg2Cl4L2}n (3) (L1 = (S)P(OC2H5)2NHC6H4NHP(S)(OC2H5)2 and L2 = (S)P(OC2H5)2NC4H8NP(S)(OC2H5)2) is the first such structural study of Hg(II) coordination polymers with (O)2(N)PS-based ligands. The mercury atoms adopt a distorted trigonal pyramidal environment, Hg(Cl)3(S) for 1 and 3 and Hg(Br)2(S)2 for 2, and the difference observed in the stoichiometry of mercury halide to the thiophosphoramide ligand in 1 and 3 with respect to the one in 2 is a result of the formation of the Hg2Cl2 ring, however, the molar ratio 2 : 1 of HgX2 (X = Cl and Br) to ligand was used for the preparation of all three complexes. The strengths of mercury-sulfur and mercury-halide covalent bonds are evaluated by theoretical calculations (QTAIM and NBO) which show their principally electrostatic nature with a partial covalent contribution. The energies of interactions building supramolecular assemblies and intramolecular interactions, i.e. NH⋯Cl, NH⋯Br, CH⋯Cl, CH⋯Br, CH⋯O, CH⋯S and CH⋯π, are theoretically evaluated. The characteristic structural features arising from the aromatic/aliphatic linkers in the ligands and chloride/bromide attached to mercury are investigated by Hirshfeld surface analysis and fingerprint plots.

Methyltriphenylphosphonium dicyanodibromoaurate (1) [Ph3PMe]+[Au(CN)2Br2]- was synthesized by the reaction of potassium dicyanodibromoaurate with methyltriphenylphosphonium bromide in an aqueous solution and was structurally characterized. The complex is a yellow-col-ored, air-resistant crystalline substance with a clear melting point. The structure of the compound was established by IR spectroscopy, NMR spectroscopy and X-ray diffraction analysis. An intense absorption band was observed in the IR spectrum of compound at 2220 cm-1, corresponding to the stretching vibrations of cyano groups. The absorption band of the deformation vibrations of the P-SPh bonds in the IR spectrum is at 1438 cm-1. In the recorded 1N, 13S, and 31R NMR spectra, signals are observed for the number, value of chemical shifts and integral intensity that do not contradict the proposed complex structure. The X-ray diffraction analysis of crystal 1 was carried out on a Bruker D8 QUEST diffractometer (MoKα radiation, λ = 0.71073 A, graphite monochrom-ator). [C21H18AuBr2N2P, M = 686.13, crystal system triclinic, space group P-1, a = 8.802(5), b = 8.989(5), c = 15.233(11) A, V = 1143.8(13) A3, Z = 2, μ = 10.002 mm-1, F(000) = 644, crystal size 0.41x0.30x0.22 mm]. According to the X-ray diffraction analysis (XRDA) data there are two types of centrosymmetric crystallographically independent monomeric dicyanodibromoaurate anions and methyltriphenylphosphonium cations in the crystal of compound MFDDA. The cations have a distorted tetrahedral configuration: the CPC angles equal 108.8(2)°-110.0(2)°, the P-S distances are 1.791(5)-1.800(5) A. All SAuC and BrAuBr trans-angles are 180.0° in the [Au(CN)2Br2]-an-ions. The Au-C distances in anions differ from each other and equal 2.040(7), 2.024(1), 1.991(2) A. These values are close to the sum of the covalent radii of atoms (2.03 A). The Au-Br bond lengths are equal to 2.4162(14), 2.4591, 2.474(5) A in dicyanodibromoaurate anions. Formation of the crystal structure occurs due to formation of weak N···N-S hydrogen bonds between cations and anions (2.68, 2.59, 2.38 A) and Br···N-S (3.03, 3.02 A). Complete tables of coordinates of atoms, bond lengths and valence angles are deposited at the Cambridge Crystallographic Data Centre. © 2020, Ivanovo State University of Chemistry and Technology. Ministry of Education and Science of the Russian Federation, Minobrnauka: 4.6151.2017/8.9 South Ural State University is grateful for the financial support of the Ministry of Education and Science of the Russian Federation (grant No. 4.6151.2017/8.9).

The study of one-dimensional coordination polymers {Hg

In the structure of 2-(4-chloroanilino)-1,3,2λ4-diazaphosphol-2-one, C12H11ClN3OP, each molecule is connected with four neighbouring molecules through (N—H)2...O hydrogen bonds. These hydrogen bonds form a tubular arrangement along the [001] direction built from R 3 3(12) and R 4 3(14) hydrogen-bond ring motifs, combined with a C(4) chain motif. The hole constructed in the tubular architecture includes a 12-atom arrangement (three P, three N, three O and three H atoms) belonging to three adjacent molecules hydrogen bonded to each other. One of the N—H groups of the diazaphosphole ring, not co-operating in classical hydrogen bonding, takes part in an N—H...π interaction. This interaction occurs within the tubular array and does not change the dimension of the hydrogen-bond pattern. The energies of the N—H...O and N—H...π hydrogen bonds were studied by NBO (natural bond orbital) analysis, using the experimental hydrogen-bonded cluster of molecules as the input file for the chemical calculations. In the 1H NMR experiment, the nitrogen-bound proton of the diazaphosphole ring has a high value of 17.2 Hz for the 2 J H–P coupling constant.

Borisoglebsk Upland is considered an example of a secondary upland plain in the marginal zone of the last Middle Pleistocene glaciation. Moraine hills and kames were reworked by glaciofluvial processes and incised by small fluvial forms later. Its postglacial surface drift cover is regularly defined as an undivided complex of mantle loams of dominantly subaerial origin with characteristic cryogenic features and remnants of paleosols. However, some previous studies suggest that lake sedimentation played an important role in the postglacial history of the Borisoglebsk Upland. This paper presents results of a detailed investigation of postglacial sedimentary cover of the eastern part of the Borisoglebsk Upland aimed to reconstruct the co-evolution of surface deposits, soil cover and geomorphic landscapes since degradation of the last Middle Pleistocene glaciation about 150 ka (MIS-6). The study is essentially based on a comprehensive lithological, pedological and geocryological description of postglacial deposits in cores (hand or machine-driven) and open sections, systematic sampling for grain size analysis and selective sampling for 14C absolute dating and monoliths structural examination. The results indicate that most of the surface drifts in this feature consists of stratified lacustrine deposits. Their Late Pleistocene age is stratigraphically confined by the underlying paleosols and incorporated peats of the Mikulino interglacial age (MIS-5) and several organic-rich layers within the lake sequence 14C dated to the Middle Valdai interstadial (MIS-3). Overlying mantle loams and colluvial deposits with cryogenic features and low organic matter content those facially substitute lacustrine sediments were attributed to the Late Valdai stadial (MIS-2). After the Mid-Holocene stabilization, relatively thin colluvial cover identified by the increased amount of organic matter also deposited. We conclude that lacustrine sedimentation is the primary Late Pleistocene agent that transformed the initial glacial topography and most characteristic type of lithodynamics of the eastern Borisoglebsk Upland.

Postglacial fluvial network history of the central Russian Plain is complex and heterogeneous regarding both temporal framework and leading development agents. Modern valley systems inherit many relic features including excessively large width inconsistent with present runoff conditions, highly elevated terraces (both depositional and erosional), thick bottom sedimentary infills partly incised by modern gullies, inactive headwaters almost infilled and disconnected from the presently active fluvial network, etc. Such distinct footprints can be related to much higher intensities of fluvial and other associated processes in the past.

During the Holocene, interfluvial landscapes of European plains have experienced alternating periods of relative stability and significant shifts in climate, soil and geomorphological development. Assumed to be an arena of major transformation their evolutionary model is not entirely resolved yet. Based on lithostratigraphic, geomorphologic and soil survey, new results on the Holocene dynamics of fluvial and related processes including landscape stabilization phases for one of the gully catchments draining the Borisoglebsk Upland northeastern slope towards the Nero Lake are presented. Common absence of the early Holocene deposits can be explained by generally negative sediment budget of the catchment. Nevertheless, continuous erosion was not likely whether rare climatic extremes probably were the case. A series of middle Holocene dates obtained by analyzing total organic carbon from organic-accumulative layers of buried soils, lake gyttja and peats highlights strong evidence of the synchronous phase of landscape stabilization in both upper and lower parts of the Puzhbol catchment accompanied by active infilling of small erosion cuts in its middle part. The upper part of the Puzhbol Gully fan sediment shows clear evidence of synchronous accumulation of agrogenic colluvium and gully alluvium since XIIth Century on top of the lake terrace deposits.

Parameters of powder WC + 10% Co sintering modes that exclude the possibility of η-phase (Co3W3C) formation were determined. The phase composition was controlled by introducing colloidal graphite into the original powder.

In the crystal structure ofO,O′-diethylN-(2,4,6-trimethylphenyl)thiophosphate, C13H22NO2PS, two symmetrically independent thiophosphoramide molecules are linked through N—H...S and N—H...π hydrogen bonds to form a noncentrosymmetric dimer, withZ′ = 2. The strengths of the hydrogen bonds were evaluated using density functional theory (DFT) at the M06-2X level within the 6-311++G(d,p) basis set, and by considering the quantum theory of atoms in molecules (QTAIM). It was found that the N—H...S hydrogen bond is slightly stronger than the N—H...π hydrogen bond. This is reflected in differences between the calculated N—H stretching frequencies of the isolated molecules and the frequencies of the same N—H units involved in the different hydrogen bonds of the hydrogen-bonded dimer. For these hydrogen bonds, the corresponding charge transfers,i.e.lp (or π)→σ*, were studied, according to the second-order perturbation theory in natural bond orbital (NBO) methodology. Hirshfeld surface analysis was applied for a detailed investigation of all the contacts participating in the crystal packing.

The reaction between pentaphenylantimony and meta-carboranedicarboxylic acid in benzene leads to the title compound that was characterized by X-ray diffraction data.

In the title mol-ecule, [Bi(C6H5)3(C4H5O2)2], the Bi(V) atom is in a distorted trigonal-bipyramidal environment with carboxyl-ate O atoms in axial positions and phenyl C atoms in the equatorial plane. The Bi-O bond lengths are 2.283 (3) and 2.309 (2) Å, but as a result of additional long Bi⋯O inter-actions [2.787 (3) and 2.734 (3) Å], one of the C-Bi-C angles is 148.62 (13)°. In the crystal, weak C-H⋯O hydrogen bonds connect pairs of mol-ecules into inversion dimers. These dimers are further connected by weak C-H⋯π inter-actions into chains along [100] .

The asymmetric unit of the title compound, [Sb(C6H5)3(C10H9O3)2]·C6H6, contains one organometallic molecule and one benzene molecule that is disordered over two sets of sites with an occupancy ratio of 0.556 (15):0.444 (15). The SbV atom is in a distorted trigonal–bipyramidal environment with the carboxylate O atoms in axial positions and phenyl C atoms in the equatorial plane. As a result of additional Sb...O interactions, one of the C—Sb—C angles is widened to 140.19 (6)°.

Space technology for manufacturing on an industrial scale of certain materials, and medicines of significantly higher quality. At present, space manufacturing of semiconductor materials for the electronic industry seems the most promising. Even in this decade the scale of production required may become considerable. The residual gravity aboard a spacecraft designed for various technological processes should not exceed 10{sup {minus}5}-10{sup {minus}6}g(g is the acceleration of free fall). The length of technological cycles may range from several hours to one month. Thermoelectric nuclear power generators offer much promise for use in industrial spacecraft, and in this paper, we discuss possible concepts for the application of thermoelectric nuclear power generators in industrial spacecraft, characterized by the following options for power supply and the logistics of loading the raw materials and unloading the manufactured products and the redelivery to earth: (1) automatic loading an unloading of the raw materials and products, (2) manual loading and unloading, and (3) energy supplied remotely to the industrial spacecraft from an autonomous power plant.

Power-generation and propulsion complexes for spacecraft, universal space platforms (US) which combine a power unit and high- and low-thrust propulsion unions, make it possible to efficiently solve problems involved in creating satellite communication systems, environmental monitoring systems, industrial technology platforms, interorbital shuttles, etc. Electrical power consumed by prospective spacecraft designed for communication or environmental monitoring may be as high as 20-30 kW. Manufacturing of semiconductors and biological materials in space may require electrical power of 30-l00 kW in the coming decades. The power required to transport loads between orbits using ion-plasma jet engines will amount to tens to hundreds of kilowatts. For all these missions, nuclear power units have important advantages over solar photoelectric power units in their mass, size, cost, and performance characteristics. There is a good reason to consider the use of thermoelectric Nuclear Power Generators (NPG) for USPs due to their small bulk, their capacity for generating greatly increased power in the high-power mode during 15-20% of the total length of the mission, and minimal disturbance of the motion of the spacecraft.

The parameters of a thermoelectric reactor are determined by the radial dimensions of the EGC, in particular the external diameter d{sub EGC}, the diameter d{sub e} of the emitter, and the diameter d{sub c} of the channel fuel core. In this paper we consider a promising design, employing a five-layer collector package, including the collector proper, an insulation layer operating in cesium vapor, a guard electrode, and a dry insulation layer, all enclosed in a casing in contact with the EGC coolant. The total thickness of the collector package is 2.2-2.5 mm, for a range of d{sub EGC} of 18-50 mm. Given a reactor lifetime of 5-7 years, the emitter shell is made of hardened tungsten alloys, alloyed with niobium in thermal reactors and with tantalum in fast reactors, for an average specific energy conversion in the EGC of w{sub av} - 2-3 W/cm{sup 2}. For any diameter, the inner volume of the fuel core should have sufficient porosity to provide for redistribution of the fuel swelling toward the inside of the core. To ensure a lifetime of 7 years, the temperature of the EGC emitters fuel core should be limited to 1600{degrees}C, which limits the average specific conversion power.more » For a shorter lifetime the average specific conversion power and the emitter temperature may be higher. As the diameters of the fuel core and the emitter unit increase, the maximum permissible deformation of the emitter unit during the lifetime varies inversely with the emitter diameter. The thickness of the emitter shell must then increase with d{sub e} in order to keep the swelling within limits. For values of d{sub e} of practical interest, the dependence of the thickness of the emitter shell on the diameter for uranium oxide can be described as a linear function. The calculation procedure presented in this article can be used when {delta}{sub e} can be expressed by any given function of the fuel core diameter.« less

Conceptual problems of development of two-mode multi-cell thermionic fuel element (TFE) for nuclear electric power and propulsion system are considered. The results of analysis of the design and TFE output parameters are presented. It is shown that application of advanced high effective materials and technologies provides operating of the TFE in two modes: a) in nominal mode of power generation for power supply of spacecraft payload at operational orbit and b) in forced mode of power generation for power supply of electric thrusters under spacecraft orbit transfer from intermediate to operational one.

In this study combination of thermionic space nuclear power systems (SNPS) and electrojet propulsion system (EJPS) forming power and propulsion complex is considered for missions with the goals of deep space exploration. SNPS and EJPS are described, their power and mass parameters are presented and the possibilities of this combination are analyzed.

In the report the principles of nuclear power and propulsion complex (NPPC) construction are presented. NPPC considered can ensure the time of spacecraft transfer to geostationary orbit (GSO) within 1 year under electric power level no less than 40 kW at prolonged nominal mode on GSO for spacecraft loads feeding. The main power and mass and dimension performances of such NPPC are summarized. Analysis of relationship between spacedraft mass, its mission payload and transfer time also and a number of main NPPC parameters is performed. The conclusion is made about considerable promises of the NPPC for creating future satellite multi‐purpose systems by using PROTON‐ and TITAN‐class launch vehicles.

The possible schemes of space nuclear power systems (SNPS) with out‐of‐core thermionic generator (TIG) are discussed. In connection with essential progress in technology of thermionic converters (TIC) with small (of order several micrometers) interelectrode gap operating at quasi vacuum mode and ensuring sufficiently high electric parameters under emitter temperature 1373...1473 K the SNPS scheme with heat transfer from reactor to TIC by liquid metal (lithium) circulating coolant is the most promising one. Conformably to this scheme principal concept propositions on which development of these SNPS must be based are given, SNPS design scheme and operation are described, SNPS main power and mass and dimension performances are presented.

One of the important future space technologies is the space production of semiconductive substances, composite materials, medical preparations and so on. Required for this electric power will equal 20–50 kW in nearest ten‐year period with further increasing to one hundred and more kilowatt. For similar production spacecrafts the application of thermionic space nuclear power (SNPS) can be perspective because these systems have a number of important advantages as compared with solar systems for spacecrafts of this type. The possible application concepts of thermionic SNPS with electric power 25 to 30 kW production spacecrafts are considered including the next versions: automatic loading and unloading of raw materials and products; loading and unloading executed by cosmonauts when SNPS being as a part of spacecraft and its demating from spacecraft during the process fulfillment; remote power transmission for power supply of production spacecrafts. It is shown that all considered versions thermionic SNPS can provide power supply of production spacecrafts with satisfying necessary operation requirements.

Choice of coolant type (Na‐K eutectic alloy of Li) for thermionic space nuclear power systems (SNPS) has been considered from viewpoint of power required for coolant pumping. It is shown that the choice depends upon SNPS output electric power and by increasing its power to acertain level the transition from Na‐K eutectic alloy to Li is expedient. For in‐core thermionic reactor (ITR) used in SNPS with certain type of coolant the optimal specific power corresponding to SNPS maximal output electric power exists under forcing ITR specific electric power. For certain type of coolant the coolant heating in ITR corresponding to SNPS optimal output electric power exists also. The expressions for these optimal values are given.

Choice of unified optimal radial dimensions for thermionic fuel elements (TFE) is considered for the use of TFE with five‐layer collector assembly in in‐core thermionic reactors (ITR) on thermal and fast neutrons of space nuclear power systems (SNPS) with long (no less 5 years) lifetime and ITR electric power in the range from 30 to 300 kW. A series of optimum conditions has considered taking into account ITR core volume, given values for area of ITR emission surface and ItR effective multiplication factor, characteristics of core structure (average moderator portion in core of ITR on thermal neutrons, fuel pin porosity, coolant portion in core and so on), TFE hookup in thermionic generator and so on.On the base of analysis of these conditions the conclusion has made that in aforesaid range of ITR electric power the TFE optimal radial dimensions unified for use in ITR on both thermal and fast neutrons is in the range: TFE external diameter is from 22 to 25 mm, fuel diameter from 15, 5 to 17,5 mm. Under greater electric power the to lesser radial dimensions is expedient.

The paper considers the concept of power propulsion systems‐universal space platforms (USPs) on the basis of second‐generation thermionic nuclear power system (NPSs) and stationary plasma electric thrusters (SPETs). The composition and the principles of layout of such a system, based on a thermionic NPS with a continuous power of up to 30 kWe allowing power augmentation by a factor of 2–2.5 as long as during a year, as well as SPETs with a specific impulse of at least 20 km/s and a propulsion efficiency of 0.6–0.7 are discussed. The layouts and the basic parameters are presented for a power propulsion system ensuring cargo transportation from an initial radiation‐safe 800 km high orbit into a geostationary one using the ‘‘Zenit’’ and ‘‘Proton’’ launch systems for injection into an initial orbit. It is shown that the mass of mission‐oriented equipment in the geostationary orbit in the cases under consideration ranges from 2500 to 5500 kg on condition that the flight time is not longer than a year.The power...

The region of expedient using of SNPS with in‐core thermal thermionic reactor (ITR) is limited by electric power level of about 100 kWe under SNPS lifetime from 3 to 5 years. At the same time the reactor power may be forced from two to three times during the period of about half a year. The mathematical model of SNPS mass dependence on a degree of forcing is given. The results of calculation of payload masses and transfer times for transfer from low orbit to geostationary orbit for two thermal reactors having emission area 1.6 m2 and 2.5 m2 are given for different types of electrojets.

The electric power of thermionic SNPS with thermal reactor is limited to about 100 kWe under lifetime of 5 or more years. The possible conceptual designs of this thermionic SNPS and its basic units are described. The mass optimization had carried out for different SNPS conceptual designs and permissible levels of ionizing radiation. The optimal lengths from the core center to the user interface module plane had defined. The dependence of specific mass of this optimized SNPS on the electric power in the range from 15 to 60 kWe under permissible radiation dozes from 105 to 106 rad are given.