We present the results of simulations and experimental studies of a W-band surface-wave oscillator powered by a ribbon high-current relativistic electron beam produced by SINUKI accelerator (IAP RAS, ...Nizhny Novgorod, 1 kA / 650 keV / 17 ns). Planar geometry of the interaction space facilitates efficient mode selection over wide transverse coordinate by using open waveguide at fairly large oversize factor (the width of the waveguide is ~ 8 wavelengths). Stable oscillation regime is obtained at frequency of 75 GHz with a pulse duration of about 5 ns. The output power measured by the calorimetric method reaches 25 MW.
Radiolytic (8 MeV electron beam, 0.1–2 MGy dose) and post-radiation (3-years aging) transformations in tri-n-butyl phosphate/Isopar-M radiochemical extraction medium saturated with 3.4 M nitric acid ...are described. The products of nitration, nitroxylation, hydroxylation, dealkylation, carbonylation, carboxylation, and radical dimerization have been identified, and the mechanism of their formation and post-radiation redistribution has been analyzed. The competition between the processes caused by radiolysis, acid hydrolysis, nitration and nitroxylation is discussed. The results indicate an increase in the effect of chemical and physical protection of tri-n-butyl phosphate with an increase in the absorbed dose.
•Hydrolysis is inferior to radiolysis in the efficiency of TBP degradation.•Post-radiation aging promotes the formation of nitroesters at low pH.•Isopar-M protects TBP without increasing the explosiveness of its mixtures.•The chemical and physical protection of TBP increases with the absorbed dose.
We consider the problem of interaction of three charged particles, the size of one of which can be disregarded. The equations for the expansion coefficients of the electric field potential are ...derived using the method of expansion in spherical harmonics. Expressions are obtained for the Cartesian components of the interaction force and the torque due to this force. It is shown that in spite of the axial symmetry breaking after the addition of the third particle, if the free charge is distributed uniformly over the surface of a spherical particle, all vector components of the torque acting on this particle are equal to zero. By separating the contributions from image charges in explicit form, we have derived the expressions for the surface charge density and the force of interaction of the particles. The conditions for the emergence of attraction between similarly charged spherical particles depending on the position of the point particle are investigated.
•A bimodal distribution of aerosol on Mars has been inferred from solar occultations.•The coarser mode is represented by both dust and H2O ice particles with average radius of 0.7 and 1.2μm.•The ...finer mode with a radius of 0.04–0.07μm has been detected in both hemispheres.•The lack of condensation nuclei could not fully explain the high water supersaturation.•The finer mode is unstable against coagulation and requires a continuous source of particles to be maintained.
First simultaneous analysis of the ultraviolet (UV) and infrared (IR) atmospheric extinctions from SPICAM/Mars Express solar occultations in the beginning of the Northern summer (Ls=56–97°) is presented. The two SPICAM channels allow sounding of the martian atmosphere in the spectral range from 0.118 to 1.7μm at the altitudes from 10 to 80km. Based on Mie scattering theory with adequate refraction indices for dust and H2O ice, a bimodal distribution of aerosol has been inferred from the SPICAM measurements. The coarser mode is represented by both dust and H2O particles with average radius of 0.7 and 1.2μm, respectively, with number density from 0.01 to 10 particles in cm3. Clouds belonging to the aphelion cloud belt have been observed in midlatitudes in the Southern and the Northern hemispheres at altitudes of 20–30km. The clouds are formed of large particles, and their opacity in the UV and the IR is below 0.03. The finer mode with a radius of 0.04–0.07μm and a number density from 1cm−3 at 60km to 1000cm−3 at 20km has been detected in both hemispheres. In the Southern hemisphere the finer mode extends up to 70km, whereas in the Northern hemisphere it is confined below 30–40km. The lack of condensation nuclei is consistent, but could not fully explain the high water supersaturation observed between 30 and 50km in the same Northern hemisphere dataset (Maltagliati L., Montmessin, F., Fedorova, A., Korablev, O., Forget, F., Bertaux, J.-L. 2011. Science 333, 1868–1871). The average size of the fine mode (∼50nm) and the large number density (up to 1000cm−3) most likely corresponds to Aitken particles (r<0.1μm). This mode is unstable against coagulation and requires a continuous source of particles to be maintained, at least one order of magnitude more than estimations for the meteoric flux. A possible source is the dust lifting from the surface and dust devils. A detailed microphysical modeling is required to study the probability of survival of the observed bimodal distribution.
In this paper, we construct a mathematical model for estimating the mass of water flooding the coastline of a basin. The models of the relief of the bottom of the basin and the relief of the flooding ...part of the coastline are constructed by stochastic methods. The simulation is based on empirical data of measurements of depths of the basin and the study of level lines on maps of the coastal zone. The equations of the surface relief of the coastal zone are constructed by using empirical data from maps with level lines.
The results of a search for individual fast radio bursts with the Large Phased Antenna of the Lebedev Physical Institute at 111 MHz during July 2012 through August 2018 are presented. The signals ...were distinguished by convolving the data with a template with a fixed form, followed by convolution with test dispersion measures. Areas of sky containing the galaxies M31 and M33 were chosen for the search. Three radio bursts were detected in the vicinity of M33, five in the vicinity of M31, and one in a region offset from the center of M31 by an hour in right ascension. The dispersion measures of the detected bursts range from 203 to 1262 pc/cm
3
.
The thermal stability of dibenzo-21-crown-7 and of MN-200 organic matrix based on styrene–divinylbenzene in inert and oxidizing atmosphere at temperatures of up to 600°С was studied. Solid ...extractants (SEs) were prepared from these components. These SEs are stable up to 300°С in inert atmosphere and up to 180–250°С in oxidizing atmosphere, depending on the presence of an additional diluent, fluorinated alcohol, in the SE. At higher temperatures, the SEs undergo exothermic processes accompanied by the formation of such major gaseous products as toluene, styrene, benzaldehyde, 1-ethyl-4-methylbenzene, and 1,3-dioxolane. Their yield depends on the type of the gaseous atmosphere used.
The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared ...spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm
−1
. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described.
The concept of next-generation spherical tokamak is being considered: the Globus-3 project, which, in its characteristics, is compatible with the infrastructure existing at the Ioffe Institute, but ...differs from the currently operating Globus-M2 tokamak in the stronger toroidal magnetic field (1.5–3.0 T) and increased duration of plasma discharge. The parametric analysis data are presented that determined the preliminary selection of the facility parameters. Three options for the electromagnetic system were considered: with the warm copper coils, with the pre-cooled copper coils and with the coils made of high-temperature superconductors. For the first option, the concept for designing the electromagnetic system and vacuum vessel of the facility has been developed. The basic shot scenario with duration of up to 3 s at the field of 1.5 T and plasma current of 0.8 MA is presented.
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.
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