Nonlinear dynamics of beta induced Alfv\'en eigenmode driven by energetic particles

Nonlinear saturation of beta induced Alfv\'en eigenmode, driven by slowing down energetic particles via transit resonance, is investigated by the nonlinear hybrid magnetohyrodynamic gyro-kinetic code (XHMGC). Saturation is characterized by frequency chirping and symmetry breaking between co- and counter-passing particles, which can be understood as the the evidence of resonance-detuning. The scaling of the saturation amplitude with the growth rate is also demonstrated to be consistent with radial resonance detuning due to the radial non-uniformity and mode structure

Undamped electrostatic plasma waves

Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named {\it corner modes}. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the $(k,\omega_{_R})$ plane ($\omega_{_R}$ being the real part of the wave frequency and $k$ the wavenumber), away from the well-known `thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower $k$-values and chopping the tail shifts them toward higher $k$-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.Comment: 11 pages, 10 figure

Competitive complex of machinery and technologies for the production of grain and feed

The current situation in agricultural production is challenging. During the last 2 decades, the agrarian production system has been deteriorating. It concerns crop rotations, moisture accumulation and moisture conservation technologies, ways of increasing soil fertility and growing environmentally friendly grain, reducing production costs and increasing product profitability. But there are forced late sowings and artificial “drought”. All this provides reasons to consider domestic breeding and seed production obsolete and to introduce the foreign analogue, which has planned negative impacts not only on quantitative, but also on qualitative safety. The article provides the solution to this major strategic problem. Under the research program of the Russian Academy of Agricultural Sciences, a highly competitive technology for the production of grain and fodder was developed on the basis of only domestic equipment that 2-5 times predominates over the best foreign analogues in functional indicators. It was confirmed by a number of state tests in 1990-2016 and approved by numerous meetings of the Scientific and Technical Council of the Ministry of Agriculture of the Russian Federation, RAS. The units of domestic tractors and functional machines that can compete with the best foreign counterparts have been developed

Criticality in a Vlasov-Poisson system - a fermionic universality class

A model Vlasov--Poisson system is simulated close the point of marginal stability, thus assuming only the wave-particle resonant interactions are responsible for saturation, and shown to obey the power--law scaling of a second-order phase transition. The set of critical exponents analogous to those of the Ising universality class is calculated and shown to obey the Widom and Rushbrooke scaling and Josephson's hyperscaling relations at the formal dimensionality $d=5$ below the critical point at nonzero order parameter. However, the two-point correlation function does not correspond to the propagator of Euclidean quantum field theory, which is the Gaussian model for the Ising universality class. Instead it corresponds to the propagator for the fermionic {\it vector} field and to the {\it upper critical dimensionality} $d_c=2$. This suggests criticality of collisionless Vlasov-Poisson systems as representative of the {\it universality class} of critical phenomena of {\it a fermionic} quantum field description.Comment: 10 pages, 6 figures, Submitted to Phys. Rev.

ПОЧВООБРАБАТЫВАЮЩАЯ ТЕХНИКА: ПУТИ ИМПОРТОЗАМЕЩЕНИЯ

The group of scientists in Russian Academy of Sciences system has finished the next stage of creation, test and widespread introduction of import-substituting competitive machinery for antidroughty technology. They created the complex of technologically functional completely closed upgraded soil-cultivating and sowing machines for all soil climatic conditions in Russia. The offered technology with a complex of the domestic technics is more profitable than foreign one. Crops cultivation on this technology under drought conditions promotes reduction of import of main types of agricultural production. The foreign machines can not always operate on stubble fields in Russia. They are adapted only for prior soil tillage minimum technology. Domestic agrotechnologies with the machines complex adapted to local conditions, in comparison with the best foreign analogs, allow to increase twice productivity and yield, by 3 times to lower expenses of fuel and capacity requirement, by 4 times - metal consumption and by 5 times - resources. The developed technics complexes can be used for moisture-power-resource-saving environmentally friendly production technologies. The cumulative economic effect of use of the upgraded equipment on 1 million hectares of wheat makes 8-45 billion rubles.Коллектив ученых в системе РАН завершил очередной этап создания, испытания и широкого внедрения импортозамещающей высококонкурентоспособной техники для противозасушливой технологии. Создан комплекс технологически функциональной цельнозамкнутой модернизированной почвообрабатывающей и посевной техники для всех почвенных климатических условий России. Показано, что предложенная технология с комплексом отечественной техники рентабельнее зарубежной. Доказано, что выращивание сельхозкультур по данной технологии в условиях засухи способствует сокращению импорта основных видов сельскохозяйственной продукции. Установлено, что зарубежная техника не всегда может работать по стерне в полевых условиях агропредприятий России. Она приспособлена только для предварительной минимальной технологии обработки почвы. Отмечено, что отечественные агротехнологии с адаптированным к местным условиям комплексом техники, по сравнению с лучшими зарубежными аналогами, позволяют в 2 раза повысить производительность и урожайность сельхозкультур, в 3 раза снизить затраты топлива и потребность в мощности, в 4 раза - металлоемкость и в 5 раз - ресурсы. Разработанные комплексы техники могут быть использованы для влаго-, энерго-, ресурсосберегающих экологически чистых технологий производства продукции растениеводства. Показано, что общий экономический эффект от использования модернизированной техники на 1 млн га посева пшеницы составляет 8-45 млрд руб

Giant optical anisotropy in transition metal dichalcogenides for next-generation photonics

Large optical anisotropy observed in a broad spectral range is of paramount importance for efficient light manipulation in countless devices. Although a giant anisotropy was recently observed in the mid-infrared wavelength range, for visible and near-infrared spectral intervals, the problem remains acute with the highest reported birefringence values of 0.8 in BaTiS3 and h-BN crystals. This inspired an intensive search for giant optical anisotropy among natural and artificial materials. Here, we demonstrate that layered transition metal dichalcogenides (TMDCs) provide an answer to this quest owing to their fundamental differences between intralayer strong covalent bonding and weak interlayer van der Walls interaction. To do this, we carried out a correlative far- and near-field characterization validated by first-principle calculations that reveals an unprecedented birefringence of 1.5 in the infrared and 3 in the visible light for MoS2. Our findings demonstrate that this outstanding anisotropy allows for tackling the diffraction limit enabling an avenue for on-chip next-generation photonics.Comment: 20 pages, 5 figure

Exploring van der Waals materials with high anisotropy: geometrical and optical approaches

The emergence of van der Waals (vdW) materials resulted in the discovery of their giant optical, mechanical, and electronic anisotropic properties, immediately enabling countless novel phenomena and applications. Such success inspired an intensive search for the highest possible anisotropic properties among vdW materials. Furthermore, the identification of the most promising among the huge family of vdW materials is a challenging quest requiring innovative approaches. Here, we suggest an easy-to-use method for such a survey based on the crystallographic geometrical perspective of vdW materials followed by their optical characterization. Using our approach, we found As2S3 as a highly anisotropic vdW material. It demonstrates rare giant in-plane optical anisotropy, high refractive index and transparency in the visible range, overcoming the century-long record set by rutile. Given these benefits, As2S3 opens a pathway towards next-generation nanophotonics as demonstrated by an ultrathin true zero-order quarter-waveplate that combines classical and the Fabry-Perot optical phase accumulations. Hence, our approach provides an effective and easy-to-use method to find vdW materials with the utmost anisotropic properties.Comment: 11 pages, 5 figure