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Small-Scale Magnetic Helicity and Nonlinear Stabilization of the Dynamo
Geomagnetism and Aeronomy. 2017. Vol. 57. No. 7. P. 844–848.
Sokoloff D. D., Yushkov E. V., Lukin A. S.
According to present-day ideas, nonlinear saturation of the astrophysical dynamo and, in particular,
the solar dynamo, are based on the consideration of the magnetic helicity balance, to which the helicities
of the large-scale magnetic field and small-scale field related to it contributed. We show that, in a mirrorasymmetric
medium, the small-scale magnetic field generated by the small-scale dynamo also has a nonzero
magnetic helicity, which also should be taken into account in the magnetic helicity balance.
Keywords: small-scale dynamo
Vergeles S. S., Vointsev I., Physics of Fluids 2026 Vol. 38 P. 024117-1–024117-8
We analytically consider the problem of the Langmuir instability. The instability describes emergence of transverse modulation of horizontal current with vertical shear, when it is superimposed on surface wave co-directional with the flow. Compared to the Craik–Leibovich scheme, we account for the scattering of surface wave on the modulated current, which is significant if the ...
Added: September 26, 2026
Frolov N. Y., Klokov A. Y., Sharkov A. I. et al., Applied Physics Letters 2026 Vol. 128 P. 092201-1–092201-5
Understanding the properties of two-dimensional material interfaces with the substrate is necessary for device applications. Surface acoustic wave propagation through a layered material flake on a substrate could provide unique information on the transverse rigidity of the flake-to-substrate interaction. Ultrasonic waves were generated by a focused femtosecond laser pulse at the surface of a model ...
Added: September 26, 2026
Войтович В. И., Makhov I., Мельниченко И. А. et al., Optics Letters 2026 Vol. 51 No. 17 P. 4872–4875
The influence of cavity surface passivation with SiO2 coating deposited by the plasma-enhanced chemical vapor deposition technique is investigated for injection microdisk lasers with an InGaAsN/GaAs quantum well active region. The electroluminescence spectra of the microdisk lasers with cavity diameters ranging from 12 to 32 μm with and without sidewall surface passivation were studied for a ...
Added: September 25, 2026
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Оптика и спектроскопия 2026 Т. 134 № 3 С. 272–277
Представлены результаты по реализации генерации при повышенных температурах в лазерах с длиной волны генерации 980 nm на основе вертикального микрорезонатора с использованием непоглощающих на длине волны оптической накачки зеркал. Минимальная пороговая мощность накачки составила ~0.8 mW и соответствовала температуре 150 K. Добротность микрорезонатора, определенная на пороге генерации, превысила 13000. Максимальная рабочая температура микролазера составила 195 ...
Added: September 25, 2026
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Письма в Журнал технической физики 2026 Т. 52 № 12 С. 40–43
Реализована одночастотная генерация при 300 K в лазерах на основе вертикального микрорезонатора. Для лазеров с полупроводниковым выводным зеркалом пороговая плотность мощности накачки составила 6.5 kW/cm2. Добротность микрорезонатора и длина волны излучения, определенные на пороге генерации, равнялись 8800 и ~ 959.8 nm. Применение конструкции микрорезонатора с гибридным выводным зеркалом позволило повысить добротность микрорезонатора (до 12 360) ...
Added: September 25, 2026
Бабичев А. В., Makhov I., Kryzhanovskaya N. et al., Письма в Журнал технической физики 2026 Т. 52 № 18 С. 30–34
Представлены результаты реализации генерации при комнатной температуре в планарных вертикальных микрорезонаторах на основе зеркал Al0.2Ga0.8As/Al0.9Ga0.1As. При 300 K пороговая плотность мощности и добротность на пороге генерации составили 11.4± 0.7 kW/cm2 и 5070± 160 соответственно. Двукратное превышение порога генерации привело к увеличению добротности микрорезонатора до 19 000. Эффективный латеральный теплоотвод подтвержден малым сдвигом энергии кванта, который составил ...
Added: September 25, 2026
Budkov Y., Kiselev M. G., Journal of Chemical Physics 2026 Vol. 165 No. 12 Article 124508
We develop a three-mode statistical-mechanical theory for a two-conformer
solute in a near-critical solvent. A compressible lattice model with
vacancies yields the Gaussian free-energy functional for a critical conserved
density, an orthogonal noncritical conserved mode, and the local conformer
fraction. Their couplings follow from packing and cohesive interactions,
rather than being introduced phenomenologically. Kawasaki transport of the
two conserved fields and ...
Added: September 24, 2026
Kryzhanovskaya N., Makhov I., Dragunova A., St. Petersburg Polytechnical University Journal: Physics and Mathematics 2026 Vol. 19 No. 1.1 P. 98–104
The planar microcavity structure was grown using molecular-beam epitaxy.
Single-mode lasing was observed at a wavelength of 960 nm for pillars with a diameter of
15 μm. At 300 K, the lasing threshold was approximately 30 mW. Increasing the pump
power to 2.7 times the threshold power resulted in a mode energy shift of approximately
1 meV. This shift ...
Added: September 23, 2026
Andreeva S., Gavrilov A. A., Dzhikirba K. R. et al., Physical Review B: Condensed Matter and Materials Physics 2026 Vol. 114 Article 134515
We examine plasma excitations with linear dispersion in a system of superconducting electrons in thin
NbN disks. Using frequency-domain terahertz spectroscopy, we study the evolution of plasmons up to critical
temperature Tc. The observed excitations tend to shift to the lower frequencies while temperature is increasing
and the spectral features vanish at T > Tc. We study the ...
Added: September 23, 2026
Образцова А. А., Ivanov K., Moiseev E. et al., Journal of Physics D: Applied Physics 2026 Vol. 59 No. 30 P. 305103
We demonstrate a thermo-optically tunable microlaser based on an InGaAs/GaAs quantum-dot (QD) active region employing a deformed limaçon-shaped cavity. The asymmetric geometry effectively lifts the degeneracy of high-Q whispering-gallery modes, enabling single-mode lasing. A side-mode suppression ratio exceeds 25 dB over a wide current range. Under continuous-wave electrical pumping, the device achieves a peak output power ...
Added: September 23, 2026
Budkov Y., Journal of Chemical Physics 2026 Vol. 165 No. 12 Article 124105
Exact theories of electrolyte structure must satisfy the nonlocal constraints imposed by electrostatic screening, yet these constraints are most commonly formulated only for homogeneous bulk systems and at the level of two-point correlations. Here, we develop a unified field-theoretic framework that extends them to general inhomogeneous ionic fluids and nonlinear charge correlations. Using a standard ...
Added: September 22, 2026
Боровицкая И. В., Пименов В. Н., Коршунов С. Н. et al., Перспективные материалы 2026 № 10 С. 37–54
Проведено сравнение, обобщение и систематизация механизмов эрозии и разрушения
поверхности малоактивируемых материалов, перспективных для использования в
качестве материалов вакуумной камеры термоядерных реакторов: ванадия, его сплава
V – 10 Ti – 6 Cr – 0,05 Zr – 0,1 Si и вольфрама при последовательном воздействии на
них ионных и тепловых потоков. Тепловые потоки имитировали с помощью мощного
импульсного лазерного излучения (ЛИ), создаваемого ...
Added: September 22, 2026
Iontsev M.A., Mukhin S. I., Fistul M. V., Physical Review B: Condensed Matter and Materials Physics 2016 Vol. 94 No. 17 P. 174–510
We report a theoretical study of the ac response of superconducting quantum metamaterials (SQMs), i.e., an array of qubits (two-level systems) embedded in a low-dissipative resonator. By making use of a particular example of a SQM, namely the array of charge qubits capacitively coupled to the resonator, we obtain a second-order phase transition between an ...
Added: September 22, 2026
Shilov A. L., Elesin L., Kravtsov M. et al., Nature Communications 2026 Vol. 17 No. 1 Article 9734
Identifying the microscopic processes limiting conductivity is essential for understanding correlated quantum materials. In twisted bilayer graphene, metallic resistivity follows ρ ~ Tα with widely varying α, fueling competing interpretations from phonon-limited transport and umklapp scattering to strange metallicity and heavy-fermion renormalization. Here, we use terahertz excitation to selectively heat electrons while keeping the lattice cold, separating ...
Added: September 20, 2026
Yushkov E. V., Lukin A., Sokoloff D. D., Journal of Experimental and Theoretical Physics 2020 Vol. 130 No. 6 P. 935–944
We compare the classical mean-field dynamo model proposed by Steenbeck, Krause, and Rädler to describe the generation of large-scale magnetic fields and the Kazantsev model that describes the small-scale dynamo in an unbounded homogeneous and isotropic flow. We consider the subcritical regime of small magnetic Reynolds numbers whereby there is no rapid generation. The same ...
Added: December 2, 2020
Yushkov E. V., Lukin A. S., Geophysical and Astrophysical Fluid Dynamics 2017 Vol. 111 No. 2 P. 138–148
We analyse the asymptotic and numerical solution of the Kazantsev equations for large magnetic Reynolds numbers Rm≫1. For instantaneously correlated random velocity field we obtain the necessary conditions of mirror-asymmetric dynamo processes. We show that simultaneously with longitudinal correlation function, the correlation function for magnetic helicity is also enhanced. We estimate the Rm-threshold for magnetic field generation, ...
Added: January 31, 2020
Yushkov E. V., Lukin A. S., Geophysical and Astrophysical Fluid Dynamics 2017 Vol. 111 No. 6 P. 527–541
Using a magnetic dynamo model, suggested by Kazantsev (J. Exp. Theor. Phys. 1968, vol. 26, p. 1031), we study the small-scale helicity generation in a turbulent electrically conducting fluid. We obtain the asymptotic dependencies of dynamo growth rate and magnetic correlation functions on magnetic Reynolds numbers. Special attention is devoted to the comparison of a longitudinal ...
Added: January 31, 2020
Yushkov E. V., Lukin A. S., Sokoloff D. D., Journal of Experimental and Theoretical Physics 2019 Vol. 128 No. 6 P. 952–958
The possibility of the growth of a small-scale dynamo in a random flow with a weak mirror asymmetry under subcritical generation conditions is investigated. We show that the appearance of an asymmetry in a flow with nonzero helicity leads to the generation of small-scale periodic perturbations. These perturbations, in turn, support active field generation on ...
Added: January 31, 2020
Yushkov E. V., Lukin A. S., Sokoloff D. D. et al., Geophysical and Astrophysical Fluid Dynamics 2019 Vol. 113 No. 1-2 P. 184–198
In this paper, we study the correlation functions for magnetic energy and magnetic helicity generated by a small-scale dynamo mechanism in a mirror-asymmetric and isotropic turbulent conductive fluid. Solving the Kazantsev system for small-scale generation by an iterative approach, we restore the correlation functions in spatial and spectral representations. Studying scales of localisation and their dependence ...
Added: January 31, 2020