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21/4 Staraya Basmannaya Ulitsa
email: facultyofphysics@hse.ru
Research
The International Laboratory for Condensed Matter Physics is currently the main research division of the Faculty of Physics (Laboratory Head — Yury Makhlin, Academic Supervisor — Lev Ioffe). The laboratory was established in June 2016 to organize fundamental research in condensed matter physics at HSE University. The laboratory brings together leading Russian physicists from six research centres of the Russian Academy of Sciences, who are also engaged in teaching and research activity at the HSE Faculty of Physics.
Here are several research projects currently being implemented by the faculty staff:
Velocity statistics inside coherent vortices generated by the inverse cascade of 2-D turbulence
Chief Research Fellow at the Laboratory for Condensed Matter Physics, Landau Institute for Theoretical Physics
Chief Research Fellow at the Laboratory for Condensed Matter Physics, Landau Institute for Theoretical Physics
Igor Kolokolov and Vladimir Lebedev, scientific experts from HSE’s Faculty of Physics and the Landau Institute for Theoretical Physics of Russian Academy of Sciences, have developed an analytical theory, which binds the structure of coherent vortices formed due to inverse cascades in 2-D turbulence with the statistical properties of hydrodynamic fluctuations. Uncovering this link can be useful in identifying the causes of the particular characteristics of such atmospheric phenomena as cyclones and anticyclones. Their research is presented in an article published in the ‘Journal of Fluid Mechanics.’
‘This concerns how order comes out of chaos,’ Lebedev said, noting, ‘we were able to generate an analytical scheme, which explains the results of numerical and laboratory experiments where coherent vortices (stable vortex formations) are observed by relating vortex characteristics to the statistical properties of chaotic fluctuations.’
The article ‘Velocity Statistics Inside Coherent Vortices Generated by the Inverse Cascade of 2-D Turbulence,’ published in the Journal of Fluid Mechanics, presents a consistent analytical theory, which describes both the intensive mean flow inside the vortices and the fluctuations therein. Namely, the research indicates that the vortices possess a universal structure, when there is an interval, the azimuth speed does not depend on distance from the vortex centre. Statistical properties of the fluctuations in the universal interval are established. They can be used, for instance, to determine advection and mixing of pollutants in the turbulent flow.
Influence of a thin compressible insoluble liquid film on the eddy currents generated by interacting surface waves
Associate Professor in the Faculty of Physics, Landau Institute for Theoretical Physics
Associate Professor at the Faculty of Physics, Landau Institute for Theoretical Physics
Scientists from the Higher School of Economics and the Landau Institute for Theoretical Physics of the Russian Academy of Sciences have investigated how vortex flows penetrate the interior of a liquid. The authors of the article have shown that specific (thin liquid and insoluble) films on the surface of water enhance eddy currents. These currents are produced by the interacting surface waves directed at an angle to each other. The results of the study have been published in Physical Review Fluids.
Since ancient times, it has been known that films on the surface of a liquid affect its movement. The ancient Greeks once poured oil overboard to calm the ocean. The produced oil film increased vertical vortex flows in a thin layer near the surface, which resulted in the suppression of the amplitude of surface waves.
‘Upon the wave motion, the viscosity of a liquid leads to the formation of vertical vortex flows concentrated in a thin layer near the surface. The film on the surface of a liquid enhances vertical vortices near the surface, which leads to an increase in horizontal eddy currents,’ explains Vladimir Parfenyev.
The authors of the article have established that contributions to horizontal eddy currents, due to Stokes drift and Euler vorticity, depend on depth to different extents. Both terms decay exponentially on a scale of the order of the wavelength, but the Stokes drift decays more rapidly. That is, if you move away from the surface (deeper) to a distance equal to the wavelength, the vortices will not be visible. In addition, the Stokes drift will disappear earlier; this means that the Eulerian vorticity will always dominate at some depth, even if the surface of a liquid is not covered by the film.
Dusty plasmas in the lunar exosphere: Effects of meteoroids
Journal of Physics. Conference Series
Professor in the Faculty of Physics, Russian Space Research Institute
HSE researchers, together with colleagues from Space Research Institute of RAS, MIPT, and the University of Colorado, ventured to discover where the plasma-dust cloud around the Moon comes from. To do so, they compared theoretical calculations with experimental data and theorized that this cloud likely consists of matter that rose from the Moon’s surface as a result of meteoroid collisions. Their paper determines the nature of the dusty plasmas found around the Moon and provides a theoretical foundation for previous observations.
Interplanetary space in the Solar System is filled with dust particles. They are present in planet ionospheres and magnetosphere plasmas, as well as circulate cosmic bodies that lack an atmosphere. Due to high temperatures, the only place where there is no dust is on the Sun and in near proximity to it.
‘During the Surveyor and Apollo space missions to the Moon, it was observed that sunlight scatters at the terminator, which leads to lunar horizon glow and streamers over the surface (despite the Moon’s lack of atmosphere). Most probably, the light scatters on charged dust particles, the source of which is the Moon’s own surface. Indirect proof of the existence of a lunar plasma-dust cloud was also observed during Soviet expeditions, Luna 19 and Luna 22, according to Sergey Popel, one of authors of the research project, Doctor of Science in Physics and Mathematics, Professor at the HSE Faculty of Physics and Head of the Laboratory of Plasma Dust Processes in Space Objects at Space Research Institute of RAS.
The project’s authors looked at the possibility of the lunar plasma-dust cloud’s evolution due to meteoroid collisions with the Moon’s surface. The data received on the basis of this theory generally coincide with the results of experimental studies conducted under the auspices of the American LADEE (Lunar Atmosphere and Dust Environment Explorer) mission.
Cosmic Rays near Proxima Centauri b
Associate Professor at the Faculty of Physics, Russian Space Research Institute
Researchers from the Higher School of Economics and Space Research Institute (Russia) have calculated the main parameters that determine space weather close to the nearest Earth-like exoplanet, Proxima Centauri b. Such parameters include solar wind, as well as galactic and solar cosmic rays. The results of the research were published in Astronomy Letters.
Proxima Centauri b is the closest exoplanet to the Solar System where life might exist. The exoplanet is located in the circumstellar habitable zone of the red dwarf Proxima Centauri, which indicates that the temperature on the surface of Proxima b is suitable for the existence of liquid water.
Over the last two years, considerable research has been done on Proxima b’s potential for life. To determine whether life can survive on the planet, it is not enough to know just the temperature on the planet’s surface; it is also important to study radiation conditions. The cosmic rays that determine these conditions, however, are no longer being discussed practically. Researchers from the Braunschweig University of Technology have looked at the impact of cosmic rays on exoplanets, but their research does not factor in the impact of solar wind. This is the task Russian scientists set out to solve.
In their calculations, the study’s authors used simple models developed to help understand the Sun in the 1950s-1960s, and for the first time ever they determined the radiation conditions near Proxima b.
‘Such simple models were used for one reason – our knowledge of other stars is on par with our knowledge of the Sun in the fifties and sixties. The advantage of these models is that they do not require a large number of input parameters,’ explains HSE Physics Faculty Associate Professor Andrey Sadovski, one of the study’s authors.