Ground state energy of current carriers in graphene

The ground state energy of current carriers in graphene considered as a zero-gap semiconductor was calculated in the two-band approximation. The condition of the electronic (hole) system stability in graphene was obtained. The possibility of the zero-gap semiconductor—semimetal transition was discussed.     

Filamentation and stimulated Brillouin scattering in a turbulent plasma

This paper presents a theory of filamentation and stimulated Brillouin scattering (SBS) of high-frequency electromagnetic radiation in a weakly collisional plasma with ion-acoustic turbulence. When the square of the wavelength of the plasma perturbations is less than the product of the two mean free path lengths of an electron with respect to its collisions with turbulent fluctuations and with electrons, the influence of cold highly collisional electrons on the parametric instabilities becomes apparent. It is shown that the plasma turbulence lowers the filamentation threshold, and the SBS threshold can be either lowered or raised. The dependence of the SBS and filamentation thresholds on the electron mean free path length in the turbulent plasma and on the anisotropy of the plasma turbulence is determined. The corresponding dependence of the spatial scale of the most efficiently growing filaments and their spatial growth rate are found. Zh. éksp. Teor. Fiz. 113, 629–645 (February 1998)     

On the superdiffusive scalings of transport in plasma

It is proposed to consider the scalings of anomalous transport (superdiffusion), determined experimentally in turbulent plasma of the Earth’s magnetosphere and laboratory plasma of thermonuclear facilities and processed using modern statistical cascade models of strong turbulence with intermittency, also within the approach of physical kinetics to the theory of plasma turbulence.     

Nonlinear spectral properties of stimulated Brillouin scattering in plasma

New phenomena in which the stimulated Brillouin scattering (SBS) changes the number and magnitude of frequency shifts in a plasma upon a nonlinear increase in the pumping field intensity are discovered. It is found that the SBS becomes forbidden and then allowed again (upon a subsequent increase in the pumping intensity).     

Magnetic field generation in a plasma produced through atomic ionization by circularly polarized radiation

We have established the dependences of the maximum Weibel instability growth rate and the corresponding wavenumber on the degree of anisotropy in the photoelectron distribution formed through tunnel atomic ionization in the field of a circularly polarized short laser pulse. We show how the relaxation of the initial distribution of photoelectrons due to their collisions with ions affects the pattern of generation of a quasi-static magnetic field.     

Cherenkov radiation from an Abrikosov-Josephson vortex

The Cherenkov radiation of generalized Swihart waves is investigated in connection with the slow motion of an Abrikosov-Josephson vortex, which corresponds to a 2 π kink in the phase difference of Cooper pairs on opposite sides of a tunnel junction. The radiative friction force acting on such a vortex is determined. An evaluation is made of the steady-state vortex velocity when the accelerating influence of an electric current through the Josephson junction is compensated by radiative slowing of the vortex due to Cherenkov radiation from the Abrikosov-Josephson vortex. Fiz. Tverd. Tela (St. Petersburg) 39, 444–448 (March 1997)     

Effect of Cherenkov dissipation on vortex velocity in a waveguide-coupled Josephson junction

A motion of slow and fast vortices in a waveguide-coupled Josephson junction induced by a transport current flowing through the entire structure is studied; the coupling is not assumed to be weak. For a fast vortex, conditions are established under which current oscillations due to energy dissipation via Cherenkov radiation of Swihart waves become comparable to the current compensating for ohmic losses in the Josephson junction, waveguide, and adjacent superconductors. For a slow vortex, it is proved that intermediate and strong couplings of the Josephson junction to the waveguide shift current oscillations to the velocity range below the Swihart velocity of the Josephson junction.     

Synthesis of 2,5-disubstituted 1,3,4-oxadiazoles containing a sterically hindered 4-hydroxy-3,5-di(tert-butyl)phenyl group

A series of 2,5-disubstituted 1,3,4-oxadiazoles containing one or two 4-hydroxydi(tert-butyl)phenyl groups has been synthesized. These sterically hindered compounds were prepared by condensation of acids containing the indicated fragment and their derivatives with hydrazine dihydrochloride, hydrazides, and hydrochlorides of iminoesters of acids, by the reaction of 4-hydroxy-3,5-di(tert-butyl)thiphenol with 2-chloromethylsubstituted 1,3,4-oxadiazoles in the presence of KOH, and by cyclodehydration of N-acyl-N-[4-hydroxy-3,5-di(tertbutyl)benzoyl]hydrazones under action of POCl₃.I. M. Gubkin State Oil and Gas Academy, Moscow 117917. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 822–828, June, 1997.