Formation of singularities on the surface of a liquid metal in a strong electric field

The nonlinear dynamics of the free surface of an ideal conducting liquid in a strong external electric field is studied. It is established that the equations of motion for such a liquid can be solved in the approximation in which the surface deviates from a plane by small angles. This makes it possible to show that on an initially smooth surface for almost any initial conditions points with an infinite curvature corresponding to branch points of the root type can form in a finite time. Zh. éksp. Teor. Fiz. 114, 2043–2054 (December 1998)     

Polaron in a strong alternating electric field

The solution is found for the transport equation for a Feynman polaron having arbitrary coupling interacting with the acoustic oscillations in an alternating electric field. In the low-frequency case, this solution cannot be normalized — there are runaway polarons. For high frequencies, this effect is absent. Equations are obtained for the electrical conductivity of polaron semiconductors for various particular cases, including the runaway regime.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 45–49, April, 1979.     

The effect of strong electric field on lattice relaxation at metal surface

The density functional formalism is used to study changes in the lattice relaxation induced by negative electric field at closed packed faces of Li, Na, Al and Cu. Due to the simple form of the parametrized density profile assumed, the calculation is performed analytically. For the typical fields applied in field emission the calculated relaxations can be increased up to 21% due to the electric field, depending on metal and crystallographic plane considered.     

Nonlinear motion of dielectric microparticles in nematic liquid crystal under strong electric field

Nonlinear electrophoretic motion of spherical dielectricmicroparticles in a cell filled with nematic liquid crystal was experimentally studied for the first time. It was shown that the average microparticle velocity v _EPH depends on the cubic electric field strength E, v _EPH ∼ E ³. It was found that the signal shape of the control electric field has no effect on the functional dependence v _EPH (E ³).     

Stability of a block-copolymer lamella in a strong electric field

Using self-consistent field theory, we examine the stability of a lamellar layer of diblock copolymer subject to strong orthogonal electric fields. Two competing instabilities are identified; one is a peristaltic mode that leads to perpendicular lamellae, and the other is an undulatory mode that results in the formation of an undesirable grain boundary. The former kinetic pathway is favored when the central domain is relatively thin and composed of the low-dielectric material.     

Differential thermopower of a superlattice in a strong electric field

The effect of an electric field on the differential thermopower α(E) of a one-dimensional superlattice is investigated in the semiclassical approximation. A nonmonotonic temperature dependence of α(0) is established for a degenerate electron gas. It is shown that, in principle, an electric field can be used to control the thermoelectric properties of superlattices. Fiz. Tverd. Tela (St. Petersburg) 41, 1314–1316 (July 1999)     

Trap ionization in phosphors in a strong electric field

Temperature dependences of the intensity of Gudden-Pohl flashes in zinc sulfide crystals in various electric fields were measured in order to study trap ionization by electric fields. The decrease in the flash intensity from trap levels of a given depth in a certain temperature range is due to a decrease in the probability for the liberation of an electron from a trap as the temperature decreases. The temperature dependences of the flash intensity found in various electric fields are compared with the theoretical temperature dependence of the probability for electron liberation from a trap. The agreement between experimental and theoretical curves indicates that electrons are liberated from the deeper levels through ionization by an electric field involving many phonons.Translated from Izvestiya VUZ. Fizika, No. 10, pp. 53–58, October, 1969.     

Investigation of a nonequilibrium polariton condensate in cylindrical micropillars in a strong magnetic field

We analyze the photoluminescence of a nonequilibrium polariton condensate in cylindrical micropillars etched on the surface of a high-Q GaAs microcavity in a wide range of detunings in a magnetic field up to 12 T for various levels of nonresonant laser pumping by nanosecond pulses. With such a method of excitation, a considerable effect of the interaction of the reservoir of photoexcited excitons with the condensate on the Zeeman splitting of the polariton condensate levels can be expected, which can lead to a decrease in its value and even to sign reversal. However, the measurements of photoluminescence in a wide range of optical excitation densities show that Zeeman splitting weakly depends on the optical pumping (its variation does not exceed 15% of the splitting in a field of 12 T). The estimation of the exciton density in the reservoir based on these data gives a value lower than 10⁸ cm^–2. In addition, a noticeable decrease (by a factor of about 1.8) in the polariton condensation threshold in a magnetic field is detected.     

Double photoexcitation of helium in a strong dc electric field

We report the first experimental measurements of the effect of an applied field on the photoexcitation and autoionization of doubly excited states of helium. Ground-state photoionization spectra have been measured in the region below the He+(N=2) threshold with static electric fields of up to 84.4 kV/cm across the interaction region. The results are compared to the theoretical calculations of Chung et al. [J. Phys. B 34, 165 (2001)]], which are the only calculations available in this regime. Transitions to several states in the N=2, n=6 manifold are assigned, and a wealth of new structure is observed. Our data show that many more series are mixed in by the field than those predicted by theory.     

Effect of electron exchange on atomic ionization in a strong electric field

Hartree-Fock atom in a strong electric static field is considered. It is demonstrated that exchange between outer and inner electrons, taken into account by the so-called Fock term affects strongly the long-range behavior of the inner electron wave function. As a result, it dramatically increases its probability to be ionized. A simple model is analyzed demonstrating that the decay probability, compared to the case of a local (Har-tree) atomic potential, increases by many orders of magnitude. As a result of such increase, the ratio of inner to outer electrons ionization probability became not too small. It is essential that the effect of exchange upon probability of inner electron ionization by strong electric field is proportional to the square of the number of outer electrons. It signals that in clusters the inner electron ionization by strong field, the very fact of which is manifested by e.g. high energy quanta emission, has to be essentially increased as compared to this process in gaseous atomic objects.     

Phase transformations in quaternionic quantum field theory

Phase transformations of a scalar quaternionic quantum field are examined as unitarily implemented symmetries. Under very general quantization conditions it is shown, in both global and local cases, that the only sensible phase invariance that has been suggested is pp ^–1, wherep is a quaternion and a quaternionic scalar field.     

Electron-positron pair production in a strong asymmetric laser electric field

By solving the quantum Vlasov equation, electron positron pair production in a strong electric field with asymmetric laser pulses has been investigated. We consider three different situations of subcycle, cycle and supercycle laser pulses. It is found that in asymmetric laser pulse field, i.e.. when the pulse length of one rising or falling side is fixed while the pulse length of the other side is changed, the pair production rate and mnnber density can be significantly modified comparable to symmetric situation. For each ca,se of these three different cycle pulses, when one side pulse length is constant and the other side pulse length becomes shorter, i.e., the whole pulse is compressed, the more pairs can be produced than that in tile vice versa case, i.e., the whole pulse is elongated. In compressed pulse case there exists an optimum pulse length ratio of asylnmetric pulse lengths which makes the pair number density maximunn. Moreover, the created maximum pair number density by subcycle pulse is larger than that by cycle or/and supercycle pulse. In elongated pulse case, however, only for supercycle laser pulse the created pairs is enhanced and there exists also an optimum asymmetric pulse length ratio that maximizes the pair number density. On the other hand. surprisingly, in both cases of subcycle and cycle elongated laser pulses, the pair number density is monotonically decreasing as the asymmetry of pulse increases.     

X-ray production by a laser plasma in a strong electric field

The X-ray emission of a laser plasma from metal targets in a 26 kV cm^–1 electric field is investigated experimentally. A substructure of the X-ray pulse, corresponding to the laser pulse train period is found. The spectrum of the radiation in the range 2–25 keV is measured.     

Drift effect on vacuum birefringence in a strong electric and magnetic field

As an important QED effect to detect the vacuum polarization, birefringence in the presence of a strong electric and magnetic field, E0⊥ B0, E0≤ c B0, is considered. The directional dependence of birefringence is obtained. In two special cases: E0= 0 and E0= c B0, our results are consistent with the previous ones. The refractive index of the probe wave propagating in the -E0× B0 direction decreases with E0/c B0, while that in the-E0× B0 direction increases with E0/c B0.The physics of the direction dependence of birefringence maybe the E0× B0 drift velocity of the virtual electrons and positrons.