Birefringence and dielectric relaxation in strong electric fields

In this paper, we present numerical results for steady-state and time-dependent currents as well as for a long-time average current in strong nonlinear dc and ac electric fields for an electron gas in a one-dimensional (1D) quantum-dot superlattice. A microscopic model is employed for the scattering of electrons by phonons and static impurities by means of the Boltzmann equation method. The dc results are favorably compared with recent exact analytic results based on a relaxation-time model for electron-phonon scattering. Our results demonstrate the different roles played by elastic and inelastic scattering on the damped Bloch oscillations as well as the nonlinear steady-state current and their opposite roles on the damped dynamical localization. We also find a suppression of dynamical localization by strong Bloch oscillations and features in the Esaki-Tsu peaks in the presence of an ac electric field when electron scattering is included. On the basis of a nonequilibrium electron distribution obtained from the Boltzmann equation, a self-consistent-field approach is employed to establish a general formalism for the optical response of current-driven electrons in both the linear and nonlinear regimes to a 1D quantum-dot superlattice. The dc-field dependences of both the peak energy and peak strength in the absorption spectrum for a 1D quantum-dot superlattice are calculated, from which we find: (1) both the peak energy and its strength are significantly reduced with increasing dc electric field; and (2) the peak energy and peak strength are anomalously enhanced by raising the temperature for the nonlinear transport of electrons when a strong dc electric field is applied.

Current theories of the nonlinear static and dynamic dielectric susceptibilities of polar fluids subjected to strong AC and DC electric fields are reviewed with specific emphasis on those extending Debye’s theory of linear dielectric relaxation of an assembly of polar molecules. The inclusion of intermolecular interactions in this theory as well as nonlinear dielectric relaxation in the presence of time-dependent fields is discussed. In particular, we emphasize the role played by intermolecular interactions in the determination of the macroscopic dielectric properties of a polar fluid via microscopic calculations, in both the linear and nonlinear responses.

view Abstract Citations (21) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Direct Radiation from a Strong DC Electric Field Wentzel, Donat G. Abstract Simulations have shown that a strong dc electric field yields, after electrostatic transients, a beam of electrons that is nearly flat in velocity distribution yet emits strong electrostatic and electromagnetic waves. Electric energy is converted 'directly' into radiation. This radiation is derived analytically in order to learn how the radiation may depend on field strength and beam density in astronomical objects. Any wave with a significant electric component along the dc electric field grows exponentially in time, with the growth rate proportional to the number of electrons in the beam. The lower limits on the dc electric field and the beam density are set by competing plasma processes. The results are related to solar millisecond radio bursts. Publication: The Astrophysical Journal Pub Date: May 1991 DOI: 10.1086/170049 Bibcode: 1991ApJ...373..285W Keywords: Direct Current; Electric Fields; Plasma Radiation; Solar Flares; Solar Radio Bursts; Analytic Functions; Electromagnetic Radiation; Electron Beams; Electrostatic Waves; Velocity Distribution; Solar Physics; PLASMAS; RADIATION MECHANISMS; SUN: FLARES; SUN: RADIO RADIATION full text sources ADS |

In the Bogolyubov method of reduced description of nonequilibrium states kinetic equation for electron in polar crystal has been obtained in the presence of homogeneous steady strong electric field without assumption about its weakness. A case of weak electron-phonon interaction is studied in detail.

This paper summarizes a long series of experiments that have been done on Rydberg states of Rb. The basic experimental technique that has been used is atomic-beam laser spectroscopy which allows both low-resolution and high-resolution studies. Excitation of Rydberg states is provided by single-photon absorption from a suitably frequency-doubled rhodamine $6G$ tunable laser. Detection is done by field ionization and ion counting. These techniques have allowed us to study the critical ionizing field, which has been found to follow classical, hydrogenic behavior closely. Rydberg states of Rb have been observed from $n=28$ up to $n>100$. High-resolution spectroscopic studies have led to measurement of the fine structure for $\mathrm{np}$ levels located between $n=28$ and $n=60$, as well as the isotope shift of the ground state, $\ensuremath{\delta}\ensuremath{\nu}=(172\ifmmode\pm\else\textpm\fi{}15)$ MHz. Anomalies in the intensity ratio of the doublet $5s\ensuremath{-}np$ transitions have been observed and interpreted as relativistic effects. Perturbations by weak and strong dc electric field are reported. In the case of weak electric fields it is possible to evaluate the polarizability. In the case of strong dc electric fields, new phenomena have been observed and analyzed. We also find experimental evidence of selective photoionization in the presence of an appropriate dc electric field, which could have some applications in laser isotope separation. Finally, we give the preliminary results of an experiment on the effect of a strong nonresonant electromagnetic field on high-lying Rydberg states.

Dipolar interactions in molecules aligned by strong AC electric fields

Stochastic equations of the hydrodynamic theory of plasma are presented in relation to strong external fields. It is shown that the use of these stochastic equations makes it possible to obtain new theoretical solutions for plasma as a result of its heating in a strong external electric field. Theoretical solutions for the conductivity of turbulent plasma when heated in an external electric field of 100 V/cm are considered. Calculated values for the electron drift velocity, electron mobility, electron collision frequency, and the Coulomb logarithm in the region of strong electric fields are obtained. Here we consider experiments on turbulent heating of hydrogen plasma in the range of electric field strength of 100 < E < 1000. The calculated dependences of plasma conductivity are in satisfactory agreement with experimental data for heating plasma in a strong electric field. It is shown that the plasma turbulence in the region of strong electric fields E ~1000 V/cm is close to 100%. For the first time, it is confirmed that the derived dependences for collision frequency, drift velocity, and other values include the degree of turbulence of plasma, which makes it possible to correctly describe experimental data for heating plasma even with strong electric fields. In addition, it was determined that the scatter of experimental data may be associated with the variability of the function in the expression for the heat flux density. For the first time, it is shown theoretically that the experimentally determined fact of the possibility of the existence of an approximate constancy of plasma conductivity in the region E = 100–1000 V/cm can occur with an error of ~30%. The results show significant advantages of the stochastic hydrodynamic plasma theory over other methods that are not yet able to satisfactorily as well as qualitatively and quantitatively predict long-known experimental data while taking into account the degree of turbulence.

Crystals of para-nitroaniline were grown from solution while subjected to a strong dc electric field of 2 X 10<SUP>5</SUP> V/m. This resulted in a modification of the unit cell lattice parameters and space group with respect to crystal grown in the absence of an electric field. The modified crystal are capable of generating a second harmonic signal and poses a significantly lower dielectric permittivity.

Structural control of Ar–HF complexes using dc electric fields: a diffusion quantum Monte Carlo study

The results of a linear analysis for the stability of a homogeneous dielectric liquid with respect to density perturbations in a uniform electric field are presented. The electric field increases the instability increment for the stratification along the field and decreases this increment in the transverse direction. Thus, a strong electric field can induce anisotropic decay into liquid and vapor phases for a fluid that is initially both in a labile state and in a metastable or stable state. Theoretical calculations are confirmed by the results of numerical modeling of the fluid dynamics. The new regions of a low-density phase have the form of narrow cylindrical channels oriented along the field. This new mechanism of gas phase formation in strong local electric fields probably plays a key role in the inception and ultra-fast propagation of streamers during the breakdown in dielectric liquids in a nanosecond range.

Chapter 11 - Nonlinear optics and photonics applications of two-dimensional materials

We give the general results for spontaneous and photon-induced pair production in strong, constant parallel electric and magnetic fields. For photons propagating exactly parallel to the constant fields there is no effect. For photons propagating at right angles to the constant fields the vacuum behaves in a birefringent manner. These results generalize earlier work in the field by others who did not include a constant electric field. Some numerical estimates are given for both the spontaneous and photon-induced pair production rates using numbers currently thought to obtain near the surface of a pulsar-which is believed to possess not only a strong magnetic field but also a strong electric field.

Computer simulations of electrons accelerated by a strong DC electric field show not only very efficient generation of beam waves but also emission of o-mode radiation. We present a set of particle simulations for which we study the behavior of wave generation under varying conditions. We determine that the o-mode arises from a combination of beam waves and of z-mode waves that are themselves generated by beam waves. We estimate how these interactions depend on beam density

With the development of digital twin technology, in the traditional live operation mode of ±800 kV UHVDC transmission lines, the safety protection of live operators has a new form. In this paper, based on the wireless positioning device in live operation of UHVDC transmission, the research on equipment safety under strong DC electric field is carried out. A finite element simulation model is established, and the electric field intensity distribution of the positioning device with and without shielding material protection is calculated and compared. Without the protection of shielding material, the electric field strength of the device is relatively high. After the shielding material is used, the electric field strength of each part of the device decreases to varying degrees. It is verified that in actual production, combined with the protection of suitable insulating material shells and shielding materials, it is practical to use the wireless positioning device to carry out real-time safety positioning protection for live operation of ±800 kV UHVDC transmission lines.

Comparisons of electron and proton distribution functions are made with dc electric field measurements as the S3‐3 satellite crossed a series of high‐latitude acceleration regions near local dusk on July 29, 1976. Potential drops, from parallel electric fields, are inferred from charged particle distributions using adiabatic theory and compared with potentials calculated from measured perpendicular electric fields. There exists a one to one spatial relationship between strong dc electric field enhancements in the form of electric field reversals and acceleration signatures of auroral particles. From the charged particle and electric field analysis, we conclude that electric fields, parallel to B, can extend above and below the satellite altitude near 7500 km when strong electrostatic field reversals are encountered. Within the uncertainties of our analysis, the potential drop below the satellite is comparable to the potential calculated from the individual electrostatic structures crossed by the satellite. There are, in addition, particle signatures that imply a source of strong acceleration was located above and relatively close to the satellite. These accelerated electrons are coincident with auroral hiss and ion conics. In addition to regions of acceleration that extended only fractions of a degree in latitude, there was a broad ‘inverted V structure’ near the polar cap boundary where strong perpendicular electric fields were embedded, giving rise to large variations in the inferred potential below the satellite.