scholarly journals Asymptotic expansion of pair production probability in a time-dependent electric field

2015 ◽  
Vol 30 (35) ◽  
pp. 1550210
Author(s):  
Takashi Arai
Keyword(s):  
Asymptotic Expansion ◽  
Electric Field ◽  
Electric Fields ◽  
Quantum Electrodynamics ◽  
Strong Field ◽  
Order Term ◽  
Constant Electric Field ◽  
Particle Creation ◽  
Single Pulse ◽  
Time Interval

We study particle creation in a single pulse of an electric field in scalar quantum electrodynamics. We investigate the parameter condition for the case where the dynamical pair creation and Schwinger mechanism respectively dominate. Then, an asymptotic expansion for the particle distribution in terms of the time interval of the applied electric field is derived. We compare our result with particle creation in a constant electric field with a finite-time interval. These results coincide in an extremely strong field, however they differ in general field strength. We interpret the reason of this difference as a nonperturbative effect of high-frequency photons in external electric fields. Moreover, we find that the next-to-leading-order term in our asymptotic expansion coincides with the derivative expansion of the effective action.

scholarly journals Exactly solvable cases in QED with t-electric potential steps

2017 ◽  
Vol 32 (18) ◽  
pp. 1750105 ◽  
Author(s):  
T. C. Adorno ◽  
S. P. Gavrilov ◽  
D. M. Gitman
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Electric Potential ◽  
Constant Electric Field ◽  
Particle Creation ◽  
External Electromagnetic Field ◽  
Mean Values ◽  
Closed Form Solutions ◽  
Exactly Solvable ◽  
Klein Gordon

In this paper, we present in detail consistent QED (and scalar QED) calculations of particle creation effects in external electromagnetic field that correspond to three most important exactly solvable cases of t-electric potential steps: Sauter-like electric field, T-constant electric field, and exponentially growing and decaying electric fields. In all these cases, we succeeded to obtain new results, such as calculations in the modified configurations of the above-mentioned steps and detailed considerations of new limiting cases in already studied steps. As was recently discovered by us, the information derived from considerations of exactly solvable cases allows one to make some general conclusions about quantum effects in fields for which no closed form solutions of the Dirac (or Klein–Gordon) equation are known. In the present paper, we briefly represent such conclusions about universal behavior of vacuum mean values in slowly varying strong electric fields.

Electronic structure of POPC phospholipids under constant electric field

2017 ◽  
Vol 31 (22) ◽  
pp. 1750157
Author(s):  
Jaciéli Evangelho de Figueiredo ◽  
Leandro Barros da Silva
Keyword(s):  
Electronic Structure ◽  
Dipole Moment ◽  
External Field ◽  
Electric Field ◽  
Electric Fields ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Constant Electric Field ◽  
Ab Initio Study ◽  
Electronic And Structural Properties

We report in the present paper an ab initio study on the electronic and structural properties of phospholipidic membranes under the influence of electric fields. We show that the external field alters the charge distribution of the molecule leading to a modification in the electric dipole moment. The torque on the phospholipid may then cause a transmembranar stress, which by its turn, weakens the membrane allowing to the formation of a pore.

scholarly journals Some features of stepped and dart-stepped leaders near the ground in natural negative cloud-to-ground lightning discharges

2002 ◽  
Vol 20 (6) ◽  
pp. 863-870 ◽  
Author(s):  
X. Qie ◽  
Y. Yu ◽  
C. Guo ◽  
P. Laroche ◽  
G. Zhang ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Broad Band ◽  
Atmospheric Electricity ◽  
Antenna System ◽  
Time Interval ◽  
Return Stroke ◽  
Radio Science ◽  
Lightning Discharges ◽  
Log Normal

Abstract. Characteristics of the electric fields produced by stepped and dart-stepped leaders 200 µs just prior to the return strokes during natural negative cloud-to-ground (CG) lightning discharges have been analyzed by using data from a broad-band slow antenna system with 0.08 µs time resolution in southeastern China. It has been found that the electric field changes between the last stepped leader and the first return stroke could be classified in three categories. The first type is characterized by a small pulse superimposed on the abrupt beginning of the return stroke, and accounts for 42% of all the cases. The second type accounts for 33.3% and is characterized by relatively smooth electric field changes between the last leader pulse and the following return stroke. The third type accounts for 24.7%, and is characterized by small pulses between the last recognizable leader pulse and the following return stroke. On the average, the time interval between the successive leader pulses prior to the first return strokes and subsequent return strokes was 15.8 µs and 9.4 µs, respectively. The distribution of time intervals between successive stepped leader pulses is quite similar to Gaussian distribution while that for dart-stepped leader pulses is more similar to a log-normal distribution. Other discharge features, such as the average time interval between the last leader step and the first return stroke peak, the ratio of the last leader pulse peak to that of the return stroke amplitude are also discussed in the paper.Key words. Meteology and atmospheric dynamics (atmospheric electricity; lightning) – Radio science (electromagnetic noise and interference)

scholarly journals ELECTROPHORESIS IN THE TOTAL (CONSTANT AND ALTERNATING) ELECTRIC FIELD. II. PECULIARITIES OF THE COMBINED IMPACT OF ALTERNATING AND CONSTANT ELECTRIC FIELDS

2020 ◽  
Vol 30 (4) ◽  
pp. 46-51
Author(s):  
B. P. Sharfarets ◽  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Constant Electric Field ◽  
Electrokinetic Phenomena ◽  
Alternating Electric Fields ◽  
Alternating Electric Field ◽  
Electroacoustic Transducer ◽  
Dispersed Medium ◽  
Hydrodynamic Field ◽  
Combined Impact

The hydrodynamics of electrophoresis under the simultaneous impact of constant and alternating electric fields is considered. It has been shown that when the constant and alternating external fields are combined, the energy of the constant electric field is transferred into the alternating hydrodynamic field. An example is given of a dispersed medium in which a giant dispersion of the dielectric constant can arise, which in turn can contribute to an increase in the total electrophoresis rate. Analogies of the behavior of the considered dispersed medium with the action of an electroacoustic transducer based on the use of electrokinetic phenomena are given.

scholarly journals Radiation Problems Accompanying Carrier Production by an Electric Field in the Graphene

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 205
Author(s):  
Sergei P. Gavrilov ◽  
Dmitry M. Gitman ◽  
Vadim V. Dmitriev ◽  
Anatolii D. Panferov ◽  
Stanislav A. Smolyansky
Keyword(s):  
Electromagnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Strong Field ◽  
Numerical Study ◽  
Spectral Composition ◽  
General System ◽  
External Electromagnetic Field ◽  
Quantum Radiation ◽  
Quantized Electromagnetic Field

A number of physical processes that occur in a flat one-dimensional graphene structure under the action of strong time-dependent electric fields are considered. It is assumed that the Dirac model can be applied to the graphene as a subsystem of the general system under consideration, which includes an interaction with quantized electromagnetic field. The Dirac model itself in the external electromagnetic field (in particular, the behavior of charged carriers) is treated nonperturbatively with respect to this field within the framework of strong-field QED with unstable vacuum. This treatment is combined with a kinetic description of the radiation of photons from the electron-hole plasma created from the vacuum under the action of the electric field. An interaction with quantized electromagnetic field is described perturbatively. A significant development of the kinetic equation formalism is presented. A number of specific results are derived in the course of analytical and numerical study of the equations. We believe that some of predicted effects and properties of considered processes may be verified experimentally. Among these effects, it should be noted a characteristic spectral composition anisotropy of the quantum radiation and a possible presence of even harmonics of the external field in the latter radiation.

Strong-field electrophoresis

2012 ◽  
Vol 701 ◽  
pp. 333-351 ◽  
Author(s):  
Ory Schnitzer ◽  
Ehud Yariv
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Double Layer ◽  
Strong Field ◽  
Salt Flux ◽  
Large Reynolds Number ◽  
Diffuse Part ◽  
Electrophoretic Velocity ◽  
Diffusive Boundary ◽  
Diffusive Fluxes

AbstractWe analyse particle electrophoresis in the thin-double-layer limit for asymptotically large applied electric fields. Specifically, we consider fields scaling as ${\delta }^{\ensuremath{-} 1} $, $\delta ~(\ll \hspace *{-2pt}1)$ being the dimensionless Debye thickness. The dominant advection associated with the intense flow mandates a uniform salt concentration in the electro-neutral bulk. The $O({\delta }^{\ensuremath{-} 1} )$ large tangential fields in the diffuse part of the double layer give rise to a novel ‘surface conduction’ mechanism at moderate zeta potentials, where the Dukhin number is vanishingly small. The ensuing $O(1)$ electric current emerging from the double layer modifies the bulk electric field; the comparable $O(1)$ transverse salt flux, on the other hand, is incompatible with the nil diffusive fluxes at the homogeneous bulk. This contradiction is resolved by identifying the emergence of a diffusive boundary layer of $O({\delta }^{1/ 2} )$ thickness, resembling thermal boundary layers at large-Reynolds-number flows. The modified electric field within the bulk gives rise to an irrotational flow, resembling those in moderate-field electrophoresis. At leading order, the particle electrophoretic velocity is provided by Smoluchowski’s formula, describing linear variation with applied field.

scholarly journals Multiphoton intersubband transitions in an armchair graphene nanoribbon

2021 ◽  
Vol 2103 (1) ◽  
pp. 012130
Author(s):  
B S Monozon ◽  
T A Fedorova ◽  
P Schmelcher
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Constant Electric Field ◽  
Graphene Nanoribbon ◽  
Laser Technique ◽  
Strong Light ◽  
Vacuum Decay ◽  
Experimental Values ◽  
Armchair Graphene Nanoribbon ◽  
Armchair Graphene

Abstract We present an analytical approach to the problem of the interband transitions in an armchair graphene nanoribbon (AGNR), exposed to the time-periodic electric field of strong light wave, polarized parallel to the ribbon axis. The two-dimensional Dirac equation for the massless electron subject to the ribbon confinement is employed. In the resonant approximation the probability of the transitions between the valence and conduction size-quantized subbands are calculated in an explicit form. We trace the dependencies of the Rabi frequency for these transitions on the ribbon width and electric field strength for both the multiphoton-assisted and tunneling regimes relevant to the fast oscillating and practically constant electric field, respectively. Estimates of the expected experimental values for the typically employed AGNR and laser technique facilities show that the Rabi oscillations can be observed under laboratory conditions. The data, corresponding to the intersubband tunneling, makes the AGNR a 1D condensed matter analog, in which the quantum electrodynamic vacuum decay can be detected by the employment of the attainable electric fields.

Numerical simulation of the leaky dielectric microdroplet generation in electric fields

2016 ◽  
Vol 27 (01) ◽  
pp. 1650012 ◽  
Author(s):  
Reza Kamali ◽  
Mohammad Karim Dehghan Manshadi
Keyword(s):  
Biological Sciences ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Constant Electric Field ◽  
Fluid Volume ◽  
Dielectric Fluids ◽  
Leaky Dielectric ◽  
Vast Range

Microdroplet generation has a vast range of applications in the chemical, biomedical, and biological sciences. Several devices are applied to produce microdroplets, such as Co-flow, T-junction and Flow-focusing. The important point in the producing process is controlling the separated fluid volume in these devices. On the other hand, a large number of liquids, especially aqueous one, are influenced by electric or magnetic fields. As a consequence, an electric field could be used in order to affect the separated fluid volume. In this study, effects of an electric field on the microdroplet generation in a Co-flow device are investigated numerically. Furthermore, effects of some electrical properties such as permittivity on the separating process of microdroplets are studied. Leaky dielectric and perfect dielectric models are used in this investigation. According to the results, in the microdroplet generating process, leaky dielectric fluids show different behaviors, when an electric field is applied to the device. In other words, in a constant electric field strength, the volume of generated microdroplets can increase or decrease, in comparison with the condition without the electric field. However, for perfect dielectric fluids, droplet volume always decreases with increasing the electric field strength. In order to validate the numerical method of this study, deformation of a leaky dielectric droplet in an electric field is investigated. Results are compared with Taylor theoretical model.

Research Progress on the Electric Coagulation of Fine Dust

2014 ◽  
Vol 955-959 ◽  
pp. 2594-2599
Author(s):  
Ruo Bai Ma ◽  
Kai Quan Wang ◽  
Hai Pu Bi
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Collection Efficiency ◽  
Constant Electric Field ◽  
Research Progress ◽  
Charged Dust ◽  
Fine Dust ◽  
Dust Collection ◽  
Advantages And Disadvantages ◽  
Dust Collection Efficiency

Fine dust in the atmosphere is one of the key factors causing air pollution as well as fog and haze. Due to the limited efficiency of fine dust collection in conventional dust removal technology, pre-charged dust coagulation between particles to increase the effective collecting diameter, is an effective way to improve the dust collection efficiency. Currently, coagulation technology research falls into three mainly aspects: electric coagulation technology in constant electric field, alternating electric field and pulsed electric fields. The advantages and disadvantages as well as the research status and trends are fully analyzed in this paper, of which the technology that uses alternating or pulsed power supply for pre-charge device has more advantages and efficiency in coagulation. They will improve the efficiency of electric coagulation in further on the improved airflow pole with form and structure and the technical development of alternating or pulsed powers, which will make the coagulation and filtration technologies and new composite technology an important development direction of fine dust governance.

scholarly journals Vacuum instability in a constant inhomogeneous electric field: a new example of exact nonperturbative calculations

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
T. C. Adorno ◽  
S. P. Gavrilov ◽  
D. M. Gitman
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Transition Probabilities ◽  
Particle Creation ◽  
Field Configuration ◽  
Quantum Processes ◽  
Reflection And Transmission ◽  
Vacuum Instability ◽  
Klein Gordon

Abstract Basic quantum processes (such as particle creation, reflection, and transmission on the corresponding Klein steps) caused by inverse-square electric fields are calculated. These results represent a new example of exact nonperturbative calculations in the framework of QED. The inverse-square electric field is time-independent, inhomogeneous in the x -direction, and is inversely proportional to x squared. We find exact solutions of the Dirac and Klein–Gordon equations with such a field and construct corresponding in- and out-states. With the help of these states and using the techniques developed in the framework of QED with x-electric potential steps, we calculate characteristics of the vacuum instability, such as differential and total mean numbers of particles created from the vacuum and vacuum-to-vacuum transition probabilities. We study the vacuum instability for two particular backgrounds: for fields widely stretches over the x-axis (small-gradient configuration) and for the fields sharply concentrates near the origin $$x=0$$x=0 (sharp-gradient configuration). We compare exact results with ones calculated numerically. Finally, we consider the electric field configuration, composed by inverse-square fields and by an x-independent electric field between them to study the role of growing and decaying processes in the vacuum instability.

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