Charged Wire Research Articles

An electric dipolar screen with oppositely polarized insulators for excluding whiteflies from greenhouses

A new electrostatic insect-proof screen (electric dipolar screen) was developed using insulated conductor wire. Copper conductor wire is encased in a flexible transparent vinyl insulator sleeve and charged with an electrostatic voltage generator. Paired insulated conductor wires were placed in parallel with 5 mm of separation and oppositely charged with 15 kV DC using separate electrostatic voltage generators. A negatively charged conductor wire polarizes the insulator negatively at the outer surface and positively on the conductor side, and a positively charged conductor wire polarizes vice versa. A pair of insulated conductor wires with opposite surface charges was used as an electric dipole. An electric dipole creates an electrostatic force from positive to negative poles. This force was harnessed to trap whiteflies entering greenhouses. Dipolar wires were attached in parallel to a frame to construct an electric dipolar screen that could be fitted to greenhouse windows. The screen prevented adult whiteflies from passing through spaces (up to 30 mm) between the wires of the screen, and tomato plants inside remained free of whiteflies throughout the entire 3-week experiment, in contrast to heavy infestation of all plants in the uncharged area. Thus, the electric dipolar screen is a promising tool to physically exclude flying whiteflies from greenhouses.

Beam splitter for guided polar molecules with a Y-shaped charged wire

We propose a beam splitter for cold polar molecules in weak-field-seeking states that uses a Y-shaped charged wire half embedded in a substrate and sandwiched by a charged metallic parallel-plate capacitor. We demonstrate our molecular-beam splitter and study its dynamic beam-splitting process for the guided cold molecules by using Monte Carlo simulation. Our study shows that cold polar molecules from a supersonic beam source with a mean velocity of a few hundred meters per second can be split with a fixed 0.5/0.5 splitting ratio, and an adjustable splitting ratio of about 0.03-0.97 can be realized by introducing a small alteration to the scheme.

Electrostatic Surface Trap for Cold Polar Molecules with aCharged Circular Wire

We propose a novel scheme to trap cold polar molecules on thesurface of an insulating substrate (i.e. a chip) by using aninhomogeneous electrostatic field, which is generated by thecombination of a circular charged wire (a ring electrode) and agrounded metal plate. The spatial distributions of the electrostaticfield from the above charged wire layout and its Stark potentials forCO molecules are calculated. Our study shows that when the voltageapplied to the wire is U = 15 kV, a ring radius is R = 5 mm, thethickness of the insulating substrate is b = 5 mm, and a wire radiusis r = 1 mm, the maximum efficient trapping potential (i.e., asequivalent temperature) for CO molecules is greater than 141.7 mK,which is high enough to trap cold polar molecules with a temperature of50 mK in the low-field-seeking states.

Experimental Study on Electrostatic Guiding of SupersonicD2O Molecular Beam with Two Charged Wires

We demonstrate the guiding of a supersonic heavy-water (D2O)molecular beam using a hollow electrostatic field generated by thecombination of two parallel charged-wires and two groundedmetal-plates, and report some new and preliminary experimentalresults. In the experiment, we detect the guiding signals byusing the method of time-of-flight mass spectrum and study thedependence of the relative transmission of the beam guide on theguiding voltage. Our study shows that the relative transmission of thebeam guide is increased linearly with increasing guiding voltage Vguid, and the number of the guided D2O molecules is atleast increased by 89.4% when the guiding voltage is +20.0 kV. Finally,some potential applications of our guiding scheme in the moleculeoptics are briefly discussed.

Simulation study of solar wind push on a charged wire: basis of solar wind electric sail propulsion

Abstract. One possibility for propellantless propulsion in space is to use the momentum flux of the solar wind. A way to set up a solar wind sail is to have a set of thin long wires which are kept at high positive potential by an onboard electron gun so that the wires repel and deflect incident solar wind protons. The efficiency of this so-called electric sail depends on how large force a given solar wind exerts on a wire segment and how large electron current the wire segment draws from the solar wind plasma when kept at a given potential. We use 1-D and 2-D electrostatic plasma simulations to calculate the force and present a semitheoretical formula which captures the simulation results. We find that under average solar wind conditions at 1 AU the force per unit length is (5±1×10−8 N/m for 15 kV potential and that the electron current is accurately given by the well-known orbital motion limited (OML) theory cylindrical Langmuir probe formula. Although the force may appear small, an analysis shows that because of the very low weight of a thin wire per unit length, quite high final speeds (over 50 km/s) could be achieved by an electric sailing spacecraft using today's flight-proved components. It is possible that artificial electron heating of the plasma in the interaction region could increase the propulsive effect even further.

Electrostatic surface guiding of cold polar molecules with a single charged wire

This paper proposes a scheme to guide cold polar molecules by using a single charged wire half embanked in an insulating substrate and a homogeneous bias electric field, which is generated by a plate capacitor composed of two infinite parallel metal plates. The spatial distributions of the electrostatic field produced by the combination of the charged wire and the plate capacitor and the corresponding Stark potentials (including dipole forces) for metastable CO molecules are calculated, the relationships between the electric field and the parameters of our charged-wire layout are analysed. It also studies the influences of the insulator on the electric field distribution and the discharge effect. This study shows that the proposed scheme can be used to guide cold polar molecules in the weak-field – seeking states, and to form various molecule-optical elements, such as molecular funnel, molecular beam-splitters and molecule interferometer, even to construct a variety of integrated molecule-optical elements and their molecule chips.

Electromagnetic models of the lightning return stroke

Lightning return‐stroke models are needed for specifying the source in studying the production of transient optical emission (elves) in the lower ionosphere, the energetic radiation from lightning, and characterization of the Earth's electromagnetic environment, as well as studying lightning interaction with various objects and systems. Reviewed here are models based on Maxwell's equations and referred to as electromagnetic models. These models are relatively new and most rigorous of all models suitable for computing lightning electromagnetic fields. Maxwell's equations are numerically solved to yield the distribution of current along the lightning channel. Different numerical techniques, including the method of moments (MoM) and the finite difference time domain (FDTD) method, are employed. In order to achieve a desirable current‐wave propagation speed (lower than the speed of light in air), the channel‐representing wire is embedded in a dielectric (other than air) or loaded by additional distributed series inductance. Capacitive loading has been also suggested. The artificial dielectric medium is used only for finding the distribution of current along the lightning channel, after which the channel is allowed to radiate in air. Resistive loading is used to control current attenuation with height. In contrast with distributed circuit and so‐called engineering models, electromagnetic return‐stroke models allow a self‐consistent full‐wave solution for both lightning‐current distribution and resultant electromagnetic fields. In this review, we discuss advantages and disadvantages of four return‐stroke channel representations: a perfectly conducting/resistive wire in air, a wire embedded in a dielectric (other than air), a wire in air loaded by additional distributed series inductance, and a wire in air having additional distributed shunt capacitance. Further, we describe and compare different methods of excitation used in electromagnetic return‐stroke models: closing a charged vertical wire at its bottom with a specified grounded circuit, a delta‐gap electric field source, and a lumped current source. Finally, we review and compare representative numerical techniques used in electromagnetic modeling of the lightning return stroke: MoMs in the time and frequency domains and the FDTD method. We additionally consider the so‐called hybrid model of the lightning return stroke that employs a combination of electromagnetic and circuit theories and compare this model to electromagnetic models.

LORENTZ-SYMMETRY VIOLATION AND ELECTRICALLY CHARGED VORTICES IN THE PLANAR REGIME

We start from a Lorentz noninvariant Abelian-Higgs model in 1+3 dimensions, and carry out its dimensional reduction to D = 1+2. The planar model resulting thereof is composed by a Maxwell—Chern—Simons–Proca gauge sector, a massive scalar sector, and a mixing term (involving the fixed background, vμ) that realizes Lorentz violation for the reduced model. Vortex-type solutions of the planar model are investigated, revealing charged vortex configurations that recover the usual Nielsen–Olesen configuration in the asymptotic regime. The Aharonov–Casher Effect in layered superconductors, that shows interference of neutral particles with a magnetic moment moving around a line charge, is also studied. Our charged vortex solutions exhibit a screened electric field that induces the same phase shift as the one caused by the charged wire.

Equilibrium correlations in charged fluids coupled to the radiation field

We provide an exact microscopic statistical treatment of particle and field correlations in a system of quantum charges in equilibrium with a classical radiation field. Using the Feynman-Kac-Itô representation of the Gibbs weight, the system of particles is mapped onto a collection of random charged wires. The field degrees of freedom can be integrated out, providing an effective pairwise magnetic potential. We then calculate the contribution of the transverse field coupling to the large-distance particle correlations. The asymptotics of the field correlations in the plasma are also exactly determined.

Measurement of Corona Wind Velocity and Calculation of Energy Conversion Efficiency for Air-Side Heat Transfer Enhancement in Compact Heat Exchangers

Corona discharge utilizes the effect of electrically induced secondary motions to enhance the air-side heat transfer coefficients between high-density fins in a fin structure. The objective of this study was to measure the velocity associated with the air jet generated by corona discharge for parametric ranges of interest to air-side heat transfer enhancement in compact heat exchangers. This is the first study of its kind where the nonintrusive laser Doppler velocimetry (LDV) technique was used to measure the velocity, with careful attention paid to correction for the electric field effects on the particles and the resulting slip velocity. Experiments were conducted with a prototypical wire-to-plate geometry (positively charged wire and grounded plate). In two series of experiments, the flow was seeded with 2.5 μm glass microspheres and 0.5 μm polystyrene nanospheres. The corrected velocity measurements were used to calculate the kinetic energy flux to the fluid and the resulting efficiency of the electric-to-kinetic energy conversion.

Relaxation to Boltzmann equilibrium of 2D Coulomb oscillators

We propose a two-dimensional model of charged particles moving along the z -axis, on which they are focused by a linear attracting field. The particles are organized into parallel uniformly charged wires which interact with a logarithmic potential. The mean field is described by the Poisson–Vlasov equation, whereas Hamilton's equations need to be solved to take into account the effect of collisions. The relaxation to the self-consistent Maxwell–Boltzmann distribution is observed in numerical simulations for any initial distribution and the relaxation time scales linearly with the number N of wires, having fixed the total current. We prove that such scaling holds in the kinetic approach given by Landau's theory. To this end, we use an approximation to the cross section of the cutoff logarithmic potential, which is asymptotically exact for large N. The drift term inherits the scaling law of the cross section and provides the required scaling for the relaxation time.

A Novel Electrostatic Guiding Scheme for Cold Polar Moleculesin Weak-Field-Seeking States

We propose a novel electrostatic guiding scheme for cold polarmolecules in weak-field-seeking states using a single charged wire halfembanked in a ceramic substrate (i.e., a chip) and a homogeneous biaselectric field, which is produced by a capacitor composed of two largeparallel metal plates. We calculate the spatial distribution of theelectrostatic fields generated by the combination of the charged wireand the plate capacitor and the corresponding trapping potentials forCO molecules, and analyse the relationships between the electric fieldand the parameters of the charged-wire layout. Our study shows that theproposed scheme with a single charged-wire can be used to guide coldpolar molecules in the weak-field-seeking states, and has somepotential applications in construction of various molecule-opticalelements.

Electrostatic guiding of cold polar molecules on a chip

We propose a novel scheme to guide cold polar molecules on the surface of an insulating substrate (i.e. a chip) using an electrostatic field generated by the combination of a pair of parallel charged wires and a grounded metal plate. The spatial distributions of the electric fields from the above charged-wire layout and their Stark potentials for cold CO molecules and dipole forces are calculated, and the relationships between the electric field and the geometric parameters of our charged-wire system are analyzed. Our study shows that our charged-wire scheme can be used to guide cold polar molecules in the weak-field-seeking state, and to construct various molecular optical elements, such as a molecular funnel, a molecular beam splitter and a molecular interferometer and so on, to form various integrated molecular optical elements and their molecular chips, and even to generate a continuous wave (CW) cold molecular beam by using a low-pass energy filter based on bent two-wire guiding.

Separation of Fullerene and Endofullerene Molecules in Inhomogeneous Electric Field

The present study makes use of the neutral molecule motion model in the inhomogeneous static electric fields. We show the possibility of separating molecules with high polarizability and/or a permanent electric dipole moment in these fields. On the simple example of the electric field of the system of charged parallel metallic wires we have estimated the angle dispersion of the endofullerene molecules Gd@C82, La@C82, Sc@C82, and Y@C82 from the known values of the permanent dipole moments.

Pions versus magnons: from QCD to antiferromagnets and quantum Hall ferromagnets

The low-energy dynamics of pions and magnons—the Goldstone bosons of the strong interactions and of magnetism—are analogous in many ways. The electroweak interactions of pions result from gauging an SU(2) L ⊗ U(1) Y symmetry which then breaks to the U(1) em gauge symmetry of electromagnetism. The electromagnetic interactions of magnons arise from gauging not only U(1) em but also the SU(2) s spin rotational symmetry, with the electromagnetic fields E → and B → appearing as non-Abelian vector potentials. Pions couple to electromagnetism through a Goldstone–Wilczek current that represents the baryon number of Skyrmions and gives rise to the decay π 0→ γγ. Similarly, magnons may couple to an analogue of the Goldstone–Wilczek current for baby-Skyrmions which induces a magnon–two-photon vertex. The corresponding analogue of photon–axion conversion is photon–magnon conversion in an external magnetic field. The baryon number violating decay of Skyrmions can be catalyzed by a magnetic monopole via the Callan–Rubakov effect. Similarly, baby-Skyrmion decay can be catalyzed by a charged wire. For more than two flavors, the Wess–Zumino–Witten term enters the low-energy pion theory with a quantized prefactor N c —the number of quark colors. The magnon analogue of this prefactor is the anyon statistics angle θ which need not be quantized.

Nonlinear electron solutions and their characteristics at infinity

AbstractThe Maxwell-Dirac equations model an electron in an electromagnetic field. The two equations are coupled via the Dirac current which acts as a source in the Maxwell equation, resulting in a nonlinear system of partial differential equations (PDE's). Well-behaved solutions, within reasonable Sobolev spaces, have been shown to exist globally as recently as 1997 [12]. Exact solutions have not been found—except in some simple cases.We have shown analytically in [6, 18] that any spherical solution surrounds a Coulomb field and any cylindrical solution surrounds a central charged wire; and in [3] and [19] that in any stationary case, the surrounding electron field must be equal and opposite to the central (external) field. Here we extend the numerical solutions in [6] to a family of orbits all of which are well-behaved numerical solutions satisfying the analytic results in [6] and [11]. These solutions die off exponentially with increasing distance from the central axis of symmetry. The results in [18] can be extended in the same way. A third case is included, with dependence on z only yielding a related fourth-order ordinary differential equation (ODE) [3].

Neutral atom and a charged wire: From elastic scattering to absorption

We solve the problem of a neutral atom interacting with a charged wire, giving rise to an attractive 1/r^2 potential in two dimensions. We show how a suitable average over all possible self-adjoint extensions of the radial Schroedinger Hamiltonian eventually leads to the classical formula for absorption of the atom, a formula shown to be in agreement with a recent experiment.

Detection of positive and negative ions in a wire ionization counter filled with atmospheric air

The physical processes occurring during the detection of individual ions in a wire counter filled with atmospheric air are studied, and the amplitude distribution of electric pulses is measured. It is shown that a positive ion is detected due to electron emission from the surface of a negatively charged wire, whereas a negative ion is detected due to electron detachment near a positively charged wire. The secondary processes accompanying the neutralization of positive ions at a negatively charged external electrode and negatively charged wire are considered. It is established that, in contrast to standard proportional counters, these secondary processes result in an increase in the number of electric pulses rather than in an increase in the electric pulse amplitude. The wire counter allows the detection of both ions produced inside the detector and ions injected into the detector from the ambient air. Possible applications of air-filled wire detectors are described.

Detection of positive ions in an air cylindrical detector with a negatively charged wire

A new method for detecting positive ions in ambient air was developed. A cylindrical ionization detector with a negatively charged wire, operating in the limited gas amplification mode, was used. The distributions of electric-pulse heights due to positive ions were measured at various voltages between the electrodes. The physical processes inside the detector were studied. The method was used to measure the positive-ion concentration in ambient air. The experimental model of the instrument made it possible to determine the concentrations of positive ions with 1–10−3-cm2/(V·s) mobilities in a range of 102–104 cm−3. Other possible applications of the single-ion detection technique were considered.

Characterization of a Hadamard transform time-of-flight mass spectrometer

A pseudorandom time-of-flight method (also called the cross-correlation method) has been used to perform time-of-flight mass spectrometry with a duty cycle of 50%. Modulation of an ion beam is accomplished by deflecting the ion beam with an interleaved comb of oppositely charged elements. Maximum-length pseudorandom sequences based on Hadamard-type difference sets are produced by feedback shift register circuitry and used for ion beam modulation. The inverse transformation of the recorded signal is carried out speedily with the help of the fast Hadamard transform, which allows real-time monitoring of the mass spectrum. The components of the instrument are described, and its performance is characterized. Trajectory simulations are found to be in good agreement with experimental findings, which aids in understanding the modulation dynamics. It is found that the wire comb modulator can be modeled as a set of ideal deflection plates of length 0.875 l, where l is the spacing between oppositely charged wires.