Interaction of a Charge with the Metal

A rigorous calculation of the thermodynamic equilibrium of the metal–external charge system has shown that the generally accepted assumption that the electric field does not penetrate into the metal is incorrect. In reality, the field penetrates deep into the metal, and the interaction of the charge with the metal is noticeably stronger than the standard interaction with the electric image of the charge. It depends on the characteristics of the electronic system of the metal, on the sign of the charge, and, somewhat differently than the standard one, depends on the magnitude of the charge.     

Self-consistent oscillations of the charge in a waveguide

Small oscillations of the charge in a rectangular waveguide are considered. The electromagnetic field generated by these oscillations and its effect on the charge are investigated. It is found that at a certain frequency there is a self-consistent regime of oscillations wherein the charge oscillates under the influence of its self-field in the absence of external forces. The combination of such a charge and the self-consistent alternating field has the property of a quasiparticle, which is named an electromagneton. Zh. Tekh. Fiz. 67, 120–121 (November 1997)     

On the transistor effect in a vertical structure with a nonconjugated polymer as a transport layer

The charge carrier transport in a multilayer film structure based on a nonconjugated polymer has been studied. The conditions under which the charge carrier transport can be controlled by an electric field due to variations in the potential at the control electrode have been established. The results obtained are discussed within the model of passage of charge particles through a multibarrier system.     

点电荷与介质球系统电势的计算和讨论

计算了点电荷与介质球系统的电势．指出点电荷与导体球、点电荷与无限大导体平面或介质分界平面均匀外电场中有导体球或介质球系统的电势都可由点电荷与介质球系统的电势给出。     

Self-force of a charge in a real current

The analysis of the EM radiation from a single charge shows that the radiated power depends on the retarded acceleration of the charge. Therefore for consistency, an accelerated charge, free from the influence of external forces, should gradually lose its acceleration, until its total energy is radiated. Calculations show that the self force of a charge, which compensates for its radiation, is proportional to the derivative of the acceleration. However, when using this self force in the equation of motion of the charge, one gets a diverging solution, for which the acceleration runs away to infinity. This means that there is an inconsistency in the solution of the single charge problem. However, in the construction of the conserved Maxwell charge density, there is implicitly an integral over the corresponding world line which corresponds to a collection of charged spacetime events. One may therefore consistently think of the “self force” as the force on a charge due to another charge at the retarded position. From this point of view, the energy is evidently conserved and the radiation process appears as an absorbing resistance to the feeding source. The purpose of this work is to learn about the behavior of single charges from the behavior of a real current, corresponding to the set of charges moving on a world line, and to study the analog of the self force of a charge associated with the radiation resistance of a continuum of charges.     

Measurement of the charging of individual dust grains in a plasma

An experiment is described for investigating the charging of dust grains in a plasma. The apparatus is a double plasma device into which single dust grains are dropped from the top. The dust charge is detected and measured by a sensitive electrometer attached to a Faraday cup on the bottom. Experiments with electrons from the emissive filaments but without plasma indicate that the grains charge to approximately the filament potential for filament bias voltages smaller in absolute value than -70 V. The charge is of order 10⁶ electrons for SiC grains 30-150 μm in diameter. At higher bias voltage the charge is reduced due to secondary emission. The charge on grains increases with grain size and is nearly independent of the filament emission current. With plasma in the device, the grains charge both positively and negatively     

Surface density of the polarization charge of a magnetic fluid jet in a uniform electric field

The behavior of magnetic fluid jets in electric and magnetic fields is investigated. A way of calculating the density of a charge forming on the jet’s surface is suggested, and a charge formation mechanism is put forward.     

Point charge in the vicinty of a Kerr black hole

We derive the expression for the electromagnetic field of a point charge at rest on the symmetry axis near a rotating Kerr black hole. This is a generalization of the previously obtained solution for the field of a point charge near a nonrotating Schwarzschild black hole. Unlike the Schwarzschild case the charge is found to give rise to magnetic fields as seen by a stationary or locally nonrotating observer.     

Determination of the charge state distribution of a highly ionized coronal Au plasma

We present the first definitive measurement of the charge state distribution of a highly ionized gold plasma in coronal equilibrium. The experiment utilized the Livermore electron beam ion trap EBIT-II in a novel configuration to create a plasma with a Maxwellian temperature of 2.5 keV. The charge balance in the plasma was inferred from spectral line emission measurements which accounted for charge exchange effects. The measured average ionization state was 46.8+/-0.75. This differs from the predictions of two modeling codes by up to four charge states.     

Analogies between the responses of an oscillator and a dispersive medium to the fields of a moving point charge

It is shown how the essential features of the perturbations created in a dispersive medium by an external charge (namely screening, excitation, and their respective behavior in different velocity ranges), can be seen to have their origin in the ordinary response of one single oscillator to the fields of a moving point charge.     

Manipulation of a single charge in a double quantum dot

We manipulate a single electron in a fully tunable double quantum dot using microwave excitation. Under resonant conditions, microwaves drive transitions between the (1,0) and (0,1) charge states of the double dot. Local quantum point contact charge detectors enable a direct measurement of the photon-induced change in occupancy of the charge states. From charge sensing measurements, we find T1 approximately 16 ns and a lower bound estimate for T*(2) of 400 ps for the charge two-level system.     

Effect of turbulence on the rate of energy loss by a test charge moving in a plasma

The energy loss rate of a charge moving in a turbulent plasma is calculated using the dielectric formalism. It is found that the net effect of the turbulence is to decrease the energy loss rate of the test charge.     

Hard transition radiation produced in a plate and in a stack of plates taking into account the absorbability of the material

A strong, namely quadratic dependence of the total intensity of transition radiation on the Lorentz factor of the charge was shown to appear at sufficiently high charge energies, owing to the specific part the absorbing ability of the material plays in the production of hard transition radiation.     

Role of rotational states in the charge exchange of a dipole-bound anion with a polar molecule

The Landau-Herring method is applied to derive an analytical expression for the exchange interaction potential of a polar molecule with its own dipole-bound anion with account of the relative orientation of the dipole moments of the molecular cores. The potential obtained is used to calculate the cross-section of the resonant charge exchange of a polar molecule with a dipole-bound anion. The influence of the rotation of the molecular cores on the charge exchange cross section is analyzed. A new mechanism of transformation of the charge exchange reaction from quasi-resonant to resonant due to the compensation of the resonance detuning by changes in the rotational states of the colliding molecules is considered.     

Fluctuations of the charge on a dust grain in a plasma

A dust grain in a plasma acquires an electric charge by collecting electron and ion currents. These currents consist of discrete charges, causing the charge to fluctuate around an equilibrium value 〈Q〉. Electrons and ions are collected at random intervals and in a random sequence, with probabilities that depend on the grain's potential. We developed a model for these probabilities and implemented it in a numerical simulation of the collection of individual ions and electrons, yielding a time series Q(t) for the grain's charge. Electron emission from the grain is not included, although it could be added easily to our method. We obtained the power spectrum and the RMS fluctuation level, as well as the distribution function of the charge. Most of the power in the spectrum lies at frequencies much lower than 1/τ, the inverse charging time. The RMS fractional fluctuation level varies as 0.5 |〈N〉|^-1/2, where 〈N〉=〈Q〉/e is the average number of electron charges on the grain. This inverse square-root scaling means that fluctuations are most important for small grains. We also show that very small grains can experience fluctuations to neutral and positive polarities, even in the absence of electron emission     

On the charge of dust particles in a low-pressure gas discharge plasma

Self-consistent molecular-dynamics calculations of the charge of micron-size particles in a low-pressure gas-discharge plasma are performed. It is shown that charge exchange of ions on neutrals starts to affect the charge of dust particles at pressures corresponding to ion mean free paths much greater than the Debye radius. The computational results show that the potential of a particle depends nonmonotonically on the pressure and on the particle size.     

Electric field and the charge distribution on the surface of an insulator in a vacuum

The free charge steady-state distribution over the insulator surface that arises in a strong electric field in a vacuum can be found by solving the boundary-value problem for the electrostatic field strength if the angle between the field vector and vacuum-insulator interface is given. A general solution to this boundary-value problem is derived for the case of an in-plane field and rectilinear interfaces. Laws of charge and field formation that follow from the solution obtained are considered. Formulas for the electric field strength and charge density in terms of elementary functions are obtained for a number of particular cases. Power-type expressions for the electric field and a critical angle between the electrode and insulator surface that describe the field behavior and charge distribution near the vacuum-insulator-electrode contact are derived.     

Formation of the charge and energy distributions of heavy ions in a material in the diffusion model

We investigate the formation of the charge and energy distributions of ions that slow down and randomly change their charges in collisions with particles of the medium. We study the influence that the spread of ions in charge has on the shape of the Bragg curve. The suggested diffusion approximation for the kinetic equation of heavy ions allows the parameters of the ion charge and energy distributions to be easily determined in the entire ion path. The parameters of the ion charge distribution are shown to be related to the ionization-recombination cross sections. The ion distributions calculated in the suggested analytical model are compared with the results of numerical calculations. We have obtained good agreement between the analytical, numerical, and experimental results.     

Electrostatic instability of the lateral surface of a viscous liquid finite-conductivity jet in a collinear electrical field

The influence of the finiteness of the charge transfer rate on the electrostatic instability of the lateral surface of a viscous liquid jet is studied. The study is based on the analysis of a dispersion relation for flexural-deformation capillary waves on the surface of the jet with allowance for charge relaxation. The jet is subjected to a superposition of two electrostatic fields one of which is collinear with the jet’s axis and the other is directed radially to the former. It is found that the finiteness of the potential equalization rate influences jets of a poorly conducting liquid most strongly. The charge relaxation shows up in the appearance of both periodic and aperiodic “purely relaxation” flows. Relaxation flows give rise to electrostatic instability in low-permittivity liquids. When the conductivity of the liquid drops, the instability growth rate of relaxation waves grows and their spectrum expands toward shorter waves. An increase in the charge surface diffusion coefficient introduces destabilization into the relaxation flows of the liquid, which may eventually become unstable.     

Surface states and the charge of a dust particle in a plasma

We investigate electron and ion surface states of a negatively charged dust particle in a gas discharge and identify the charge of the particle with the electron surface density bound in the polarization-induced short-range part of the particle potential. On that scale, ions do not affect the charge. They are trapped in the shallow states of the Coulomb tail of the potential and act only as screening charges. Using orbital-motion limited electron charging fluxes and the particle temperature as an adjustable parameter, we obtain excellent agreement with experimental data.