Current Distribution of a Cylindrical Antenna in a Warm Plasma

The current distribution of a center-fed dipole cylindrical antenna of arbitrary dimension immersed in unbounded lossless warm plasma is considered, taking into account the commonly neglected end-cap effect. The approximated solution of the integral equation for the current distribution is obtained with the aid of Fourier analysis, and the expression is derived for the current distribution I(z) as the function of position z along the cylindrical surface of the antenna. Sample calculations are made for a half-wavelength dipole antenna with different values of thickness parameter ?=(a/l)<0.25 and of the normalized plasma density parameter po=(?p/?)2 <1. Here a and l denote the radius and the half-length of the antenna, respectively. ?p and ? denote the plasma angular frequency and the radiation angular frequency. The variation of the amplitude and phase of the current with the position, and the variation of radiation resistance with po and ? are examined and discussed in detail.     

Effects of Finite Length Antenna on Cold Plasma Resonance Cone Potential

It is found that the antenna's finite length is sufficient to remove the singularity of the electric potential on the cone without introducing collisions and temperature. This can be understood by recognizing the relationship of the Fourier conjugates ?x ?k ? ? for a spatial wavetrain. The cone amplitude, as well as the cone angle, can be used as a means to diagnose plasma density and magnetic field. A fluid model is used to analyze the case of a linear antenna with gate function charge distribution.     

Influence of an External Electric Field on the Charge and Field Distributions in a Metal Tip

Journal of Experimental and Theoretical Physics - The electric field and charge distributions in a nanosized truncated metal cone in a strong electric field have been found. The geometry of the...     

Resistance and Reactance of Monopole Fields Induced by a Test Charge Drifting Off-Axis in a Cold and Collisional Cylindrical Plasma

We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the electromagnetic field components at all interfaces, the induced monopole electromagnetic fields in the plasma are obtained in the frequency domain. An expression for the plasma electric resistance and reactance is derived and analyzed numerically for some representative parameters. Near the plasma resonant frequency, the plasma resistance evolves with frequency like a parallel RLC resonator with peak resistance at the plasma frequency pe, while the plasma reactance can be capacitive or inductive in nature depending on the frequency under consideration.     

Screening of a Test Charge in Plasma

Nonlinear screening of a test charge in plasma by electrons trapped or untrapped is studied. The obtained results are in rigorous estimations mathematically in comparison with the corresponding Debye screening forms. Meanwhile their validity is physically discussed and some confusions in literature are clarified.     

Radiation from an Electric Dipole Surrounded by a Plasma Cylinder with a Cavity

We solve the problem of the influence of a small-radius (ka1) isotropic plasma cylinder with a coaxial free-space cavity on the radiation from a source of electromagnetic waves to an outer region of free space. Conditions of the resonance radiation are obtained and characteristics of this radiation as functions of the relative size of the cavity are studied. We show that the resonance frequency splits into two frequencies such that the transmission coefficients at these frequencies can exceed the resonance transmission coefficient for the plasma cylinder without a cavity. The results obtained are compared with the case of emission from a two-layer spherical plasma resonator.     

Analysis of Scattering Properties from an Infinite Plasma Cylinder

In this paper, the scattering characteristics of an infinite plasma cylinder are studied theoretically by using the method of eigenfunction expansion. The backscattering cross sections of plasma cylinder in the transverse magnetic (TM) polarization case are calculated in detail. Effects of different parameters on the backscattering cross section are illustrated. Some errors in determining the complex wave number in plasma, as appeared in literatures published previously, are also rectified.     

Charge and current neutralization of an ion-beam pulse propagating in a background plasma along a solenoidal magnetic field

The analytical studies show that the application of a small solenoidal magnetic field can drastically change the self-magnetic and self-electric fields of the beam pulse propagating in a background plasma. Theory predicts that when omega_{ce} approximately omega_{pe}beta_{b}, where omega_{ce} is the electron gyrofrequency, omega_{pe} is the electron plasma frequency, and beta_{b} is the ion-beam velocity relative to the speed of light, there is a sizable enhancement of the self-electric and self-magnetic fields due to the dynamo effect. Furthermore, the combined ion-beam-plasma system acts as a paramagnetic medium; i.e., the solenoidal magnetic field inside the beam pulse is enhanced.     

Current Neutralization and Charge Transport of an REB in Low-Pressure Argon

A numerical study of current neutralization and its effect on charge transport of a 0.175-MeV 6-kA 30-ns relativistic electron beam (REB) in argon at low pressure of 10-2-1 torr is presented. Contribution of two-stream instabilities to plasma conductivity is included in the calculations. The calculations show that energy coupled from beam to plasma is about 1-3 percent in the pressure range 0.1-1 torr. Though the two-stream contribution influences the time-dependent electron temperature and density around 0.1 torr, its effect on beam transport has been found to be only marginal. The results indicate that a maximum charge transport of 76 percent occurs around 0.08 torr when current neutralization is negligible. At 1-torr pressure, 75-percent current neutralization occurs and the charge transport is reduced to 40 percent. The numerical results have been compared with experiment and show good agreement in the pressure range 0.2-1 torr.     

Generation of High Charge State Metal Ions in an Arc Plasma

Russian Physics Journal - Generation of high charge state metal ions in arc plasma is investigated and methods of elevation of the average ion charge state are analyzed. To realize multiple...     

Radiation of the Point Source from an Anisotropic Plasma Cylinder

We obtain and analyze an analytical solution to the problem of electromagnetic-wave radiation of the point electric dipole from an anisotropic plasma cylinder to free space. Two cases of the dipole orientation are considered, where the electric dipole is directed along and across a horizontal magnetic field whose direction does not coincide with the axes of a cylindrical coordinate system. We analyze how the conditions and characteristics of the resonance influence of the anisotropic plasma cylinder depend on the strength of the magnetic field and its direction with respect to the dipole moment of the source. Comparative analysis of the resonance influence of the plasma cylinder with horizontal and axial external magnetic fields is performed.     

Radial Distributions of Dusty Plasma Parameters in a DC Glow Discharge

A non‐stationary non‐local kinetic model for radial distributions of dusty plasma parameters based on the solution of Boltzmann equation for electron energy distribution function is presented. Electrons and ions production in ionizing collisions and their recombination on dust particle surface were taken into account. The drift‐diffusion approximation for ions was used. To obtain the self‐consistent radial distribution of electric potential the Poisson equation was used. It is shown that at high dust particle density the recombination of electrons and ions can exceed their production in ionization collisions in the region of dusty cloud. In this case the non‐monotonous radial distribution of the electric field is formed, the radial electric field becomes reversed and the radial electron and ion fluxes change their direction toward the center of the tube (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Low-Frequency Radiation from an Axisymmetric Current in an Ionospheric Plasma

We consider the radiation of low-frequency electromagnetic waves from an axisymmetric current and propagation of these waves in a homogeneous ionospheric plasma with Hall and Pedersen conductivities. We obtain an analytical expressions for the fields excited by pulsed radial and ring currents. It is shown that electromagnetic radiation propagates as a wave inside a cone along the magnetic field. The field propagation outside the cone is described by a diffusion law. The spatio-temporal characteristics of the signal are determined by the ionospheric conductivities.     

Mass Distributions and Charge Dispersion for the Nuclear Fission

The theory of nuclear fission is reconsidered by introducing the charge asymmetry in the asymmetric two center shell model as a dynamical collective coordinate. The quantum mechanical fluctuations, which are accompanied with the collective motion as a function of the mass asymmetry, are responsible for the mass distributions in nuclear fission. Numerical calculations are carried out for the mass distributions and charge dispersions for the nuclear fission of the ²³⁶U and ²³⁸U nuclei. The present obtained theoretical calculations are in good agreement with the experimental measurements.     

Fe Nanoparticle Production by an Atmospheric Cold Plasma Jet

We present a simple method of producing Fe nanoparticles based on the dissociation of ferrocene by a simple single electrode atmospheric cold argon plasma jet. The system ＆ driven by a sinusoidal ac-supply with a peak voltage of 0-30 k V and a frequency of 50kHz. The average size of iron na~opartieles analyzed by scanning electron microscopy is about 10-30nm for the gas phase samples, and 30-l00nm for the liquid phase samples. The method should be competitive due to its simplicity and low cost.     

Propagation of Ion-Acoustic Wave in an Inhomogeneous Dusty Plasma with. Dust Charge Fluctuation

The propagation of dust ion-acoustic wave in an inhomogeneous dusty plasma is studied by taking the dust charge fluctuation and collisions into account. It is shown that the dust charge fluctuation brings a phase shift to the wave. Furthermore, because of the presence of dust charge fluctuation, a new damping term rises, which makes the damping more sharply.     

Evolution of a Cold Non-neutral Electron-Positron Plasma Slab

Evoiution of a non-neutral cold electron-positron plasma slab is investigated.Initially the slab consists of a quasineutral plasma core bounded on both sides by layers containing only positrons(or electrons).Results from a nonperturbative,or mathematically exact,analysis of the governing fluid conservation equations and the Poisson equation show that despite their equal mass and charge magnitude,the electron and positron fronts can expand separately as well as a single Quid,and that nonlinear surface oscillations can be excited on the expansion fronts.     

Charge Fluctuations in the Two-Dimensional One-Component Plasma

We study, via computer simulations, the fluctuations in the net electric charge in a two-dimensional, one component plasma (OCP) with uniform background charge density –e in a region inside a much larger overall neutral system. Setting e=1, this is the same as the fluctuations in N , the number of mobile particles of charge e. As expected, the distribution of N has, for large , a Gaussian form with a variance which grows only as ^||, where || is the length of the perimeter of . The properties of this system depend only on the coupling parameter =kT, which is the same as the reciprocal temperature in our units. Our simulations show that when the coupling parameter increases, ^() decreases to an asymptotic value ^()^(2)/2 which is equal (or very close) to that obtained for the corresponding variance of particles on a rigid triangular lattice. Thus, for large , the characteristic length _L=2^/ associated with charge fluctuations behaves very differently from that of the Debye length, _D1/ , which it approaches as 0. The pair correlation function of the OCP is also studied.