Electrical Conductivity Of Plasma Research Articles

Erosion of vanadium in lithium plasma

In this paper the results of first experimental study of the pulse discharges in lithium vapour with vanadium electrodes are presented. The goal of the investigation was modelling the conditions on divertor plates with the lithium protection during current disruptions. The electric current was about 2 ka with pulse duration of several milliseconds. The electron temperature estimated from plasma electrical conductivity was about 2.8 eV. The measured erosion rate of the vanadium anode was about 10 −3 g/C. The dimensions of vanadium droplets scraped out from inner surfaces of the discharge tube have been measured.

Relativistic electron beam propagation in the Earth's atmosphere: Modeling results

Linear accelerators (linacs), capable of producing 5 MeV energy electron beams at 80 mA currents, are now down to a size that allow them to be flown on sounding rockets or balloons. This opens up new opportunities for atmospheric/ionospheric modification experiments where the mesosphere and thermosphere regions of the atmosphere can be perturbed down to 40 km altitude. In this paper beam propagation and atmospheric perturbation effects are studied by Monte Carlo simulations and by analytical means. It is shown that the earth' magnetic field severely limits the radial expansion of the beam otherwise induced by electron‐neutral collisions. It is also shown that the so‐called “envelope‐equations” from high‐energy laboratory physics adequately describe beam propagation in the upper atmosphere. The plasma density and electric conductivity modifications to the atmosphere are calculated from the Monte Carlo simulations. Inside the beam the conductivity in the 40–50 km altitude region is enhanced more than one order of magnitude by a 10 µs‐duration pulse. Some ideas for future scientific investigations are discussed, including the generation of electrical discharges by beams injected over thunderstorm regions.

Utility of Coupling Parameter Γ in Characterizing Electrical Conductivity of Plasmas: Especially Hydrogen and Copper

Abstract Recent experiments of DeSilva and Kunze on the electrical conductivity σ of a copper plasma have been expressed in terms of the plasma coupling parameter Γ = {(ze)2/rs }/kB T. Here rs measures the mean interparticle spacing, while z denotes the (effective) valency. Theoretical results for a structureless hydrogen plasma are presented therefore in a plot of ln σ vs Γ. Since the theory is based on Debye shielding, it is valid for Γ less than 1. Curves of ln σ vs Γ vary with density n for these small values of Γ, but the shapes are very similar for each of the three densities considered. At constant Γ, ln σ vs ln n plots are linear for Γ < 1. Brief comparison with the values of Cu plasma, both experiment and the theory of Likalter for Cu near the metal-insulator transition, is finally made.

Absorption of ultrashort laser pulses by solid targets heated rapidly to temperatures 1-1000 eV.

We report measurements of laser absorption for high-contrast ultrashort pulses on a variety of solid targets over an intensity range of ${10}^{13}$ to ${10}^{18}$ W/ ${\mathrm{cm}}^{2}$. These data give an experimental determination of the target energy content and an indirect measure of dense plasma electrical conductivity. Our calculations accurately reproduce the behavior of aluminum targets, while the other materials show signs of additional absorption mechanisms. At high intensity all target materials reach a ``universal plasma mirror'' state and reflect about 90% of the incident light.

Consideration of crystal structure defectiveness of a powder fuel carbon component in the combustion chamber of a plasma generator

A physicomathematical model and results are presented for numerical studies of gas temperature, plasma electrical conductivity, the Young's modulus of the microflame around aluminum particles, and also the completeness of carbon component combustion for a powder fuel in poly-and monodispersed approximations with movement of a two-phase mixture in a plasma generator combustion chamber. The level of the effect of considering crystal structure defectiveness for carbon particles on the change in these values is established, and it is also shown that under plasma generator conditions of the poly-dispersed model is less sensitive to the model selected for carbon particle combustion.

An axially symmetric finite element model for the electromagnetic behaviour of an RF plasma device

A finite element analysis for the electromagnetic field in an RF plasma system with a quartz confinement tube is presented. The effect of motion and heat on plasma electrical conductivity is taken into account by coupling heat, flow and electromagnetic equations within an iterative method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effect of dispersity of Al and C powders on the electric conductivity of plasma in a pulsed MHD-generator operating on powdered fuel

Effect of dispersity of Al and C powders on the electric conductivity of plasma in a pulsed MHD-generator operating on powdered fuel

Effect of aqueous seed evaporation on combustion temperature and electrical conductivity of MHD plasmas

Transport properties of combustion plasma seeded with an aqueous solution of potassium carbonate are investigated. An atomized seed solution is added to the combustion products of oxygen and liquefied petroleum gas to obtain a weakly ionized plasma at atmospheric pressure. Seed droplets obeying the Nukiyama-Tanasawa distribution are considered to pass through seven stages until eventual evaporation. The electrical conductivity of the plasma has been observed to increase with decreasing mean drop size for a given seeding ratio, especially away from the burner where the seed has completely evaporated. The experimentally measured conductivity is in reasonable agreement with the analytical predictions.

Electrical conductivity and thermodynamic functions of weakly nonideal plasma

The effect of partial screening due to electric microfields within the shielding cloud is examined and used as the basis for determination of electrical conductivity and certain thermodynamic functions of weakly nonideal plasma. A modified screening radius (non-Debye radius) that is greater than the Debye radius is used to take into account short-range Debye–Huckel-type interactions. The evaluation of nonideal plasma electrical conductivity includes corrections to the Spitzer model and accounts for localization of low-energy electrons in the continuum due to incomplete screening. Excellent argeement with experimental results is obtained in the weakly nonideal plasma regime. Corrections to certain thermodynamic functions, such as, chemical potential and internal energy, are evaluated using numerical methods. The effect of charge state on transport coefficients and thermodynamic functions is also analyzed.

Resonance characteristics of a cavity-operated electrodeless high-pressure microwave discharge system

To characterize the resonance behavior of cavity-operated electrodeless high-pressure microwave discharge systems, a microwave circuit is developed that allows high-power network analysis during the operation of the discharge. The frequency-dependent complex impedance of the cavity including the plasma is obtained from a reflection measurement in the range 1.5 GHz-4.5 GHz. This method allows an observation of the actual resonance frequency and the actual vectorial mismatch so that a coupling efficiency >99% can always be achieved with proper adjustment of the operation frequency and coupling probe. Experimental results with a cylindrical TM/sub 010/ cavity and a coaxially situated discharge show a decrease of the resonance frequency with increasing power (increasing plasma temperature, electron density, and electrical conductivity) depending on the discharge geometry and the plasma composition. In accordance with a simple one-dimensional model, the Q factor passes through a minimum at medium power levels, where the cavity discharge system absorbs the microwave energy most effectively. >

状態変数方程式を用いたメタルハライドランプの数式モデル

Recently, miniature HID lamps have been developed and used for the indoor illumination in offices and stores.The ballast for the lamps is required to be smaller size, lighter weight and moreover excellent functions such as dimming, free from the source voltage variation and good controllability. If a dynamic simulation model of the HID lamps is given, it is very useful for the development and design of the such ballasts.In this paper, a simulation model of metal halide lamps is proposed with the state variable equation method based on the electric conductivity of plasma in the bulb. The equations are consist of the state variables such as mercury and halide additive quantity, conductivity of plasma, voltage and current of operating circuit and temperature of the lamp, etc. The calculated results of an 100 W metal halide lamp show comparatively good agreement with the experimental results at the lamp starting and the source voltage variation.

Xenon plasma with caesium as additive

The concentration dependence of xenon plasma with caesium as additive in the temperature region of 2 000 K to 20 000 K has been analysed. Plasma has been considered as weakly nonideal in the complete local thermodynamic equilibrium and the interaction between plasma and vessel walls was not taken into account. The values of some of the parameters for nonideality of plasma with 1% of caesium (γ=0·01010) and 10% of caesium (γ=0·11111) are computed, for initial pressure in plasma ofp0=13 000 Pa and initial temperatureT0=1 000 K. Also the ratio of electrical conductivity of plasma computed by Lorentz's formula and electrical conductivity computed by Spitzer's formula in the same temperature interval has been analysed.

Steady-State Properties of the Fusion Reactor Divertor Plasma

An analytical scope for the steady-state properties of the divertor plasma of the fusion reactor is introduced, namely, the ultimate concentration for He+ and He++ with respect to the divertor effectiveness parameter and impurity diffusion coefficient. Also, the tensorial form for the divertor plasma electrical conductivity in terms of the shielded coulomb multicollision cross sections has been observed to constitute compatible matching for the magneto-fluid interaction phenomenon throughout the divertor channel.

Study of optical properties of dense krypton plasma

Study of the thermophysical properties of dense plasma has heen stimulated by the absence of a strict theory which would adequately describe the thermodynamic, transport, and optical properties of such a medium. A detailed analysis of presently available dense plasma models requires a comparison of their results to experiments performed with various chemical elements. Experimental data on thermodynamic properties and electrical conductivity of dense plasmas of a number of chemical elements shows a general tendency: The experimental enthaply and electrical conductivity of the plasma are lower than the corresponding theoretical values, the differences increasing with increase in charged particle concentration. With regard to optical properties the experimental situation is not well defined. For some elements experimental values have been found to be above theoretical ones, while for other elements the opposite is true. In connection with this further studies of the optical properties of dense plasma over a wide parameter range are necessary.

The Electrical Conductivity of Plasma in Wide Range of Charge Densities

AbstractThe possibility of the existence of plasma oscillations in nonideal plasma and their role in effective “collision” frequency are analyzed. The simple formula for the electrical conductivity of nonideal plasma is obtained on the base of model considerations. An account is taken of a new scattering mechanism, namely, the collective plasma oscillations.

Diagnostics of an rf induction plasma torch with the aid of a magnetic probe

Estimates of a plasma temperature, electrical conductivity, and torch efficiency have been made from simple measurements made on the plasma and on the rf supply. Measurements were made with the aid of a simple magnetic probe and a pickup coil. Estimates are also made of the heating-coil constants.

Some plasma physics experiments on electrical conductivity and similarity laws

Two elementary experiments treating plasma electrical conductivity and similarity laws are described. Plasma is generated by means of commercially available gas tubes. Basic electronic equipment of low cost, available in most laboratories, is used. The experiments are especially suitable for an introductory course in plasma physics.

Propagation of radiation in a plasma situated in a gravitational field

Weak electromagnetic and gravitational fields in a plasma situated in a strong gravitational field, are studied using linearized, general-relativistic, kinetic equations. A tensor operator is constructed for the electrical conductivity of a plasma in a gravitational field, which is a general-relativistic generalization of the electrical conductivity of a homogeneous plasma. Similar tensor operators, which allow one to determine the energy-momentum tensor and the vector current, induced by electromagnetic and gravitational fields in a plasma, are also obtained.

Effect of electric field on non-ideal plasma conductivity

An order of magnitude increase in plasma electrical conductivity with increase in electric field up to 10 3 V/cm has been experimentally observed for plasma with ζ/ Z ≈ 1, where ζ is the number of electrons in Debye sphere, Z = 1–3 is the stage of ionization. The effect vanishes at ζ/Z ≳ 10.

Particle acceleration in planetary magnetospheres

MEASUREMENTS of energetic particle fluxes in space1,2 have stimulated interest in the problem of particle acceleration inside planetary magnetospheres. Suggestions that terrestrial auroral (keV) electron precipitation is associated with transient space charge effects3, have been discarded, largely because the parallel (plasma) electrical conductivity (σ∥) is so large that magnetospheric field lines are constrained to remain equipotentials4.