Resonance microwave volume plasma source

A conceptual design of a microwave gas-discharge plasma source is described. The possibility is considered of creating conditions under which microwave energy in the plasma resonance region would be efficiently converted into the energy of thermal and accelerated (fast) electrons. Results are presented from interferometric and probe measurements of the plasma density in a coaxial microwave plasmatron, as well as the data from probe measurements of the plasma potential and electron temperature. The dynamics of plasma radiation was recorded using a streak camera and a collimated photomultiplier. The experimental results indicate that, at relatively low pressures of the working gas, the nonlinear interaction between the microwave field and the inhomogeneous plasma in the resonance region of the plasmatron substantially affects the parameters of the ionized gas in the reactor volume.     

Structure of a discharge induced by a coaxial microwave plasmatron with a gas-supply channel in the inner electrode

The structure of a discharge induced by a coaxial microwave plasmatron with a gas-supply channel in the inner electrode of a coaxial waveguide is investigated. A plasmatron with a power of up to 10 W operates at a frequency of 10 GHz. Depending on the operation regime, the discharge takes either a filament or torch form. A plasma filament arises at low flow rates of the working gas (argon) and occurs at the border of the potential core of the gas jet. A torch discharge occurs at high flow rates and has the form of a hollow cone. In both cases, the discharge arises in the potential core of the gas jet and does not spread beyond it. The distribution of the microwave field in the discharge plasma is determined.     

Microwave torch as a plasmachemical generator of nitric oxides

The possibility of using a microwave coaxial plasmatron (a microwave torch) as an efficient plasmachemical generator of nitric oxides in an air jet has been studied experimentally. A plasmachemical model of the generator is developed. Results of calculations by this model do not contradict experimental results. A conclusion about the mechanisms governing NO_x production in a plasma torch is drawn by comparing the experimental and calculated results.     

Conversion of methane in a coaxial microwave torch

A microwave coaxial plasmatron (microwave torch) is used as a plasmachemical converter of methane into hydrogen and hydrocarbons. The measured energy cost of methane decomposition is close to its minimum theoretical value. Such a low energy cost is unsurpassed for reactors operating at atmospheric pressure. A model of the plasmachemical converter is constructed. The results of calculations in the frame-work of this model agree well with experimental data.     

Measurements of the temperature of subsonic CO<Subscript>2</Subscript> induction plasma flows by analyzing their emission spectra

Results are presented from measurements of the temperature characteristics of subsonic CO² plasma flows generated by a 100-kW induction plasmatron at the Institute for Problems of Mechanics, Russian Academy of Sciences. The atomic excitation temperature T _a and the population temperature T _e of the electronic states of C2 molecules (both averaged over the jet diameter) were measured from the absolute intensities of the atomic spectral lines and the spectrum of C2 molecules in different generation regimes at gas pressures of 25–140 hPa and anode supply powers of 29–72 kW. The longitudinal and radial profiles of the temperatures were determined for some of these regimes and compared to those obtained from numerical calculations of equilibrium induction plasma flows in the discharge channel. For some generation regimes, the dependences of the averaged (over the line of sight) rotational and vibrational temperatures (T _r and T _v) on the discharge parameters, as well as the radial profiles of these temperatures, were determined from the best fit of the measured and calculated spectra of C₂ molecules (Swan bands). The self-absorption of molecular emission was observed at sufficiently high temperatures and gas pressures, and its influence on the measured values of the molecular temperatures T _e, T _v, and T _r was examined.     

Effect of CoCl2 treatment on major and trace elements metabolism and protein concentration in mice

Cobalt (Co) is a transition metal and an essential trace element, required for vitamin B₁₂ biosynthesis, enzyme activation and other biological processes, but toxic in high concentrations. There is lack of data for the effect of long-term Co(II) treatment on the concentrations of other trace elements. We estimate the influence of cobalt chloride (CoCl₂) on the relative content of different metals in mouse plasma using two-jet arc plasmatron atomic emission and on the total protein content. On average, the content of different elements in the plasma of 2-month-old balb/c mice (control group) decreased in the order: Ca > Mg > Si > Fe > Zn > Cu ≥ Al ≥ B. The treatment of mice for 60 days with CoCl₂ (daily dose 125 mg/kg) did not appreciably change the relative content of Ca, Cu, and Zn, while a 2.4-fold statistically significant decrease in the content of B and significant increase in the content of Mg (1.4-fold), Al and Fe (2.0-fold) and Si (3.2-fold) was found. A detectable amount of Mo was observed only for two control mice, while the plasma of 9 out of 16 mice of the treated group contained this metal. The administration of Co made its concentration detectable in the plasma of all mice of the treated group, but the relative content varied significantly. The treatment led to a 2.2-fold decrease in the concentration of the total plasma protein. Chronic exposure to CoCl₂ affects homeostasis as well as the concentrations and metabolism of other essential elements, probably due to competition of Co ions for similar binding sites within cells, altered signal transduction and protein biosynthesis. Long-term treatment also leads to significant weight changes and reduces the total protein concentration.The data may be useful for an understanding of Co toxicity, its effect on the concentration of other metal ions and different physiological processes.     

Plasma parameters controlled by remote electron shower in a double plasma device

The principal feature of this experiment is the electron showers consisting of three tungsten wires embedded by the plasma, which are heated up consequently emitting electrons inside the diffused plasma to control the plasma parameters in the discharge section of a double plasma device. These cold electrons emitted by the heated filament are free from maintenance of discharge which is sustained in the source section. The target plasma, where electrons are injected is produced as a result of diffusion from the source section. It is found that, plasma density and plasma potential can be effectively controlled in this way.     

Circadian rhythm of plasma sodium is disrupted in spontaneously hypertensive rats fed a high-NaCl diet

High-NaCl diets elevate arterial pressure in NaCl-sensitive individuals, and increases in plasma sodium may trigger this effect. The present study tests the hypotheses that 1) plasma sodium displays a circadian rhythm in rats, 2) the plasma sodium rhythm is disturbed in spontaneously hypertensive rats (SHR), and 3) excess dietary NaCl elevates plasma sodium concentration in SHR. The results demonstrate that plasma sodium has a circadian rhythm that is inversely related to the circadian rhythm of arterial pressure. Although the plasma sodium rhythms of SHR and control rats are nearly identical, the plasma sodium concentrations are significantly higher in SHR throughout the 24-h cycle. Maintenance on a high-NaCl diet increases plasma sodium concentration similarly in both SHR and control rats, but it blunts the plasma sodium rhythm only in SHR. These results demonstrate that in rats, plasma sodium has a circadian rhythm and that high-NaCl diets increase plasma sodium concentration.     

Injection of plasma into the Trimyx Galathea

The Galathea-3 device, which consists of a coaxial plasma gun, a plasma guide, a lock chamber, and the Trimyx Galathea confinement system with three myxines, is briefly described. The plasma parameters at the outlet from the plasma gun, in the plasma guide, and in the confinement system are presented. It is shown that the plasma can be efficiently entrapped into the Galathea and spread out along it. The confined plasma is found to go beyond the Ohkawa surfaces. Estimates show that the particle losses from the system are on the order of the classical ones.     

The use of Doppler reflectometry in the L-2M stellarator

Results are presented from measurements of the plasma rotation velocity and plasma density fluctuations in the L-2M stellarator by the method of Doppler reflectometry. Specific problems that arise when applying this diagnostics to the stellarator are revealed. The poloidal plasma velocity at the periphery of the plasma column is determined. The results of measurements are well reproducible.     

Emission of low-frequency electromagnetic waves by a short laser pulse propagating in a plasma with density fluctuations

It is shown that a short laser pulse propagating in a plasma with electron density fluctuations can emit electromagnetic waves with frequencies much lower than the laser carrier frequency. Emissions with frequencies close to the plasma frequency and the doubled plasma frequency in a nonisothermal plasma, as well as emission generated in a turbulent plasma, are examined. The effects in question are related to the transformation of the laser pulse wakefield into electromagnetic radiation by electron density fluctuations. The phenomenon under study opens new possibilities for diagnostics of both plasma fields excited by laser pulses and electron density fluctuations in a plasma.     

Generalized scale invariance and log-Poisson statistics for turbulence in the scrape-off-layer plasma in the T-10 tokamak

Results are presented from experimental observations of the statistical properties of scrape-off-layer plasma turbulence in the T-10 tokamak. The experimentally observed fluctuations in the fluxes and plasma density are intermittent in nature and obey a non-Gaussian statistics. The generalized property of plasma turbulence is its scale invariance. The experimental scalings for the moments of the distribution function of the difference in the amplitudes of fluctuations in the fluxes and plasma density are described by the log-Poisson model of strong turbulence. The self-similarity properties of turbulence that are associated with the topology of dissipative structures are investigated.     

Theory of Electromagnetic Surface Waves in Plasma with Smooth Boundaries

A theory of nonpotential surface waves in plasma with smooth boundaries is developed. The complex frequencies of surface waves for plasma systems of different geometries and different profiles of the plasma density are calculated. Expressions for the rates of collisionless damping of surface waves due to their resonance interaction with local plasma waves of continuous spectrum are obtained. The influence of collisions in plasma is also considered.     

Diagnostics of plasma oscillations by the field of surface waves guided by a dielectric waveguide

The potentialities of the diagnostic method for determining the plasma parameters by recording the surface waves guided by a dielectric waveguide and scattered by plasma oscillations are discussed. The use of surface (slowed) waves makes it possible to improve both the sensitivity and spatial resolution of measurements. The scattering is the most intense near the waveguide cutoff, at which the dependence of the wave propagation constant on the plasma density is the steepest. It is shown experimentally that the method proposed makes it possible to determine the discharge plasma density and electron energy and to estimate the amplitude of the RF field of the plasma waves forming the discharge and the amplitude of plasma density oscillations in these waves. The data obtained from the measurements of the amplitudes of both high-and low-frequency plasma density oscillations by the proposed method agree satisfactorily with theoretical predictions. The experimental data on the plasma density are confirmed by other diagnostic measurements. The ways of reducing measurement errors are proposed.     

Studies on the synthesis of liver phospholipids and the turnover of plasma phospholipids in non pregnant female rats using radioactive palmitate.

Using the tracer method and a compartmental model we found that 0.9 mumoles plasma free fatty acids per min are esterified to liver phospholipids. The turnover rate of plasma phospholipid fatty acids was determined to be 0.5 mumoles phospholipid fatty acids per min. The turnover time of the plasma phospholipid fatty acids was calculated to be 0.9 hours. The results indicate that only 69 per cent of plasma free fatty acids esterified to liver phospholipids are secreted by the liver into the plasma.     

Charge and potential of a dust grain versus the intergrain distance and establishment of the latter in a low-pressure plasma

Results from experimental studies of ordered dust structures in plasma are reviewed. The experimental conditions and the data on the grain size and intergrain distance in plasma dust crystals are analyzed. It is shown that intergrain distance is a function of the grain size. The range of the ratio of the dust grain size to the Debye radius within which plasma dust crystals can form is determined. A volume cell surrounding a dust grain in plasma is considered. It is found that the potential and charge of the grain depend substantially on the intergrain distance. The charge, potential, and potential energy of a dust grain in a plasma dust crystal, as well as the electrostatic force exerted by the plasma field on the grain, are calculated by the method of molecular dynamics as functions of the intergrain distance. The corresponding analytic approximations and the criterion for the establishment of a steady-state intergrain distance are proposed.     

Multiple glutathione S-transferase isoforms are present on male germ cell plasma membrane.

Phase II detoxification enzymes, the glutathione S-transferases (GSTs) of 24 kDa are known to be cytosolic enzymes. This study shows that multiple GST isoforms that are 24 kDa in size are present on the extracellular side of the plasma membrane of rat male germ cells. The GST activity of male germ cell plasma membranes is several folds higher than somatic cell plasma membrane GST activity. Isoform composition of the germ cell plasma membrane and the cytosolic pool differ, GSTM5 and GSTPi being absent on the plasma membranes. The molecular masses of the common isoforms are comparable between the two pools and both pools show GST and glutathione peroxidase activity.     

A method for calculating the effective charge of ions decelerated in a hot dense plasma

A method for calculating the effective charge of fast ions decelerated in a hot dense plasma is proposed. The method is based on the known experimental dependence of the effective charge of an ion decelerated in cold matter on its velocity. The ion velocity in this dependence is replaced with the velocity of an ion relative to plasma electrons, averaged over the Fermi-Dirac distribution. Using results of numerical calculations performed in a wide range of plasma parameters (from a Maxwellian plasma to a fully degenerate one), a scale-invariant representation of the effective charge of a decelerating ion as a function of its initial velocity and the plasma temperature and density is obtained. An analytical formula fitting the calculated results to within 5% is derived. The obtained dependences of the effective charge are incorporated in the model describing deceleration of fast ions in plasma. Using this model, the stopping powers of krypton and lead ions in a relatively cold rarefied gas-discharge plasma and hot ICF plasma are calculated. The results of calculations are shown to agree satisfactorily with available experimental data.     

Microfield model of quasi-independent particles and nonideal plasma

An original model of a plasma microfield constructed from first principles is much more advantageous than the earlier ones. The validity of the model is confirmed by optical measurements. The thermodynamics of a gaseous plasma is qualitatively described by a new ionization equilibrium model in which the interaction between charged particles is accounted for by means of a self-consistent plasma microfield. Numerical simulations show that, in this new model, nonideal effects are insignificant even at high plasma densities, and there are no phase transitions in a gaseous plasma, a conclusion that agrees with experimental data. The model is tested against the popular models of nonideal plasma and the SESAM database.     

Development of an Exactly Solvable Model of Resonance Tunneling of Electromagnetic Waves through Gradient Barriers in a Nonuniform Magnetoactive Plasma

An exactly solvable one-dimensional model describing resonance tunneling (reflectionless transmission) of a transverse electromagnetic wave through wide layers of magnetoactive plasma is developed on the basis of the Helmholtz equation. The plasma layers include a set of spatially localized density structures the amplitudes and thicknesses of which are such that approximate methods are inapplicable for their analysis. The profiles of the plasma density structures strongly depend on the choice of the free parameters of the problem that determine the amplitudes of plasma density modulation, characteristic scale lengths of the density structures, their number, and the total thickness of the nonuniform plasma layer. The plasma layers can also include a set of random inhomogeneities. The propagation of electromagnetic waves through such complicated plasma inhomogeneities is analyzed numerically within the proposed exactly solvable model. According to calculations, there are a wide set of inhomogeneous structures for which an electromagnetic wave incident from vacuum can propagate through the plasma layer without reflection, i.e., the complete tunneling of thick plasma barriers takes place. The model also allows one to exactly solve a one-dimensional problem on the nonlinear transillumination of a nonuniform plasma layer in the presence of cubic nonlinearity. It is important that, due to nonlinearity, the thicknesses of the evanescent plasma regions can decrease substantially and, at a sufficiently strong nonlinearity, such regions will disappear completely. The problem of resonance tunneling of electromagnetic radiation through gradient wave barriers is of interest for various applications, such as efficient heating of dense plasma by electromagnetic radiation and transmission of electromagnetic signals from a source located in the near-Earth plasma or deep in the plasma of an astrophysical object through the surrounding evanescent regions.