准分子激光蒸发YBa2Cu,sub>3C7-x靶产生等离子体的膨胀过程研究

对XeCl准分子激光蒸发YBa2Cu3O7-x陶瓷靶产生的等离子体进行了实验和理论研究.利用发射光谱,分辨出等离子体内的各种粒子.并对各种粒子进行了飞行时间谱测量.在实验的基础上,建立了一个等离子体的膨胀模型.计算结果与实验符合较好.     

准分子激光蒸发YBa_2Cu_3C(7-x)靶产生等离子体的膨胀过程研究

对XeCl准分子激光蒸发YBa_2Cu_3O_(7-x)陶瓷靶产生的等离子体进行了实验和理论研究.利用发射光谱,分辨出等离子体内的各种粒子.并对各种粒子进行了飞行时间谱测量.在实验的基础上,建立了一个等离子体的膨胀模型.计算结果与实验符合较好.     

Electron-Bernstein-wave current drive in an overdense plasma at the Wendelstein 7-AS stellarator

Electron-Bernstein-wave (EBW) current drive in an overdense plasma was demonstrated at the Wendelstein 7-AS stellarator for the first time. The EBWs were generated by O-X-B mode conversion. The relatively high current drive efficiency was consistent with theoretical predictions. The experiments provided first investigations of EBW phase space interaction for wave refractive indices much larger than unity.     

Phase transition in electrorheological plasmas

Applying an external electric AC field to a dusty plasma, the micro-particles arrange in strings or chains. In analogy to electrorheological fluids, such a system is called electrorheological plasma. Turning gradually the AC field into a DC field, the string formation is diminished until it vanishes completely in the DC case. In this way, a cross-over transition from a string-like to an isotropic micro-particle many-body system can be investigated. Experimental investigations of electrorheological plasmas are performed under microgravity conditions in parabolic flights. For analysing the image data, a supervised machine learning code was developed and a continuous cross over was found. A molecular dynamics simulation showed qualitatively similar results but also some deviations from the experimental results.     

Forward plasma emission through laser–foil interaction with nanosecond lasers

Fundamental investigations of plasma diagnostics of a forward laser plasma acceleration employing laser–foil interactions were conducted for an Al-foil target irradiated with an Nd:YAG laser of 1 J/pulse with pulse width of 10 ns. Temporal evolutions of electron temperatures and densities were evaluated with electrostatic probes and spectroscopic diagnostics. From the results, it was shown that an average speed of ions in a forward direction was about 40 km/s. Also, it was shown that the plasma temperature and density were about 2.5–8 eV and 10¹⁰ cm⁻³, respectively.     

Electrolytic capacitor cathode foil finishing by ion-plasma methods

The results from investigations of TiN protective coatings formed on nanostructured cathode foil by means of plasma magnetron technologies and under irradiation by nitrogen plasma of a high-frequency inductive (HFI) discharge are presented. Their influence on the structure of coatings is demonstrated. Methods for controlling the ion energy and ion flux from an HFI plasma discharge onto a grounded substrate were studied. It was found that such regimes inevitably fail when uninsulated chamber walls and low working gas pressures are used.     

Effect of fine structure on the hydrogen permeability of iron

The results of some investigations into the penetration of hydrogen from a high-frequency hydrogen plasma through an iron sample are presented for a variety of hydrogen-absorption conditions. Certain anomalies encountered in the hydrogen-penetration characteristics are attributed to the fine structure of the metal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 18–21, November, 1976.     

Kinetic Description of the Stationary Band-Like Weakly Turbulent Beam Discharge Plasma in Hydrogen II. Budget of Ions and Metastables — Analysis of the Balance Equation System

In the first part [1] of our paper a kinetic model for the band-like beam discharge plasma in hydrogen was derived, numerically obtained results on the ionization and dissociation degree were presented and a detailed explanation of the influence of the electron kinetic properties on the macroscopic plasma behaviour was given. Continuing these investigations, we now report and discuss the results on the ion- and metastable atom-budget. On this basis an analysis is made of the resulting balance equation system with a view to finding the most important physical processes, and a simplified equation system is derived which allows to interpret the essential features of the macroscopic plasma properties.     

Stability of a rotating pinch

The problem of pinch stabilisation is of interest in connection with plasma confinement and has been the subject matter of various investigations in recent years, (Kruskal andSchwarzschild, Taylor, Shafranov). The theoretical investigations in the past have been restricted to static equilibrium configurations. It is of some interest to explore whether an initial motion of plasma tends to make the pinch more, or less stable than when the fluid velocity is zero. Keeping this in mind let us investigate theaxisymmetric stability of an infinitely long cylindrical plasma column of radiusR rotating uniformly with angular velocityΩ about theZ-axis, the fluid being assumed to the incompressible, inviscid, and of infinite electrical conductivity. The plasma carries a uniform axial current of densityj ₀ and a uniform axial magnetic fieldH ₁. The field outside is taken to beH ₂ inZ-direction and a toroidal component which is continuous across the boundary.     

Radiation Phenomena of Plasma Waves Part 3. Radiation from Finite Sources

Radiation phenomena of plasma waves has been reviewed in three parts, fundamental radiation theory, radiation from point sources, and radiation from finite sources. It is the author's impression that the theoretical prediction of the resonance cone by Kuehl (Phys. Fluids 5, 1095 [1962]) initiated much of the theoretical work. The experimental observation of the resonance cone by Fisher and Gould (Phys. Fluids 14, 857 [1971]) is an epoch-making work in the field of radiation problems from point sources. Although finite sources had been used for excitation of many plasma waves, the experimental confirmation of the radiation patterns from finite sources by Shen et al. (Rad. Sci. 5, 611 [1970]) has initiated much later work. Since thier investigations, radiation phenomena of plasma waves have been investigated and been made clear by many authors, as shown in this review paper Parts 1 - 3. The essential radiation phenomena from point sources have been clarified experimentally except for an observation of electromagnetic ion waves radiated from point sources. Radiation phenomena from finite sources will be investigated further because there are various sources required for various goals, e.g., for heating of plasma infusion devices, etc. These investigations will progress into nonlinear phenomena, instabilities, and inhomogenuous effects in plasmas. It is a great pleasure for the author of this review paper if he could give some insight or any help for further developments in plasma sciences.     

Space-Time Diagnostics of Reactive Impulse Plasma

Spectral investigations of the space-time distribution of reactive impulse plasma ejected from a coaxial accelerator were carried out. A two-zone structure of the plasmoid, related to interactions between the gas plasma and the accelerator electrode, was found. The isotropization kinetics of the chemical composition of the plasmoid was determined.     

Spatial structures of continuous microwave discharge

The paper deals with the results of investigations of spatial structures of continuous microwave discharge in a quasi-optical resonator. The results are given of experimental observations and easurements of the parameters of plasma in discharges of different forms, and the reasons are analyzed for the formation of spatial discharge structures. It is demonstrated that, as a result of the plasma-resonance amplification of the field, the discharge makes a transition to the contracted state with a size that is much less than the microwave-frequency wavelength and with an electron concentration in excess of the critical. It is found that the stratification of the contracted state across the electric field vector, which arises in some gases, is caused by the development of thermoelectric-current instability that was not previously observed in microwave discharges.     

A cadmium photoionization laser pumped by laser induced plasma radiation from a multi foci device

Soft x-rays from a laser-produced plasma were used to perform innershell photoionization of Cd atoms and to generate laser radiation at 442 nm. To achieve longer interaction zones between the Cd vapor and the soft x-ray flux, up to three plasma spots have been applied. In this way a maximum laser energy of 300 J with a 600 mJ Nd:YAG laser for the plasma production was achieved. Experimental investigations and corresponding rate-equation calculations indicate, that photoelectrons play an important role in the total laser kinetics.     

Transmission of microwaves through magnetoactive plasma

The possibility of transmission of microwaves through the plasma layer with an electron concentration of more than critical value is considered. The problem is solved by consideration of the interaction of a microwave with the plane layer of magnetoactive plasma. The problem is formulated by such a way as to obtain the estimation of the greatest lower bound of microwave transmission coefficient through the plasma layer. The results of numerical parametric investigations are applied for the transparency conditions of the shock wave plasma in space communication. The possibility of stable (without interruptions) microwave communication through the shock wave plasma is demonstrated     

Plasma density measurement in an electrical discharge distributed in a liquid

An attempt is made to directly measure the density of a plasma forming in an electrical discharge initiated in a liquid. Microwave methods of plasma diagnostic are applied in investigations of such a kind for the first time. The rate of rise of the plasma density is found to be comparable to the rate of rise of the ionization by electron impact.     

Plasma Erosion Opening Switch in the Double-Pulse Operation Mode of a High-Current Electron Accelerator

This paper reports the results of investigations of the operation of a fast current opening switch, with a 1013-1016 plasma density produced either by dielectric surface flashover or by explosive emission of graphite. A series of two pulses was applied to two diodes in parallel. The first pulse produced plasma in the first diode which closed that diode gap by the arrival time of the second pulse. The first, shorted, diode then acted as an erosion switch for the second pulse. A factor of 2.5-3 power multiplication was obtained under optimum conditions. The opening-switch resistance during the magnetic insulation phase, neglecting the electron losses between the switch and the generating diode, exceeded 100 ?. The duration of the rapid opening phase was less than 5 ns under optimum conditions. This method of plasma production does not require external plasma sources, and permits a wide variation of plasma density, which in turn allows high inductor currents and stored energies.     

Laser-induced ignition by optical breakdown

This paper is an experimental work of the applied methodical character in which as an attempt to optimize a laser ignition system a systematic study of the best incoupling geometry for the employed Nd:YAG laser was performed. The incoupling geometry comprises the pump fiber and an aspheric collimating lens. In this context, the distance between pump fiber and collimating lens was made continuously variable. The distance between fiber and lens primarily influences the diameter of the pump beam. In this way, it is possible to control the pulse energy as well as the number of pulses generated within a pump cycle. Furthermore, investigations to analyze the focal size dependence of plasma generation were carried out. As a result, it was found that it is possible to reduce optical losses caused by plasma transmission by choosing an optimum focal volume. This experiment was carried out for different pressures and focal volumes.     

Structures of the particles of the condensed dispersed phase in solid fuel combustion products plasma

The results of experimental investigations of a type of dusty plasma which has been least studied—the plasma of solid fuel combustion products—were presented. Experiments to determine the parameters of the plasma of the combustion products of synthetic solid fuels with various compositions together with simultaneous diagnostics of the degree of ordering of the structures of the particles of the dispersed condensed phase were performed. The measurements showed that the charge composition of the plasma of the solid fuels combustion products depends strongly on the easily ionized alkali-metal impurities which are always present in synthetic fuel in one or another amount. An ordered arrangement of the particles of a condensed dispersed phase in structures that form in a boundary region between the high-temperature and condensation zones was observed for samples of aluminum-coated solid fuels with a low content of alkali-metal impurities.     

Photographic observation of aluminum micropellet ablation in theMT-1M tokamak plasma

Laser beam accelerated aluminum micropellets were injected into the MT-1M tokamak plasma, and the distribution of characteristic line radiation of aluminum atoms and ions of different charge state was detected. The investigations are focused on the visualization of the pellet cloud, on the bending of the pellet path, and on the striation occurring in the radiation of different charge state along the pellet path in the plasma