全电离氢等离子体的电导率

主要研究了全电离等离子体的散射相移、传输截面和电导率.相移应用WKB方法计算,且计算结果与使用精确计算方法得到的结果非常一致,证明了所用计算方法的正确性和准确性.在对传输截面的计算中,观察到了形状共振,这种共振是由于半束缚态的消失产生的.电导率的计算应用了Chapman-Enskog方法,并与其它理论和实验结果进行了比较.     

Behaviour of fully ionized seed plasma excited by microwave

Nonequilibrium plasmas with cesium metal vapor ionization in helium and argon gases at moderate pressures are excited with microwave power. The structures and behaviour of the seeded plasmas are experimentally examined, particularly under the condition of Full seed (cesium atoms) ionization. By cesium seeding, the minimum power sustaining the plasma is reduced markedly, and both a broad plasma observed in pure helium and unsteady filament-like plasmas in pure argon change to the steady and broad plasma locating close to the inner surface of a discharge tube, it is revealed from the electron temperature measurements that the plasma can be in the regime of full seed ionization for suitable microwave powers, where the electron density is kept almost constant. The thickness of the fully ionized seed (FIS) plasma decreases with increasing the mole fraction of cesium vapor, and is almost independent of noble gas pressure. The thickness almost coincides with the skin depth determined from the electrical conductivity almost uniform in the FIS plasma. These facts suggest that the FIS plasma will be easily produced and maintained as long as the microwave power is consumed to the electron heating     

Energy deposition of fast α particles in a fully ionized deuterium-tritium plasma

An α particle transport equation has been solved analytically in one-dimensional spherical geometry when the plasma properties are uniform in space and time. The results agree well with earlier results.     

Self-focusing of elliptically shaped high-power laser beams in a fully ionized plasma

The effect of self-focusing of a high-power light beam with an elliptical cross-section in a strongly ionised plasma has been evaluated. The mechanism of self-focusing considered is non-uniform heating of plasma by an electromagnetic wave having transverse variation of amplitude along its wave front. The heating causes redistribution of carriers which lead to a nonlinear relationship between the electron density and the electric vector and hence to a field-dependent effective dielectric constant. It is found that the beam gets focused at different focal points in different directions exhibiting the effect of astigmatism. There are several critical powers, below thex=0,y=0 planes; at higher powers one dimension focuses while the other defocusses, an oscillatory waveguide is formed in both dimensions. Above the highest critical power both dimensions self-focus, the dimensionless beam width parametersf ₁ andf ₂ forx andy focusing reach different minima corresponding to different self-focusing distances beyond which both dimensions continue diverging. The effect of energy loss through absorption from the beam has also been considered. It has been observed that absorption brings about a reduction in the extent of self-focusing and favours defocusing of the beam.     

Electrical conductivity of nonideal hydrogen plasma at megabar dynamic pressures

The electrical conductivity of a nonideal hydrogen plasma is measured under shock-wave compression to pressures ∼1.5 Mbar. It is found that the conductivity increases sharply (by five orders of magnitude) at a density ρ∼0.3−0.4 g/cm³, reaching close to liquid-metal values ∼10³ S/cm. The data obtained can be described by a nonideal-plasma model taking into account the increase in the number of conduction electrons as a result of “ionization by pressure.” Pis’ma Zh. éksp. Teor. Fiz. 69, No. 12, 874–878 (25 June 1999)     

Electrical conductivity of a strongly coupled hydrogen plasma

A kinetic theoretic calculation of the dc conductivity of a strongly coupled, semi-classical hydrogen plasma yields results in reasonable agreement with recent simulations. A closed formula is derived which extends the standard Spitzer result into the strong coupling regime.     

Electrical conductivity and thermal EMF of CsI at high pressures

Abstract

The pressure dependence of thermal EMF and the resistivity-temperature dependence of CsI has been measured at pressures 20-50 GPa. In CsI non-monotonous change of resistivity, thermal EMF and activation energy of charge carriers has been observed at pressures above 40 GPa. The sign of thermal EMF corresponds to the electron conductivity. At pressures below 47 GPa the resistivity-temperature dependence is of the type characteristic of non-degenerate semiconductors, at pressure above 49 GPa it is characteristic of degenerate semiconductors (or metals). The observed properties are connected probably with the continuous distortion of B2 to an hcp-like phase.     

Scattering processes and electrical conductivity of partially ionized hydrogen plasma

We consider partially ionized hydrogen plasma for the density region n_e = (10¹⁸ ÷ 10²²) cm^—3. The cross sections for scattering processes between the particles are calculated within the partial wave method. Charged particles in the system (electrons, protons) interact via an effective potential that takes into account threeparticle correlations. The Buckingham polarization potential is used to describe electron‐atom and proton‐atom interactions. The electrical conductivity is determined using the Chapman‐Enskog method. The results are compared with other available data.     

Electrical conductivity of MgCO3 at high pressures and high temperatures

The electrical conductivity of polycrystalline magnesite (MgCO₃) was measured at 3-6 GPa at high temperatures using complex impedance spectroscopy in a multi-anvil high-pressure apparatus. The electrical conductivity increased with increasing pressure. The activation enthalpy calculated in the temperature range 650-1000 K also increased with increasing pressure. The effect of pressure was interpreted as being the activation volume in the Arrhenius equation, and the fitted data gave an activation energy and volume of 1.76±0.03 eV and −3.95±0.78 cm³/mole, respectively. The negative activation volume and relatively large activation energy observed in this study suggests that the hopping of large polarons is the dominant mechanism for the electrical conductivity over the pressure and temperature range investigated.     

Electrical conductivity and relaxation processes in aluminum oxide at high temperatures

The current decay and potential distribution in polycrystalline aluminum oxide were studied in the temperature range 800–1200 °C in air and in oxygen. The temperature dependence of the resistance was determined in oxidizing and neutral media. Only cations participate in the conduction. The medium has an effect only in the impurity-conductivity region.Translated from Izvestiya VUZ. Fizika, No. 3, pp. 57–61, March, 1970.     

Electrical conductivity anisotropy in alkali feldspar at high temperature and pressure

The electrical conductivity of alkali feldspar along different orientations was determined at 1.0 GPa and at temperatures of 823–1286 K in a cubic anvil apparatus using alternating current impedance spectroscopy. Impedance arcs representing crystal conductivity occur in the frequency range of ～10³–10⁶ Hz. The electrical conductivity of alkali feldspar increases with increasing temperature. The highest electrical conductivities in alkali feldspars were measured along the a-axis, with somewhat lower conductivities along the b-axis, and the lowest conductivities along the c-axis, suggesting minor anisotropy. The activation enthalpies ranged from 100 to 110 kJ/mol. The anisotropic results were combined to yield an isotropic model with an activation enthalpy of 102 kJ/mol. By comparing these results with previous results, we suggest that the dominating charge carriers for alkali feldspars are alkali ions. The minor anisotropy in conductivity for alkali feldspar may not account for the anisotropy of the crust.     

Measurements of the electron concentration and conductivity of a partially ionized inert gas plasma

A theoretical model for the resonant hyper-Raman scattering in semiconductor crystals is presented. The Wannier excitons are considered as intermediate states. The expressions for the resonant hyper-Raman scattering cross section are obtained. The theoretical model developed allows taking into account different mechanisms of the exciton-photon and exciton-phonon interactions.     

Electrical conductivity of magnetite at low temperatures

Measurements of the electrical conductivity as a function of temperature down to liquid helium temperature are reported for four single crystal specimens of magnetite, Fe₃O₄, differing in impurity content and in stoichiometry. Such variations have little effect on the low temperature electrical properties.