ANSYS在气体探测器电场分布计算中的应用

介绍了气体探测器电场分布的计算方法,以计算MSGC探测器单元电场分布为例说明了如何用ANSYS软件包来计算结构较复杂的气体探测器内部电场分布,同时讨论了电场分布对气体探测器性能的影响.     

Specific features of the thermodynamic equilibrium state of a thin water film in an electric field of surface active centers of a mica crystal

The structural features of a thin polar liquid film in an electric field of a charged substrate have been theoretically investigated using methods of statistical physics. It has been established that electrical interactions in this system lead to a change in the structure of the polar liquid and to the formation of clusters in it. A self-consistent nonlinear equation has been derived for describing the distribution of the potential and strength of the electric field inside the film under investigation. The depth of penetration of this field into the liquid medium has been studied as a function of the electrical activity of the substrate, temperature, degree of polarity of the liquid, and concentration of interface heterocharges. It has been revealed that the extent of structured regions in the liquid increases with an increase in the potential gradient of the internal field and with a decrease in the temperature.     

Features of superconducting transition in nanocomposite consisting of “insulating matrix (porous alkali-borosilicate glass)” – “granular metallic filler (indium)”

Patterns in temperature and magnetic field behavior of the electrical resistance of nanocomposite consisting of “insulating matrix (7 nm-pore alkali-borosilicate glass)” – “granular metallic filler (indium)” (PG7+In) has been found and analyzed in the vicinity of superconducting transition. Insulating behavior in the electrical resistivity has been observed in a normal state. External magnetic field shifts the transition to lower temperatures and the same time gradually strengths the insulating behavior above the superconducting transition. Hopping conductivity mechanism developed for the granular conductor systems can be responsible for the insulating behavior in normal-state electrical resistance. Electron hopping in the granular conductor system is realized as tunneling of electrons through intergranular contacts between the metallic granules. The superconducting transition has been found to be rather broad. Broadening in the superconducting transition can be attributed to fluctuation conductivity. Above the superconducting transition, the Aslamazov-Larkin contribution to the conductivity characteristic for three-dimensional systems has been found to be main correction to the conductivity.     

Electrical transport mechanism in Al/V2O5/Al microdevices

The current-voltage characteristics of metal-insulator-metal microdevices fabricated with electron-beam evaporated vanadium pentoxide films have been studied in order to understand the electrical transport mechanism in these films. The dependence of transport properties on various factors such as film thickness, substrate temperature, and applied field, has been established. The results revealed that the electrical transport follows a Schottky-type mechanism at lower electrical fields and a Poole-Frenkel-type at higher electrical fields than 2×10⁶ V/m.     

Specific features of the dielectric response of heterogeneous systems with a polar matrix containing electrically active inclusions

A theoretical model has been proposed which makes it possible to introduce the correction into the complex permittivity of electrically active condensed systems that contain a polar liquid matrix and low-dimensional solid particles with a developed electrically active surface. It has been established that there is an interfacial electrical interaction between surface charges of the solid component and polar molecules of the liquid matrix. The processes occurring during this interaction lead to the appearance of an intrinsic internal electric field in the system under investigation. The contribution from surface effects to the formation of the polarized state of the polar liquid medium has been investigated in terms of the proposed model. The possibility of controlling the processes of local change in the structure of the polar liquid component under the effect of the internal electric field by varying the electrically active specific surface area of the solid phase and the intrinsic dipole moment of molecules of the liquid matrix has been analyzed in the studied systems. The conditions providing for the appearance of a controlled potential gradient of the internal electric field have been determined for the dispersed systems under consideration. The parameter that makes it possible to evaluate the contribution from the interfacial electrical contact interaction to the dielectric response of the liquid component and the entire system has been introduced for the first time.     

The effect of pulsed electric fields on biological cells:experiments and applications

The effect of pulsed electric fields with amplitudes in the range of 100 V/cm-100 kV/cm on bacteria and aquatic nuisance species has been explored. The pulse duration was so short that heating of the biological matter could be neglected. The electrical energy required for lysing of bacteria, or stunning of aquatic species, decreases when the pulse duration is reduced. For lysing of Eschericia coli, this tendency has been proven to hold for pulsewidths as short as 60 ns. For macroorganisms, however, it was found that for pulsewidths of less than 5 μs, the tendency is reversed: the energy required to affect the macroorganisms increases again. This minimum in energy, or maximum in efficiency, respectively, can be understood by taking the time required for electrical charging of the cell membrane into account. Applications of the pulsed electric field technique (PEFT) are in biofouling prevention, debacterialization of liquids, and in the field of medicine. A series of field tests on biofouling prevention in a cooling system with untreated water as coolant has demonstrated the economic feasibility of the electro-technology     

Unveiling Informational Properties of the Chen-Ouillon-Sornette Seismo-Electrical Model

The seismo-electrical coupling is critical to understand the mechanism of geoelectrical precursors to earthquakes. A novel seismo-electrical model, called Chen–Ouillon–Sornette (COS) model, has been developed by combining the Burridge–Knopoff spring-block system with the mechanisms of stress-activated charge carriers (i.e., electrons and holes) and pressure-stimulated currents. Such a model, thus, can simulate fracture-induced electrical signals at a laboratory scale or earthquake-related geoelectrical signals at a geological scale. In this study, by using information measures of time series analysis, we attempt to understand the influence of diverse electrical conditions on the characteristics of the simulated electrical signals with the COS model. We employ the Fisher–Shannon method to investigate the temporal dynamics of the COS model. The result showed that the electrical parameters of the COS model, particularly for the capacitance and inductance, affect the levels of the order/disorder in the electrical time series. Compared to the field observations, we infer that the underground electrical condition has become larger capacitance or smaller inductance in seismogenic processes. Accordingly, this study may provide a better understanding of the mechanical–electrical coupling of the earth’s crust.     

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在非对称磁镜场微波ECR等离子体中引入了磁电加热系统,研究了电极环大小、轴向位置以及双环加热对离子温度的影响.结果表明,大小合适的电极环能有效提高离子的加热温度,且最优电极环尺寸主要取决于离子回旋半径.电极环轴向位置的选择主要与磁镜场位形有关,将电极环置于磁镜场中部的弱磁场位置时最有利于离子温度的提高.采用双电极环加热能进一步提高离子温度,并且其加热效果是单环加热的两倍.     

Effect of selenium on the thermoelectric properties of tellurium

The effect of selenium, in amounts varying up to 3 pct. wt. on the electrical conductivityσ and the thermal emfα of tellurium was studied over a wide temperature range. As a result of this study, these properties of the tellurium -selenium system have been found to follow extremal trends. The alloy containing 0.25% Se has the maximum electrical conductivity and the minimum thermal emf. The true change inα at the melting point is estimated from the crystallization rate of test specimens in a constant electric field.     

Effect of low electrical potentials on the microhardness of metallic materials

The effect of low (<5 V) electrical potentials on the microhardness of metallic materials has been studied experimentally. It has been revealed that this effect does depend on the sign of the electric field potential. It has been found that the microhardness of aluminum, cobalt, and zinc decreases and the microhardness of zirconium and iron increases when an electrical potential is applied. It has been argued that the degree of microhardness change under an electric field depends on the magnitude of applied potential, the magnitude of the Hall coefficient of a metal, and its physicochemical properties.     

Superconducting properties of tin embedded in nanometer-sized pores of glass

The electrical resistance of tin embedded from a melt in porous glasses with an average pore diameter of ??7 nm has been investigated at low temperatures in magnetic fields up to 2 T. The temperatures of the transition to the superconducting state for nanocrystalline tin have been determined in magnetic fields of 0, 0.3, 0.5, 1.0, 1.5, and 2.0 T. It has been found that the temperature and magnetic-field dependences of the electrical resistance of the nanocomposite under investigation exhibit two transitions to the superconducting state. The nature of the double superconducting transitions has been discussed. The H _c -T _c phase diagram has been constructed using the entire set of data on the magnetic-field and temperature dependences of the electrical resistance of nanostructured tin. This phase diagram indicates that the upper critical magnetic field H _c2(0) for nanostructured tin is almost two orders of magnitude higher than the corresponding field for bulk tin.     

Correlation of electrical, magnetic, and thermal properties of the La0.85Ag0.15MnO3 manganite near the phase transition temperature

The correlation between electrical, magnetic, and lattice properties of manganites has been studied by analyzing the temperature dependence of the electrical resistivity of the La_0.85Ag_0.15MnO₃ manganite. The results have been discussed within the model of a phase-separated manganite in terms of the percolation theory. It has been shown that, from analyzing the temperature and magnetic field dependences of the electrical resistivity, it is possible to predict the behavior of the magnetization and specific heat, as well as the change of magnetic entropy near the phase transition temperature, and that the obtained agreement with experimental data for this analysis is quite reasonable.     

Dielectric breakdown phenomena in Al2O3 filled DGEBA/MDA/SN composite system

Dielectric breakdown phenomena by electrical treeing deterioration was investigated in the new epoxy resin system DGEBA/MDA/SN filled with Al₂O₃. As the filler content increased, the maximum electric field at breakdown increased and then decreased with increase of defects such as voids, impurities and delamination or peeling between filler and matrix. As the electrode separation increased, the breakdown voltage increased, but the breakdown strength decreased and then saturated to 17 kV/mm. Also, the maximum electric field at the tip when the system was failed increased. The electrical tree initiated from the side of the needle electrode was not from the tip where the reinforced field is the highest. The electrical tree was blocked by the filler. The interface condition of filler and polymer matrix played an important role in the electrical treeing resistance. The final breakdown phenomena showed fan-type crack as observed in the non-filled system.     

Mesoscopic temporary devices: a multiple tip experiment on a silicon surface

A cantilever device with two gold coated silicon tips has been used to create two point contacts on a silicon surface. The lateral distance between the tips is 10 μm. The tips are independently movable in vertical direction and the contact force is defined. While the contacts are closed, a complete set of electrical characteristics of the system is measured. An Ohmic current and a field dependent current are found, so the system behaves like a FET. The measured set of curves was fit with a MESFET model. A weak coupling between the bulk material and the current carried through surface states is found.     

Resistivity superconducting transition in single-crystalline Cd0.95Ni0.05Sb system consisting of non-superconducting CdSb and NiSb phases

Resistivity superconducting transition has been for the first time found in single crystal of two-component 0.95(CdSb)–0.05(NiSb) system. End members of the system are not superconductors under normal conditions. Insulating behavior in temperature dependence of the electrical resistivity, which is due to hopping conductivity, precedes the transition. The resistivity superconducting transition is rather broad, since at cooling down the electrical resistivity starts to fall at 10.5 K, whereas zero resistivity is reached only at ~2.3 K. Longitudinal magnetic field gradually depresses superconductivity and shifts the superconducting transition to lower temperatures. Under magnetic field above 0.5 T, superconductivity is totally destroyed. Main features observed in the resistivity superconducting transition, including its unusually big width and insulating electrical behavior above the transition, can be related to inhomogeneity of the single crystal studied. According to XRD and SEM examinations, the single crystal consists of major CdSb phase and minor NiSb phase. The NiSb phase forms inhomogeneities in the CdSb matrix. Micro-sized needle-like NiSb crystals and nano-sized Ni_1-xSb_x clusters can be considered as typical inhomogeneities.     

The study of the ionic wind blower with multi-needles/ring type electrodes disposed on inner wall of the cylindrical blower

Corona discharge is one of many methods that convert electrical power into mechanical force. It has been studied for various industrial fields because of its many advantages over conventional motor, such as its no moving parts, simpler structure, minimizing size and so on. In this paper, a discharge system with multiple corona electrodes disposed in a ring format, is studied by focusing on the electrical and mechanical characteristics. Effective ionic wind generation is due to the corona discharge which depends on electric field. Therefore, the electric field is affected by the voltage, discharge spacing, and distance between each corona electrodes.     

Thermal, structural and complex impedance analysis of Mn modified BaTiO3 electroceramic

The polycrystalline samples of BaTi_1−xMn_xO₃ (BMT) ferroelectric ceramics with x=0, 0.04, 0.07, 0.10 have been prepared using a solid-state reaction technique. The calcination temperature of the samples was optimized by thermal gravimetric analysis and repeated firing. Preliminary structural study using X-ray diffraction technique at room temperature suggests that structure of Mn modified compounds (BMT) change into orthorhombic crystal system from tetragonal crystal system. The field emission scanning electron micrographs (FE-SEM) show uniform grain distribution throughout the surface of the samples. Complex impedance analysis (CIS) has been carried out to investigate the electrical properties of BMT. The real and imaginary part of complex impedance plots exhibit semicircle(s) in the complex plane. The bulk resistance of the material decreases with rise in temperatures similar to a semiconductor. The variation of bulk ac conductivity with frequency shows that the compounds exhibit dispersive type electrical conductivity.     

Electrical properties of AgSnSbSe<Subscript>3</Subscript> under different external effects

The electrical properties of the chalcogenide AgSnSbSe₃ have been investigated over a wide range of variations in external parameters, such as the temperature, the pressure, and the frequency of the electric field. It has been found that the temperature dependence of the permittivity and the dependence of the electrical resistivity on the hydrostatic pressure exhibit anomalies that are characteristic of structural phase transitions. The influence of the frequency on dielectric properties of the material has been analyzed.     

Magnetic and transport properties of some light rare earth tungstates

Measurements relating to molar magnetic susceptibility, dc electrical conductivity and thermoelectric power of Nd, Sm, Eu and Gd are reported. The ac electrical conductivity at a few temperature ranges is also given. It is found that it follows the Curie-Weiss law behaviour and this has been attributed to the crystal field effect. The experimental value of Bohr magneton for the magnetic ions has been found to be in good agreement with theory. Thermoelectric power is negative in the measured temperature range suggesting these materials to bep-type semi-conductors and holes as the dominant charge carriers. The results are explained using band theory.