Electric current

About: Electric current is a research topic. Over the lifetime, 11950 publications have been published within this topic receiving 174422 citations. The topic is also known as: current & electrical current.

Gas Discharge Physics

Abstract: 1. Introduction.- 1.1 What Is the Subject of Gas Discharge Physics.- 1.2 Typical Discharges in a Constant Electric Field.- 1.3 Classification of Discharges.- 1.4 Brief History of Electric Discharge Research.- 1.5 Organization of the Book. Bibliography.- 2. Drift, Energy and Diffusion of Charged Particles in Constant Fields.- 2.1 Drift of Electrons in a Weakly Ionized Gas.- 2.2 Conduction of Ionized Gas.- 2.3 Electron Energy.- 2.4 Diffusion of Electrons.- 2.5 Ions.- 2.6 Ambipolar Diffusion.- 2.7 Electric Current in Plasma in the Presence of Longitudinal Gradients of Charge Density.- 2.8 Hydrodynamic Description of Electrons.- 3. Interaction of Electrons in an Ionized Gas with Oscillating Electric Field and Electromagnetic Waves.- 3.1 The Motion of Electrons in Oscillating Fields.- 3.2 Electron Energy.- 3.3 Basic Equations of Electrodynamics of Continuous Media.- 3.4 High-Frequency Conductivity and Dielectric Permittivity of Plasma.- 3.5 Propagation of Electromagnetic, Waves in Plasmas.- 3.6 Total Reflection of Electromagnetic Waves from Plasma and Plasma Oscillations.- 4. Production and Decay of Charged Particles.- 4.1 Electron Impact Ionization in a Constant Field.- 4.2 Other Ionization Mechanisms.- 4.3 Bulk Recombination.- 4.4 Formation and Decay of Negative Ions.- 4.5 Diffusional Loss of Charges.- 4.6 Electron Emission from Solids.- 4.7 Multiplication of Charges in a Gas via Secondary Emission.- 5. Kinetic Equation for Electrons in a Weakly Ionized Gas Placed in an Electric Field.- 5.1 Description of Electron Processes in Terms of the Velocity Distribution Function.- 5.2 Formulation of the Kinetic Equation.- 5.3 Approximation for the Angular Dependence of the Distribution Function.- 5.4 Equation of the Electron Energy Spectrum.- 5.5 Validity Criteria for the Spectrum Equation.- 5.6 Comparison of Some Conclusions Implied by the Kinetic Equation with the Result of Elementary Theory.- 5.7 Stationary Spectrum of Electrons in a Field in the Case of only Elastic Losses.- 5.8 Numerical Results for Nitrogen and Air.- 5.9 Spatially Nonuniform Fields of Arbitrary Strength.- 6. Electric Probes.- 6.1 Introduction. Electric Circuit.- 6.2 Current-Voltage Characteristic of a Single Probe.- 6.3 Theoretical Foundations of Electronic Current Diagnostics of Rarefied Plasmas.- 6.4 Procedure for Measuring the Distribution Function.- 6.5 Ionic Current to a Probe in Rarefied Plasma.- 6.6 Vacuum Diode Current and Space-Charge Layer Close to a Charged Body.- 6.7 Double Probe.- 6.8 Probe in a High-Pressure Plasma.- 7. Breakdown of Gases in Fields of Various Frequency Ranges.- 7.1 Essential Characteristics of the Phenomenon.- 7.2 Breakdown and Triggering of Self-Sustained Discharge in a Constant Homogeneous Field at Moderately Large Product of Pressure and Discharge Gap Width.- 7.3 Breakdown in Microwave Fields and Interpretation of Experimental Data Using the Elementary Theory.- 7.4 Calculation of Ionization Frequencies and Breakdown Thresholds Using the Kinetic Equation.- 7.5 Optical Breakdown.- 7.6 Methods of Exciting an RF Field in a Discharge Volume.- 7.7 Breakdown in RF and Low-Frequency Ranges.- 8. Stable Glow Discharge.- 8.1 General Structure and Observable Features.- 8.2 Current-Voltage Characteristic of Discharge Between Electrodes.- 8.3 Dark Discharge and the Role Played by Space Charge in the Formation of the Cathode Layer.- 8.4 Cathode Layer.- 8.5 Transition Region Between the Cathode Layer and the Homogeneous Positive Column.- 8.6 Positive Column.- 8.7 Heating of the Gas and Its Effect on the Current-Voltage Characteristic.- 8.8 Electronegative Gas Plasma.- 8.9 Discharge in Fast Gas Flow.- 8.10 Anode Layer.- 9. Glow Discharge Instabilities and Their Consequences.- 9.1 Causes and Consequences of Instabilities.- 9.2 Quasisteady Parameters.- 9.3 Field and Electron Temperature Perturbations in the Case of Quasisteady-State Te.- 9.4 Thermal Instability.- 9.5 Attachment Instability.- 9.6 Some Other Frequently Encountered Destabilizing Mechanisms.- 9.7 Striations.- 9.8 Contraction of the Positive Column.- 10. Arc Discharge.- 10.1 Definition and Characteristic Features of Arc Discharge.- 10.2 Arc Types.- 10.3 Arc Initiation.- 10.4 Carbon Arc in Free Air.- 10.5 Hot Cathode Arc: Processes near the Cathode.- 10.6 Cathode Spots and Vacuum Arc.- 10.7 Anode Region.- 10.8 Low-Pressure Arc with Externally Heated Cathode.- 10.9 Positive Column of High-Pressure Arc (Experimental Data).- 10.10 Plasma Temperature and V - i Characteristic of High-Pressure Arc Columns.- 10.11 The Gap Between Electron and Gas Temperatures in "Equilibrium" Plasma.- 11. Suslainment and Production of Equilibrium Plasma by Fields in Various Frequency Ranges.- 11.1 Introduction. Energy Balance in Plasma.- 11.2 Arc Column in a Constant Field.- 11.3 Inductively Coupled Radio-Frequency Discharge.- 11.4 Discharge in Microwave Fields.- 11.5 Continuous Optical Discharges.- 11.6 Plasmatrons: Generators of Dense Low-Temperature Plasma.- 12. Spark and Corona Discharges.- 12.1 General Concepts.- 12.2 Individual Electron Avalanche.- 12.3 Concept of Streamers.- 12.4 Breakdown and Streamers in Electronegative Gases (Air) in Moderately Wide Gaps with a Uniform Field.- 12.5 Spark Channel.- 12.6 Corona Discharge.- 12.7 Models of Streamer Propagation.- 12.8 Breakdown in Long Air Gaps with Strongly Nonuniform Fields (Experimental Data).- 12.9 Leader Mechanism of Breakdown of Long Gaps.- 12.10 Return Wave (Return Stroke).- 12.11 Lightning.- 12.12 Negative Stepped Leader.- 13. Capacitively Coupled Radio-Frequency Discharge.- 13.1 Drift Oscillations of Electron Gas.- 13.2 Idealized Model of the Passage of High-Frequency Current Through a Long Plane Gap at Elevated Pressures.- 13.3 V - i Characteristic of Homogeneous Positive Columns.- 13.4 Two Forms of CCRF Discharge Realization and Constant Positive Potential of Space: Experiment.- 13.5 Electrical Processes in a Nonconducting Electrode Layer and the Mechanism of Closing the Circuit Current.- 13.6 Constant Positive Potential of the Weak-Current Discharge Plasma.- 13.7 High-Current Mode.- 13.8 The Structure of a Medium-Pressure Discharge: Results of Numerical Modeling.- 13.9 Normal Current Density in Weak-Current Mode and Limits on the Existence of this Mode.- 14. Discharges in High-Power CW CO2 Lasers.- 14.1 Principles of Operation of Electric-Discharge CO2 Lasers.- 14.2 Two Methods of Heat Removal from Lasers.- 14.3 Methods of Suppressing Instabilities.- 14.4 Organization of Large-Volume Discharges Involving Gas Pumping.- References.

Dye-sensitized Solar Cells

Abstract: The dye-sensitized solar cells (DSC) provides a technically and economically credible alternative concept to present day p–n junction photovoltaic devices. In contrast to the conventional systems where the semiconductor assume both the task of light absorption and charge carrier transport the two functions are separated here. Light is absorbed by a sensitizer, which is anchored to the surface of a wide band semiconductor. Charge separation takes place at the interface via photo-induced electron injection from the dye into the conduction band of the solid. Carriers are transported in the conduction band of the semiconductor to the charge collector. The use of sensitizers having a broad absorption band in conjunction with oxide films of nanocrstalline morphology permits to harvest a large fraction of sunlight. Nearly quantitative conversion of incident photon into electric current is achieved over a large spectral range extending from the UV to the near IR region. Overall solar (standard AM 1.5) to current conversion efficiencies (IPCE) over 10% have been reached. There are good prospects to produce these cells at lower cost than conventional devices. Here we present the current state of the field, discuss new concepts of the dye-sensitized nanocrystalline solar cell (DSC) including heterojunction variants and analyze the perspectives for the future development of the technology.

Thermoelectric Cooling and Power Generation

Abstract: In a typical thermoelectric device, a junction is formed from two different conducting materials, one containing positive charge carriers (holes) and the other negative charge carriers (electrons). When an electric current is passed in the appropriate direction through the junction, both types of charge carriers move away from the junction and convey heat away, thus cooling the junction. Similarly, a heat source at the junction causes carriers to flow away from the junction, making an electrical generator. Such devices have the advantage of containing no moving parts, but low efficiencies have limited their use to specialty applications, such as cooling laser diodes. The principles of thermoelectric devices are reviewed and strategies for increasing the efficiency of novel materials are explored. Improved materials would not only help to cool advanced electronics but could also provide energy benefits in refrigeration and when using waste heat to generate electrical power.

Conversion of spin current into charge current at room temperature: Inverse spin-Hall effect

Abstract: The inverse process of the spin-Hall effect (ISHE), conversion of a spin current into an electric current, was observed at room temperature. A pure spin current was injected into a Pt thin film using spin pumping, and it was observed to generate electromotive force transverse to the spin current. By changing the spin-current polarization direction, the magnitude of this electromotive force varies critically, consistent with the prediction of ISHE.

Tunneling through a controllable vacuum gap

Abstract: We report on the first successful tunneling experiment with an externally and reproducibly adjustable vacuum gap. The observation of vacuum tunneling is established by the exponential dependence of the tunneling resistance on the width of the gap. The experimental setup allows for simultaneous investigation and treatment of the tunnel electrode surfaces.