The Influence of Humidity on Electron Transport Parameters and Insulation Performance of Air

The environmental conditions affect the external insulation performance of power equipment. In order to study the physical characteristics of air discharge, the microscopic process of electron–molecule collision in the air based on the Boltzmann equation has been studied in this paper. The influence of humidity on the air gap insulation performance was also analyzed. The calculation results show that with the temperature 300 K and the pressure 1.0 atm, the electron energy distribution function and electron transport parameters varied with the air relative humidity. As the air relative humidity is increased by each 30%, the average electron energy decreases by about 0.2 eV, the reduced electron mobility decreases by about 0.25 × 1023 [1/(V·m·s)], the reduced electron diffusion coefficient decreases by about 0.2 × 1024 [1/(m s)], and the effective ionization coefficient decreases by about 4 × 10−24 m2. As the air relative humidity increases from 0% to 60%, the critical breakdown electric field increases by 1.22 kV/cm.

Electron swarm parameters and dielectric strength of C5F10O and its mixtures with CO2 and dry air

Perfluoroketone C5F10O is considered as a potential SF6 alternative. The GWP (Global warming potential) of C5F10O is extremely low and even close to that of air. We investigated the electrical insulation properties of the C5F10O by pulsed Townsend (PT) experiment. The rate coefficients of ionization, attachment, and effective ionization, as well as the electron drift velocity and the longitudinal electron diffusion coefficient in pure C5F10O were obtained. We conclude that the density-reduced critical electric field of pure C5F10O is (768±5)Td and ion kinetics are not exist or negligible in C5F10O. Furthermore, the swarm parameters of C5F10O /CO2 and C5F10O /Air mixtures with C5F10O percentage up to 30% were measured in a wide E/N-range. C5F10O has good synergism with both CO2 and dry air and air behaves better. The synergistic effect coefficients were also calculated. To have the same (E/N)crit as pure SF6, the mixing ratio of C5F10O should be 30% in the mixture with CO2 and 26% in the mixture with dry air. The obtained electron swarm parameters in this paper provide a supplement for the fundamental data set of these novel gases, and also lay the foundation for fluid model simulations of gas discharge.

Temperature dependence of carbon nanoparticles transport characteristics

Technique for calculating the temperature dependences of transport characteristics of different carbon nanoparticles: single-walled nanotubes, graphene, bilayer graphene in a constant external electric field is proposed. Formulas for conductivity and the diffusion coefficient of electrons in carbon nanostructures obtained analytically and analyzed numerically. Conductivity in single-walled and bilayer carbon nanostructures decreases with increasing temperature. The electrical conductivity of carbon nanoparticles depends nonlinearly on the amplitude of the external constant electric field for various temperatures. With increasing temperature, the coefficient of conductivity decreases. The diffusion coefficient of electrons is independent of temperature for both single-layer and bilayer nanoparticles. A nonlinear dependence of the electron diffusion coefficient on the strength of an external constant electric field is shown. Physical justification of the obtained dependences is propose.

NUMERICAL CALCULATIONS OF THE ELECTRON ENERGY DISTRIBUTION FUNCTION IN (50% SF6 - 50 % Xe) MIXTURE WITH CORRESPONDING TRANSPORT PARAMETERS

We used EEDF software package program to solve Boltzmann equation to calculate the electron energy distribution function in (50% SF6 – 50% Xe) mixture. The calculations are achieved under a steady state electric field using the classical two - term approximation. The electron energy distribution function (EEDF) and the corresponding transport coefficients (mean electron energy, characteristic energy, mobility of electron, diffusion coefficient, and drift velocity) for constant and various electron concentrations are calculated and graphically represented. It is found that variations of electron concentration have a significant effect on transport coefficients of the mixture. The work is in a well agreement with previously experimental and computational researches.

Electrical conductivity and Einstein relation modeling in phosphorene

Investigation on (2-dimensional) (2D) materials is growing significantly due to the fundamental electronic properties in the direct inherent bandgap, higher carrier mobility, and easier exfoliation. Phosphorene as a new 2D configuration has presented excellent potential in electronic and optoelectronic applications. In this study, the conductivity of monolayer phosphorene and Einstein’s relations as fundamental parameters in semiconductor manufacturing are analytically modeled. In addition, dependency of conductivity on normalized Fermi energy ([Formula: see text]) is demonstrated. According to the simulation results, conductivity and Einstein’s relation are completely dependent on temperature, therefore, rising up the temperature leads to conductivity and diffusion coefficient (Dn) growth. Indeed, conductivity is saturated when the normalized Fermi energy exceeds than 6. Also, the conductivity and Einstein’s relation dependency to voltage are studied. Results show that carrier conductivity and the electron diffusion coefficient (Dn) increase by amplifying the voltage.

Understanding and removing surface states limiting charge transport in TiO2 nanowire arrays for enhanced optoelectronic device performance

An effective wet-chemistry approach is demonstrated to minimize the trap states that limit electron transport in rutile TiO2 nanowire arrays, this leads to an over 20-fold enhancement in the electron diffusion coefficient.

Identifying effects of TiO2 nanowires inside bulk heterojunction organic photovoltaics on charge diffusion and recombination

The effect of incorporating TiO2 nanowires into organic photovoltaics has been studied using impedance spectroscopy. Electron diffusion coefficient and effective lifetime in different devices were simulated and compared.