Increase In Local Electric Field Research Articles

Transverse acousto-electric effect in superconductors

We formulate a theory based on the time-dependent Ginzburg–Landau (TDGL) theory and Newtonian vortex dynamics to study the transverse acousto-electric response of a type-II superconductor with Abrikosov vortex lattice. When exposed to a transverse acoustic wave, Cooper pairs emerge from the moving atomic lattice and moving electrons. As in the Tolman–Stewart effect in a normal metal, an electromagnetic field is radiated from the superconductor. We adapt the equilibrium-based TDGL theory to this non-equilibrium system by using a floating condensation kernel. Due to the interaction between normal and superconducting components, the radiated electric field as a function of magnetic field attains a maximum value occurring below the upper critical magnetic field. This local increase in electric field has weak temperature dependence and is suppressed by the presence of impurities in the superconductor.

Lorentz factor determination for local electric fields in semiconductor devices utilizing hyper-thin dielectrics

The local electric field (the field that distorts, polarizes, and weakens polar molecular bonds in dielectrics) has been investigated for hyper-thin dielectrics. Hyper-thin dielectrics are currently required for advanced semiconductor devices. In the work presented, it is shown that the common practice of using a Lorentz factor of L = 1/3, to describe the local electric field in a dielectric layer, remains valid for hyper-thin dielectrics. However, at the very edge of device structures, a rise in the macroscopic/Maxwell electric field Ediel occurs and this causes a sharp rise in the effective Lorentz factor Leff. At capacitor and transistor edges, Leff is found to increase to a value 2/3 < Leff < 1. The increase in Leff results in a local electric field, at device edge, that is 50%–100% greater than in the bulk of the dielectric. This increase in local electric field serves to weaken polar bonds thus making them more susceptible to breakage by standard Boltzmann and/or current-driven processes. This has important time-dependent dielectric breakdown (TDDB) implications for all electronic devices utilizing polar materials, including GaN devices that suffer from device-edge TDDB.

Modeling and numerical analysis of corona-induced vibration on high-voltage transmission line with raindrops

In rainy days, rainfall hitting high-voltage transmission lines forms raindrops that suspended to lower surface of the conductors. The suspended raindrops subjected to electric field take a cone shape, which leads to a drastic increase in local electric field and amplifies the corona discharge. Electrostatic attractive force between the conductor and the ground is partially shielded by space charge during the corona discharge. Intermittent shielding and the time lags may be the main causes of this phenomenon namely corona-induced vibration. Like any other mechanical oscillations, this kind of vibration may result in fatigue damages of conductors, failures of insulator strings and spacers. This paper is to validate a numerical model based on the finite element method and Newmark algorithm to reveal the formation mechanism of the corona-induced vibrations. According to the numerical model, the effect of rain intensity, electric field and applied voltage on vibration amplitudes and natural frequency are systematically investigated. The results agree well with experimental data available in the literature. The model and numerical analysis method enable a better comprehension of the formation mechanism of the corona-induced vibrations.

Enhancing compressive strength of electrorheological fluid by patterning the electrode

Slip at the interface of solidified electrorheological （ER） fluid and electrodes is harmful for ER applications. Compression tests using four kinds of electrodes, namely the smooth, hole array patterned by laser pulse, nylon net covered, and acid etched column patterned electrodes, have been done, respectively. Results show that laser patterned and nylon net covered electrodes significantly enhanced the compressive stress of the ER fluid. The enhancement is ascribed to the increase of local electric field near electrodes after patterning, which increased the interfacial strength between ER fluid and electrodes, and effectively suppressed the slip of solidified ER fluid from electrode. The tests of current density during compression and the finite element analysis of the electric field distribution of patterned electrodes supported this slip suppression effect. The results raised a fundamental question of what is the real strength of ER fluids, since the slip of highly solidified ER fluid are usually not considered during various tests. This investigation also shows that patterning electrodes is a good way to improve mechanical performances of ER fluids.

Field Electron Emission from Carbon Nanotube Films on Diamond Films

The field electron emission from carbon nanotube films on polycrystalline diamond films was investigated. The carbon nanotubes and diamond films on Si substrates were prepared by a conventional hot filament chemical vapour deposition. The films obtained were characterized by scanning electron microscopy and Raman spectroscopy. The field emission properties of the samples were measured in an ion-pumped vacuum chamber at a pressure of 10-6 Pa.. The experimental results showed that the field emission behaviours of carbon nanotubes/diomond films structure have greatly been improved as compared with carbon nanotubes and diamond films, respectively. A turn-on field of 1.0 V/µm and a maximum current of 500 µA at 1.5 V/µm were observed, which were lower than those of carbon nanotubes and polycrystalline diamond films, respectively. This improvement was attributed to the tip shape of sample surface, which provided an additional local increase in electric field at the tube ends.

Electric field induced deformation of the CDW condensate in the sliding mode

The Tua-Zawadowski model is used to show that the field induced deformation of sliding CDW around the impurity results in an increase in local electric field and a decrease in effective impurity pinning force.