Search results for "electric field"
showing 10 items of 545 documents
Charged colloidal particles in a charged wedge: do they go in or out?
2008
Using real-space microscopy experiments, theory and computer simulation, we study the behaviour of highly charged colloidal particles which are confined between two highly charged plates forming a wedge geometry. Under low salt conditions it is experimentally observed that colloidal particles accumulate in the cusp of a wedge to form dense fluid or crystalline ordered structures. This behaviour is found for various cell geometries, salt concentrations and gravitational strengths, and even stays stable when additional convection is present in the system. An effort is made to understand this effect qualitatively on the basis of linear screening theory. For a single macro-ion, linear screening…
Modeling X-ray emission from stellar coronae
2008
By extrapolating from observationally derived surface magnetograms of low-mass stars we construct models of their coronal magnetic fields and compare the 3D field geometry with axial multipoles. AB Dor, which has a radiative core, has a very complex field, whereas V374 Peg, which is completely convective, has a simple dipolar field. We calculate global X-ray emission measures assuming that the plasma trapped along the coronal loops is in hydrostatic equilibrium and compare the differences between assuming isothermal coronae, or by considering a loop temperature profiles. Our preliminary results suggest that the non-isothermal model works well for the complex field of AB Dor, but not for the…
Electro-optic dynamics in thermally poled Ge core doped silica fibre
2003
The electro-optic (EO) dynamics of a twin hole germania core doped fibre when an applied electric field at elevated temperature modifies the symmetry of glass is reported. An EO peak was recorded after 10 min poling. The results were interpreted with a two-space charge model.
The route to high accuracy in ab initio calculations of Cu quadrupole-coupling constants.
2012
We report nonrelativistic and scalar-relativistic coupled-cluster calculations of the copper quadrupole-coupling constants for eleven small copper-containing compounds. It is shown to be necessary to treat both electron-correlation and scalar-relativistic effects on the same footing even for a qualitatively correct description, because both effects are significant and are strongly coupled in the case of Cu electric-field gradients. We show that the three scalar-relativistic schemes employed in the present study--the leading order of direct perturbation theory, the spin-free exact two-component theory in its one-electron variant, and the spin-free Dirac-Coulomb approach--provide accurate tre…
Electromagnetic Full-Wave Simulation of Partial Discharge Detection in High Voltage AC Cables
2019
Partial discharge (PD) activity in the insulation system of an electrical equipment can determine the failure of the whole apparatus. PD sensors are widely used in high-voltage electrical systems as the main elements of a detecting system oriented to real time monitoring. Recently, non-invasive sensors have been proposed in industrial applications for cable and other sensitive electrical parts: they are based both on capacitive and on the electromagnetic radiating coupling. In order to assess the real performance of a new sensor produced by a high voltage AC cables manufacturer, the paper proposes electromagnetic fullwave simulation results.
Absence of structure in the $^{20,22}$Ne + $^{118}$Sn quasi-elastic barrier distribution
2005
Abstract Motivated by the extreme deformation parameters of the projectile, we have measured quasi-elastic scattering for 20 Ne + 118 Sn. In contrast to calculations based on known collective states, the experimental barrier distribution is structureless. A comparison with the system 22 Ne + 118 Sn shows that this smoothing is unlikely to be due to nucleon- or α -transfer channels, and is more likely to be due to coupling to many other weak channels.
Spin-orbit, radial, and angular coupling effects in the NaRb excited states
2009
Spin-orbit, radial, and angular nonadiabatic matrix elements between the lowest excited states of NaRb are evaluated by quasi-relativistic ab initio methods, and the results accompanied by potential curves, permanent and transition moments are compared with experimental data and preceding calculations.
Interpretation of Mössbauer Parameters of Iron Compounds
1978
The task of this section is to show that for the interpretation of Mossbauer parameters — in the present case of electron densities, field gradients and magnetic hyperfine fields — bonding effects can play an important role, and free-ion or crystal field approaches may be a poor approximation.
Crystal Electric Fields in Rare-Earth Al2 Compounds
1977
Neutron time-of-flight measurements have been performed on REAl2 compounds (RE = Pr, Ho, Er, Tm) in the paramagnetic region. Resolved crystal field transitions are observed in ErAl2 and TmAl2. We deduce crystal field parameters (x = 0.16, W = -0.030 meV) and (x = -0.28, W = +0.040 meV) for ErAl2 and TmAl2 respectively.
Peculiarity of Low Density Plasma-Assisted Charge Emission Produced at LATGS Crystal Surface
2011
Time and energy distribution measurements for a weak plasma-assisted electron and ion emission, initiated at the surface of L-α alanine doped TGS (LATGS) single crystals by a drive ac (500 Hz) electric field exceeding 5 × 103 V/cm, have been performed especially at temperatures below as well as above phase transition. Time spectra of charges obtained at temperatures below phase transition are considerably different than that detected above phase transition; total number of charges registered under switching conditions is about an order higher than that produced during mere charging of the sample; time dependent energy spectra involve charges (electrons and ions) with energies up to a few hu…