Higher-order Charge Research Articles

Two-dimensional vortex dipole solitons in nonlocal nonlinearity with PT-symmetric Scarff-II potential.

We investigate the dynamics and stability of two-dimensional (2D) vortex dipole solitons in nonlocal nonlinearity with PT-symmetric Scarff-II potential. We analyze the solitons with single charge and higher-order charge using analytical and numerical methods. By the variational approach, we can obtain analytical solutions for the model. It is found that the nonlocality degree affects the evolution of the beams. We discover that the vortex dipole solitons will undergo stable deformation rather than maintaining their basic profile when the nonlocality is strong. Moreover, the stability of the vortex dipole solitons depends on the potential depth and there exists a threshold, below which the beams can keep their shapes and propagate stably whether the nonlocality is weak, intermediate, or strong. Numerical simulations are consistent with the analytical results.

Multiply charged ion emission from laser produced tungsten plasma

AbstractPlasma was generated by focusing 10 ns Nd:YAG (λ = 1064 nm) laser pulse on the thick tungsten target. The laser fluence at the target was varied in the range of 3.57–10.97 J/cm2. The ion emission from the expanding tungsten plasma was analyzed with the help of an ion collector and time-of-flight electrostatic ion energy analyzer. About 44 times rise in the ion charge per laser shot was observed in the investigated laser fluence range. The measured threshold fluence for onset of the tungsten plasma was 3.27 J/cm2. The estimated plume expansion coefficient Zinf/Xinf = 2.5 ± 0.2 was in agreement with the previous experimental studies and the predictions of self-similar plume expansion model. The electrostatic ion energy analyzer study showed that charge state of the W ions increases with the laser fluence and maximum ion charge state was 5+. It was observed that threshold fluence for appearance of a specific charge state can be measured. A clear correlation between the relative abundances of W(n−1)+, Wn+, and W(n+1)+ indicates that higher order charge states are most probably produced by stepwise ionization process.

Universal correlations in pion-less EFT with the resonating group method: Three and four nucleons

The Effective Field Theory “without pions” at next-to-leading order is used to analyze universal bound-state and scattering properties of the 3- and 4-nucleon system. Results of a variety of phase shift equivalent nuclear potentials are presented for bound-state properties of 3H and 4He , and for the singlet S -wave 3He -neutron scattering length a 0(3He-n) . The calculations are performed with the Refined Resonating Group Method and include a full treatment of the Coulomb interaction and the leading-order 3-nucleon interaction. The results compare favorably with data and values from AV18(+UIX) model calculations. A new correlation between a 0(3He-n) and the 3H binding energy is found. Furthermore, we confirm at next-to-leading order the correlations, already found at leading order, between the 3H binding energy and the 3H charge radius, and the Tjon line. With the 3H binding energy as input, we get predictions of the effective field theory “without pions” at next-to-leading order for the root mean square charge radius of 3H of (1.6±0.2) fm, for the 4He binding energy of (28±2.5) MeV, and for Re{a 0(3He-n)} of (7.5±0.6) fm. Including the Coulomb interaction, the splitting in binding energy between 3H and 3He is found to be (0.66±0.03) MeV. The discrepancy to data of (0.10±0.03) MeV is model independently attributed to higher-order charge independence breaking interactions. We also demonstrate that different results for the same observable stem from higher-order effects, and carefully assess that numerical uncertainties are negligible. Our results demonstrate the convergence and usefulness of the pion-less theory at next-to-leading order in the 4He channel. We conclude that no 4-nucleon interaction is needed to renormalize the theory at next-to-leading order in the 4-nucleon sector.

Technology-Independent Non-Quasi-Static Table-Based Nonlinear Model Generation

An analytical extraction of the non-quasi-static nonlinear lookup table FET model at mm-wave frequencies is demonstrated in this study. Frequency dispersion present at mm-wave frequencies is compensated for by introduction of higher order dynamics of nonlinear constituent components. Nonlinear charge- and current-sources are used as the constituent components to represent the nonlinear device where the higher order charge- and current-sources are introduced to compensate for the non-quasi-static effects. The presented approach is validated using SOI Multi-Fin MOSFET transistors, the multiple gate MOSFET structures which have been introduced as an alternative candidate for bulk planar CMOS technology in the nanometer regime. An accurate multibias linear model is employed as the keystone for building the non-quasi-static nonlinear model. Large-signal measurements are used for model validation. Significant improvements are observed over the quasi-static nonlinear model which is demonstrated by excellent agreement between measurements and nonlinear model presented here.

Two-photon absorption and fluorescence in nanoscale multipolar chromophores: effect of dimensionality and charge-symmetry

A series of structurally related chromophores of different symmetry (quadrupolar, C 2 v , octupolar,…) and shape (rod-like, propeller-shaped, Y-shaped, dendritic,…) were investigated and compared for optimization of molecular two-photon absorption (TPA). Their design is based on the functionalization of linear or branched conjugated backbones with electron-releasing and/or electron-withdrawing peripheral groups. Their TPA spectra were determined by investigating their two-photon-excited fluorescence properties in the NIR region using pulsed excitation in the femtosecond regime. These studies provide evidence that the charge symmetry plays an important role in determining the TPA magnitude, the quadrupolar chromophore leading to the highest TPA cross-section. However, higher-order charge symmetries and branched structures provide an interesting route for improvement of the non-linear absorptivity/transparency range trade-off as well as for TPA spectral broadening in the NIR region.

Analytical expressions of potential and electric field generated by a triangular surface charge with a high‐order charge density distribution

AbstractWe have derived analytical expressions of the potential and electric field generated by a triangular surface charge that has a second‐ or third‐order charge density distribution on each element. These expressions are applicable to the surface charge method (SCM) for calculating electric field in three‐dimensional arrangements. In general, the higher‐order charge density expression improves the accuracy of the SCM. Moreover, the SCM with analytical expressions needs no troublesome treatment of singular points inevitably involved in the SCM using numerical integration. We have also confirmed the validity of these derived analytical expressions by comparing the calculated results with those by the numerical method. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(3): 9–17, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.1155

Evidence for spinodal decomposition in nuclear multifragmentation.

Multifragmentation of a "fused system" was observed for central collisions between 32 MeV/nucleon 129Xe and (nat)Sn. Most of the resulting charged products were well identified due to the high performances of the INDRA 4pi array. Experimental higher-order charge correlations for fragments show a weak but nonambiguous enhancement of events with nearly equal-sized fragments. Supported by dynamical calculations in which spinodal decomposition is simulated, this observed enhancement is interpreted as a "fossil" signal of spinodal instabilities in finite nuclear systems.

The specific heat of NdNi/sub 5/

The specific heat of NdNi/sub 5/ measured on a single-crystalline specimen from 1.5 K to 250 K has been analyzed in terms of two electronic subsystems, i.e. conduction-electron and f-electron subsystems. The conduction-electron subsystem is found in LaNi/sub 5/ to be characterized by a value of the Sommerfeld coefficient /spl gamma/ of 36 mJ/K/sup 2/mol f.u. The contribution of the f-electron subsystem to the specific heat shows a /spl lambda/-type of peak at T/sub c/ of 7.4 K and a non-pronounced Schottky-type of peak above T/sub c/. The f contribution is well described within a single-ion Hamiltonian that includes the crystalline-electric-field (CEF) and exchange interactions of the Nd/sup 3+/ ions. The exchange parameter and the full set of the CEF parameters associated with the hexagonal symmetry have been evaluated. The ground state /spl Gammasub 8/ for the Nd/sup 3+/ ion in NdNi/sub 5/ is highly anisotropic with the magnetic moment lying within the hexagonal plane. This ground-state results from higher-order charge multipolar interactions. >

SPECIFIC HEAT OF UPd2Al3

Particularities in the specific heat of UPd 2 Al 3, a λ-type of peak with a maximum at 14.5 K and a Schottky-type of peak with a broad maximum at 55 K, has been attributed to the 5f-subsystem of the U atoms. The U-5f contribution has been found to be described surprisingly well within a single-ion Hamiltonian that includes the charge multipolar (CMP) interactions and the antiferromagnetic (AF) exchange interaction between the U 3+ ions. The AF exchange parameter and the full set of the CMP parameters associated with the hexagonal symmetry have been evaluated. The energy-level scheme (ELS) of this Kramers ion is constructed. The ground-state function Γ8 of the 5f 3 electrons is highly anisotropic. This state results from higher-order charge multipolar interactions. Magnetic properties resulting from this scheme including the metamagnetic-like transition at 18 T, the strongly-reduced value for the U-ion moment and its field dependence are found to be in good agreement with experimental observations.