Composite Pulses in Inhomogeneous Field NMR

2013 ◽  
pp. 137-147
Author(s):  
Galina S. Kupriyanova ◽  
Vitaliy V. Molchanov ◽  
Evgeniy A. Severin ◽  
Ivan G. Mershiev
Keyword(s):  
Inhomogeneous Field ◽  
Composite Pulses

SIMULATION OF THE FLIGHT OF A DROP OF GALVANIC ELECTROLYTE IN AN INHOMOGENEOUS FIELD OF AN ELECTRIC CATCHER

2020 ◽  
Author(s):  
V.I. Garshin ◽  
◽  
A.R. Lebedev ◽  
S.E. Geraskova ◽  
◽  
...  
Keyword(s):  
Electric Field ◽  
Flight Path ◽  
Inhomogeneous Field ◽  
Inhomogeneous Electric Field ◽  
Trajectory Method

The article shows the relations for modeling an inhomogeneous electric field and the flight path of a drop of galvanic electrolyte in it. Estimates are preliminary. Articles and patents of authors in which non-uniform fields are already used are given. A modified trajectory method is proposed for evaluating the effectiveness of trapping harmful electrolyte droplets.

scholarly journals Active, Reactive, and Apparent Power in Dielectrophoresis: Force Corrections from the Capacitive Charging Work on Suspensions Described by Maxwell-Wagner’s Mixing Equation

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 738
Author(s):  
Jan Gimsa
Keyword(s):  
Volume Fraction ◽  
Inhomogeneous Field ◽  
Effective Polarizability ◽  
Polarization Mechanism ◽  
Free Transition ◽  
Lossy Media ◽  
New Perspective ◽  
A Chain ◽  
A Charge ◽  
Induced Changes

A new expression for the dielectrophoresis (DEP) force is derived from the electrical work in a charge-cycle model that allows the field-free transition of a single object between the centers of two adjacent cubic volumes in an inhomogeneous field. The charging work for the capacities of the volumes is calculated in the absence and in the presence of the object using the external permittivity and Maxwell-Wagner’s mixing equation, respectively. The model provides additional terms for the Clausius-Mossotti factor, which vanish for the mathematical boundary transition toward zero volume fraction, but which can be interesting for narrow microfluidic systems. The comparison with the classical solution provides a new perspective on the notorious problem of electrostatic modeling of AC electrokinetic effects in lossy media and gives insight into the relationships between active, reactive, and apparent power in DEP force generation. DEP moves more highly polarizable media to locations with a higher field, making a DEP-related increase in the overall polarizability of suspensions intuitive. Calculations of the passage of single objects through a chain of cubic volumes show increased overall effective polarizability in the system for both positive and negative DEP. Therefore, it is proposed that DEP be considered a conditioned polarization mechanism, even if it is slow with respect to the field oscillation. The DEP-induced changes in permittivity and conductivity describe the increase in the overall energy dissipation in the DEP systems consistent with the law of maximum entropy production. Thermodynamics can help explain DEP accumulation of small objects below the limits of Brownian motion.

Dielectric Strength of Liquid Helium under Strongly Inhomogeneous Field Conditions

1960 ◽  
pp. 95-101 ◽  
Author(s):  
M. M. Menon ◽  
S. W. Schwenterly ◽  
W. F. Gauster ◽  
R. H. Kernohan ◽  
H. M. Long
Keyword(s):  
Liquid Helium ◽  
Dielectric Strength ◽  
Field Conditions ◽  
Inhomogeneous Field

scholarly journals Thermal Robustness of Entanglement in a Dissipative Two-Dimensional Spin System in an Inhomogeneous Magnetic Field

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 1066
Author(s):  
Gehad Sadiek ◽  
Samaher Almalki
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Nearest Neighbor ◽  
Quantum Phase Transitions ◽  
Inhomogeneous Magnetic Field ◽  
Steady States ◽  
Inhomogeneous Field ◽  
Spin States ◽  
Two Dimensional ◽  
Spin Lattice

Recently new novel magnetic phases were shown to exist in the asymptotic steady states of spin systems coupled to dissipative environments at zero temperature. Tuning the different system parameters led to quantum phase transitions among those states. We study, here, a finite two-dimensional Heisenberg triangular spin lattice coupled to a dissipative Markovian Lindblad environment at finite temperature. We show how applying an inhomogeneous magnetic field to the system at different degrees of anisotropy may significantly affect the spin states, and the entanglement properties and distribution among the spins in the asymptotic steady state of the system. In particular, applying an inhomogeneous field with an inward (growing) gradient toward the central spin is found to considerably enhance the nearest neighbor entanglement and its robustness against the thermal dissipative decay effect in the completely anisotropic (Ising) system, whereas the beyond nearest neighbor ones vanish entirely. The spins of the system in this case reach different steady states depending on their positions in the lattice. However, the inhomogeneity of the field shows no effect on the entanglement in the completely isotropic (XXX) system, which vanishes asymptotically under any system configuration and the spins relax to a separable (disentangled) steady state with all the spins reaching a common spin state. Interestingly, applying the same field to a partially anisotropic (XYZ) system does not just enhance the nearest neighbor entanglements and their thermal robustness but all the long-range ones as well, while the spins relax asymptotically to very distinguished spin states, which is a sign of a critical behavior taking place at this combination of system anisotropy and field inhomogeneity.

Intensity enhancement of attosecond XUV pulse by using asymmetric inhomogeneous mid-infrared down-chirped field

2017 ◽  
Vol 31 (26) ◽  
pp. 1750185 ◽  
Author(s):  
Liqiang Feng ◽  
Wenliang Li ◽  
Hang Liu
Keyword(s):  
Laser Intensity ◽  
Temporal Frequency ◽  
Three Dimensional ◽  
Pulse Generation ◽  
Homogeneous Field ◽  
Inhomogeneous Field ◽  
Plasmonic Enhancement ◽  
Positive Direction ◽  
Chirped Pulse ◽  
Intensity Enhancement

Intensity enhancement of the attosecond pulse generation from the high-order harmonic spectra has been theoretically investigated through solving the three-dimensional time-dependent Schrödinger equation. It is found that with the introduction of the down-chirped pulse, the temporal frequency of the down-chirp region is decreased. As a result, the ionized electrons can receive much more energy during its acceleration in this region, showing the extension of the harmonic cutoff. Moreover, due to the multi-harmonic emission events contribute to the higher harmonics, the intensity of the harmonic cutoff from the down-chirped pulse is 1.5 orders of magnitude higher than those from the chirp-free pulse. Further, by properly introducing the asymmetric inhomogeneous effect, the plasmonic enhancement of the laser intensity in the negative direction is larger than that in the positive direction. As a consequence, the ionized electron from the down-chirp region with the negative amplitude can obtain the additional acceleration, thus leading to the further extension of the harmonic cutoff. Especially when the spatial position of the inhomogeneous field is chosen to be the negative value, due to the improved enhancement of the laser intensity, not only the harmonic cutoff is extended but also the harmonic yield is near-stable, showing a 175 eV supercontinuum with the single short quantum path contribution. Finally, by directly superposing the selected harmonics, three attosecond XUV pulses with the full widths at half maximum of 38, 35 and 36 as can be obtained, which are nearly 1.5 orders of magnitude enhancement compared with the chirp-free homogeneous field case.

Effect of multiple rescattering processes on harmonic emission in spatially inhomogeneous field

2018 ◽  
Vol 27 (3) ◽  
pp. 034206 ◽  
Author(s):  
Cai-Ping Zhang ◽  
Chang-Long Xia ◽  
Xiang-Fu Jia ◽  
Xiang-Yang Miao
Keyword(s):  
Inhomogeneous Field ◽  
Harmonic Emission ◽  
Spatially Inhomogeneous

Generation of Short-scale Electrostatic Fields in the Solar Atmosphere and the Role of Helium Ions

2021 ◽  
Vol 922 (1) ◽  
pp. 48
Author(s):  
H. Saleem ◽  
Shaukat Ali Shan ◽  
A. Rehman
Keyword(s):  
Shear Flow ◽  
Transition Region ◽  
Electric Fields ◽  
Hydrogen Plasma ◽  
Theoretical Models ◽  
Inhomogeneous Field ◽  
Helium Ions ◽  
Low Frequencies ◽  
Short Scale

Abstract Theoretical models are presented to show that expansion of plasma in the radial direction from a denser solar surface to a rarefied upper atmosphere with short-scale inhomogeneous field-aligned flows and currents in the form of thin threads itself is an important source of electrostatic instabilities. Multifluid theory shows that the shear flow–driven purely growing electric fields appear in the transition region. On the other hand, plasma kinetic theory predicts that the short-scale current sheets (or filaments) produce current-driven electrostatic ion acoustic (CDEIA) waves in the hydrogen plasma of the transition region that damp out in the system through wave–particle interactions and increase the temperature. Similar processes take place in the solar corona and act positively for increasing the temperature further and maintaining it. The shear flow–driven instabilities and CDEIA waves have short perpendicular wavelengths of the order of 1 m and low frequencies of the order of 1 or several Hz when the ions’ shear flow scale length is considered to be of the order of 1 km. It is pointed out that the purely growing fluid instabilities turn into oscillatory instabilities and the growth rates of kinetic CDEIA wave instabilities are reduced when the dynamics of 10% helium ions is taken into account along with 90% hydrogen ions. Therefore, the role of helium ions should not be ignored in the study of wave dynamics in solar plasma.

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