Log in

Relevant bibliographies by topics / Time-harmonic field / Journal articles

Journal articles on the topic 'Time-harmonic field'

To see the other types of publications on this topic, follow the link: Time-harmonic field.

Author: Grafiati

Published: 10 March 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Time-harmonic field.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Faul, Fabian T., Jonas Kornprobst, Torsten Fritzel, Hans-Jürgen Steiner, Rüdiger Strauß, Alexander Weiß, Robert Geise, and Thomas F. Eibert. "Near-field measurement of continuously modulated fields employing the time-harmonic near- to far-field transformation." Advances in Radio Science 17 (September 19, 2019): 83–89. http://dx.doi.org/10.5194/ars-17-83-2019.

Full text

Abstract:

Abstract. Near-field far-field transformations (NFFFTs) are commonly performed for time-harmonic fields. Considering arbitrary in-situ measurement scenarios with given transmission signals, time-varying aspects of modulated signals have to be taken into consideration. We investigate and characterize two methods for the measurement of modulated fields, which work with a time-domain representation of the radiated fields and, at the same time, allow to employ the standard time-harmonic NFFFT. One method is based on the fact that the modulation signal can be assumed to be constant in a short enough measurement interval under the condition that the modulation and carrier frequencies are several decades apart. The second method performs long-time measurements in order to obtain the complete frequency spectrum in every single measurement. Both methods are verified by the NFFFT of synthetic field data.

APA, Harvard, Vancouver, ISO, and other styles

2

Banchs, R. E., and F. X. Bostick. "Time-harmonic field analysis of electric logging systems." IEEE Transactions on Geoscience and Remote Sensing 40, no. 6 (June 2002): 1427–30. http://dx.doi.org/10.1109/tgrs.2002.800752.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Gralak, Boris, and Daniel Maystre. "Negative index materials and time-harmonic electromagnetic field." Comptes Rendus Physique 13, no. 8 (October 2012): 786–99. http://dx.doi.org/10.1016/j.crhy.2012.04.003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Qian, S. W., Y. T. Hu, and J. S. Wang. "Time-dependent harmonic oscillators in an electromagnetic field." Journal of Physics A: Mathematical and General 20, no. 10 (July 11, 1987): 2833–41. http://dx.doi.org/10.1088/0305-4470/20/10/027.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Yüce, Cem. "Exact solution of the time-dependent harmonic plus an inverse harmonic potential with a time-dependent electromagnetic field." Annals of Physics 308, no. 2 (December 2003): 599–604. http://dx.doi.org/10.1016/s0003-4916(03)00175-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Schaller, Richard D., Justin C. Johnson, and Richard J. Saykally. "Time-Resolved Second Harmonic Generation Near-Field Scanning Optical Microscopy." ChemPhysChem 4, no. 11 (November 6, 2003): 1243–47. http://dx.doi.org/10.1002/cphc.200300907.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Liu, Wensen, and Jisuo Wang. "Time evolution of a time-dependent harmonic oscillator in a static magnetic field." Journal of Physics A: Mathematical and Theoretical 40, no. 5 (January 17, 2007): 1057–63. http://dx.doi.org/10.1088/1751-8113/40/5/013.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Gold, Alysson, and Sami Tantawi. "A Classical Field Theory Formulation for the Numerical Solution of Time Harmonic Electromagnetic Fields." IEEE Journal on Multiscale and Multiphysics Computational Techniques 4 (2019): 245–59. http://dx.doi.org/10.1109/jmmct.2019.2950555.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

QIAO, H. X., Y. C. ZOU, and Z. J. ZHANG. "HIGH-ORDER HARMONIC GENERATION OF HYDROGEN IN INTENSE LASER FIELD AND STRONG MAGNETIC FIELD." International Journal of Modern Physics C 15, no. 04 (May 2004): 493–506. http://dx.doi.org/10.1142/s0129183104005899.

Full text

Abstract:

An effective one-dimensional model approach combining time-dependent pseudospectral method and Taylor expansion [Haoxue Qiao et al., Phys. Rev. A65, 063403 (2002)] is generalized to study a real hydrogen atom in an intense laser field. High-order harmonic generations are calculated in several cases of different laser field parameters. The ionization probability is also calculated. The influence of the strong magnetic field on harmonic generations is investigated. It is found that the plateau of high harmonics can be extended by the magnetic field and the cutoff order increases with the increase of the field intensity.

APA, Harvard, Vancouver, ISO, and other styles

10

PINTO, TIAGO, and JEAN-PIERRE COYETTE. "CONJUGATED INFINITE ELEMENTS FOR TWO-DIMENSIONAL TIME-HARMONIC ELASTODYNAMICS." Journal of Computational Acoustics 08, no. 03 (September 2000): 473–93. http://dx.doi.org/10.1142/s0218396x00000327.

Full text

Abstract:

Wave propagation problems in unbounded domains require the handling of appropriate radiation conditions (Sommerfeld). Various absorbing boundary conditions are available for that purpose. In a discrete finite element context, local and global Dirichlet-to-Neumann (DtN) and infinite element methods have shown their efficiency for the scalar wave equation. The paper concentrates on the extension of an infinite element method to the elastodynamic vector wave equation. The extension is developed in the frequency domain for 2-D problems. The paper focuses on the development of a conjugated formulation using the Helmholtz decomposition theorem of smooth vector fields. The accuracy of the developed formulation is assessed through the study of benchmarks. The computed results are shown to be in good agreement with the analytical solution for a multi-pole field along a circular cavity and with the results produced by other numerical methods.

APA, Harvard, Vancouver, ISO, and other styles

11

Jansari, Chintan, Javier Videla, Sundararajan Natarajan, Stéphane P. A. Bordas, and Elena Atroshchenko. "Adaptive enriched geometry independent field approximation for 2D time-harmonic acoustics." Computers & Structures 263 (April 2022): 106728. http://dx.doi.org/10.1016/j.compstruc.2021.106728.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Marticorena Garcia, Stephan Rodrigo, Markus Grossmann, Sophia Theresa Lang, Manh Nguyen Trong, Michael Schultz, Jing Guo, Bernd Hamm, Jürgen Braun, Ingolf Sack, and Heiko Tzschätzsch. "Full-Field-of-View Time-Harmonic Elastography of the Native Kidney." Ultrasound in Medicine & Biology 44, no. 5 (May 2018): 949–54. http://dx.doi.org/10.1016/j.ultrasmedbio.2018.01.007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Gąsiorski, A. K. "Non-symmetrical shaped conductors located in a time-harmonic TM field." Archiv für Elektrotechnik 69, no. 1 (January 1986): 1–9. http://dx.doi.org/10.1007/bf01573975.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Ateş, Ülkü Dinlemez. "Properties of the far field operator for time harmonic acoustic waves." Applied Mathematics and Computation 174, no. 2 (March 2006): 1206–15. http://dx.doi.org/10.1016/j.amc.2005.06.008.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Fernandez-Corbaton, Ivan. "A Conformally Invariant Derivation of Average Electromagnetic Helicity." Symmetry 11, no. 11 (November 19, 2019): 1427. http://dx.doi.org/10.3390/sym11111427.

Full text

Abstract:

The average helicity of a given electromagnetic field measures the difference between the number of left- and right-handed photons contained in the field. Here, the average helicity is derived using the conformally invariant inner product for Maxwell fields. Several equivalent integral expressions in momentum space, in ( r , t ) space, and in the time-harmonic ( r , ω ) space are obtained, featuring Riemann–Silberstein-like fields and potentials. The time-harmonic expressions can be directly evaluated using the outputs of common numerical solvers of Maxwell equations. The results are shown to be equivalent to the well-known volume integral for the average helicity, featuring the electric and magnetic fields and potentials.

APA, Harvard, Vancouver, ISO, and other styles

16

Wang, Yunhui, Dandan Song, Qiang Zuo, Hong Wu, and Zhihong Yang. "High-order harmonic generation with a single-color mid-infrared laser field by frequency-chirping." International Journal of Modern Physics B 33, no. 13 (May 20, 2019): 1950122. http://dx.doi.org/10.1142/s0217979219501224.

Full text

Abstract:

By numerically solving the time-dependent Schrödinger equation for helium atoms in a single mid-infrared laser field, we explore the frequency-chirping effect of laser field on high-order harmonic and isolated attosecond pulse generation. One or two ultrabroad supercontinuum harmonic plateaus can be controlled through modulating the laser field frequency by a small time-dependent signal. Under the best chirping condition, an ultrashort 2.2 as pulse can be obtained by Fourier transformation with the bandwidth of 782 eV. Furthermore, we explain the harmonic generation physical mechanisms by classical ionizing and returning energy maps and time–frequency analyzes.

APA, Harvard, Vancouver, ISO, and other styles

17

Tinkelman, Igor, and Timor Melamed. "Local spectrum analysis of field propagation in an anisotropic medium Part I Time-harmonic fields." Journal of the Optical Society of America A 22, no. 6 (June 1, 2005): 1200. http://dx.doi.org/10.1364/josaa.22.001200.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Cai, Li Ming, Hui Qi, and Xiang Nan Pan. "The Scattering of Circular Cylindrical Cavity with Time-Harmonic SH Waves in Infinite Strip Region." Applied Mechanics and Materials 580-583 (July 2014): 3083–88. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.3083.

Full text

Abstract:

The scattering of time harmonic SH waves by arbitrary positions of circular cylindrical cavity is studied in continuous, homogeneous, isotropic, elastic strip region. In this paper, the completely analytical expression of total wave field is explicitly presented and the dynamic stress distribution is symbolically visualized in the strip region. The total wave field is divided into four sub wave fields, incident wave field and scattering wave field by the upper bound, the lower bound and the cylindrical bound, on big arc supposition. Specific wave functions are employed for each wave field expansion in series, such as circular cylindrical functions, respectively. Corresponding infinite linear algebraic equations are constructed by means of solving coefficients of Fourier series expansion on each sub wave field. Coefficients of cylindrical function expansion of each sub wave field are determined by truncated equations, which are reduced number of coefficients on pre-given computational accuracy. Numerical results graphically describe the dynamic stress concentration factor around the circumference of the cavity and the normalized dynamic stress along the cross section directly above the cavity.

APA, Harvard, Vancouver, ISO, and other styles

19

Zhou, Renlong, Mengxiong Wu, Hui Deng, Qiong Liu, Suxia Xie, Lingxi Wu, Guozheng Nie, and Jie Zhan. "High Absorption and Second-Harmonic Generation in Split Ring Resonator Multilayer Nanostructure." Journal of Nanomaterials 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/150957.

Full text

Abstract:

Second-harmonic generation in split ring resonator multilayer nanostructure is studied with the finite-difference time-domain (FDTD) method. The fundamental frequency wave and the second-harmonic generation at the resonant absorption wavelength are highly localized in the dielectric layer, and the absorption peak is sensitive to dielectric constant of the dielectric layer. Under the excitation of the plasmon resonances mode, the strong local field induces an expected increase of the second-harmonic generation with conversion efficiencies 10−6-10−7. The distributions of fundamental frequency electric field and second-harmonic electric field inside the central dielectric layer region are also shown.

APA, Harvard, Vancouver, ISO, and other styles

20

Habibović, Dino, Wilhelm Becker, and Dejan B. Milošević. "Symmetries and Selection Rules of the Spectra of Photoelectrons and High-Order Harmonics Generated by Field-Driven Atoms and Molecules." Symmetry 13, no. 9 (August 25, 2021): 1566. http://dx.doi.org/10.3390/sym13091566.

Full text

Abstract:

Using the strong-field approximation we systematically investigate the selection rules for high-order harmonic generation and the symmetry properties of the angle-resolved photoelectron spectra for various atomic and molecular targets exposed to one-component and two-component laser fields. These include bicircular fields and orthogonally polarized two-color fields. The selection rules are derived directly from the dynamical symmetries of the driving field. Alternatively, we demonstrate that they can be obtained using the conservation of the projection of the total angular momentum on the quantization axis. We discuss how the harmonic spectra of atomic targets depend on the type of the ground state or, for molecular targets, on the pertinent molecular orbital. In addition, we briefly discuss some properties of the high-order harmonic spectra generated by a few-cycle laser field. The symmetry properties of the angle-resolved photoelectron momentum distribution are also determined by the dynamical symmetry of the driving field. We consider the first two terms in a Born series expansion of the T matrix, which describe the direct and the rescattered electrons. Dynamical symmetries involving time translation generate rotational symmetries obeyed by both terms. However, those that involve time reversal generate reflection symmetries that are only observed by the direct electrons. Finally, we explain how the symmetry properties, imposed by the dynamical symmetry of the driving field, are altered for molecular targets.

APA, Harvard, Vancouver, ISO, and other styles

21

Liu, De Hong, Xiang Jun Wang, Wu Bing Zhu, and Dou Ji. "Propagation Characteristic Analysis of Shaft-Rated Electromagnetic Field Produced by Ship of Multiple Propellers in Shallow Ocean." Applied Mechanics and Materials 475-476 (December 2013): 1428–32. http://dx.doi.org/10.4028/www.scientific.net/amm.475-476.1428.

Full text

Abstract:

In order to discuss the propagation characteristic of shaft-rated (SR) electromagnetic (EM) field produced by the ship of multiple propellers in shallow ocean, analytical expressions of EM was derived by several time-harmonic vertical dipoles model based on single time-harmonic vertical dipole method. Firstly, the paper built the physical model of single time-harmonic vertical dipole in triple-layer mediums with uniform speed movement. Then from two factors of phase and frequency, according to vector superposition principle, the EM expressions were solved by n time-harmonic vertical dipoles in fixed position so as to provide theoreticl law for the research of propagation characteristic. Some valuable conclusions were rearched through simulation, including finding the maxmum EM value when frequency was same and phase was zero, and frepuency variation was no-effect to the SR EM field when phase was same. Lastly, the exprement results were anatomotic with theoreticl analysis and demonstrated the effectiveness the expressions.

APA, Harvard, Vancouver, ISO, and other styles

22

Sun, Huiyuan, Thushara D. Abhayapala, and Prasanga N. Samarasinghe. "Time Domain Spherical Harmonic Processing with Open Spherical Microphones Recording." Applied Sciences 11, no. 3 (January 25, 2021): 1074. http://dx.doi.org/10.3390/app11031074.

Full text

Abstract:

Spherical harmonic analysis has been a widely used approach for spatial audio processing in recent years. Among all applications that benefit from spatial processing, spatial Active Noise Control (ANC) remains unique with its requirement for open spherical microphone arrays to record the residual sound field throughout the continuous region. Ideally, a low delay spherical harmonic recording algorithm for open spherical microphone arrays is desired for real-time spatial ANC systems. Currently, frequency domain algorithms for spherical harmonic decomposition of microphone array recordings are applied in a spatial ANC system. However, a Short Time Fourier Transform is required, which introduces undesirable system delay for ANC systems. In this paper, we develop a time domain spherical harmonic decomposition algorithm for the application of spatial audio recording mainly with benefit to ANC with an open spherical microphone array. Microphone signals are processed by a series of pre-designed finite impulse response (FIR) filters to obtain a set of time domain spherical harmonic coefficients. The time domain coefficients contain the continuous spatial information of the residual sound field. We corroborate the time domain algorithm with a numerical simulation of a fourth order system, and show the proposed method to have lower delay than existing approaches.

APA, Harvard, Vancouver, ISO, and other styles

23

Vergel, Daniel Gómez, and Eduardo J. S. Villaseñor. "The time-dependent quantum harmonic oscillator revisited: Applications to quantum field theory." Annals of Physics 324, no. 6 (June 2009): 1360–85. http://dx.doi.org/10.1016/j.aop.2009.03.003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Li, Yi, R. Liqiang Feng, and Yan Qiao. "Improvement of harmonic spectra from superposition of initial state driven by homogeneous and inhomogeneous combined field." Canadian Journal of Physics 98, no. 2 (February 2020): 198–209. http://dx.doi.org/10.1139/cjp-2019-0002.

Full text

Abstract:

A larger harmonic cutoff with a higher harmonic yield is a necessary requirement for producing intense ultrashort extreme ultraviolet (XUV) and X-ray sources. In this paper, we present a potential method to improve the harmonic cutoff and harmonic yield from the superposition of initial states in the He atom driven by the low-intensity homogeneous and inhomogeneous combined field. The results can be separated into two parts, that is, (i) the extension of harmonic cutoff via the optimization of three-color homogeneous and inhomogeneous field (covering the carrier envelope phase, delay time, intensity ratio, and inhomogeneous effect); and (ii) the enhancement of harmonic yield via the superposition of ground state and excited state as the initial state. Consequently, a water window harmonic plateau with an intensity enhancement of six orders of magnitude can be obtained. Moreover, the harmonic plateau is contributed by a single harmonic emission peak. Finally, through the Fourier transformation of some selected harmonics on the spectral continuum, a number of sub-50 as water window attosecond pulses with the intensity enhancement of six orders of magnitude can be obtained.

APA, Harvard, Vancouver, ISO, and other styles

25

Silaev, A. A., A. A. Romanov, and N. V. Vvedenskii. "High Harmonic Generation from Oriented Asymmetric Molecules in the Presence of Static Electric Field." Journal of Physics: Conference Series 2249, no. 1 (April 1, 2022): 012004. http://dx.doi.org/10.1088/1742-6596/2249/1/012004.

Full text

Abstract:

Abstract We investigate the high harmonic generation during the interaction of the femtosecond laser field with oriented asymmetric diatomic molecules in the presence of an external static electric field. Based on the numerical solution of the time-dependent Schrödinger equation for the model one-electron system, we calculate the high harmonic generation spectrum for a wide range of static-field strengths. The possibilities for visualizing low-frequency (terahertz and mid-infrared) radiation using time-delay measurements of even high harmonics intensities are discussed.

APA, Harvard, Vancouver, ISO, and other styles

26

Lan, Wendi, Xinyu Wang, Yue Qiao, Shushan Zhou, Jigen Chen, Jun Wang, Fuming Guo, and Yujun Yang. "High-Intensity Harmonic Generation with Energy Tunability Produced by Robust Two-Color Linearly Polarized Laser Fields." Symmetry 15, no. 3 (February 23, 2023): 580. http://dx.doi.org/10.3390/sym15030580.

Full text

Abstract:

By using the numerical solution of the time-dependent Schrödinger equation, we theoretically explored the high-order harmonic generation process under the interaction of high-intensity two-color ultrashort driving laser pulses with atoms. The symmetry of the electric field of the laser pulse will be broken. The producing electric field was controlled at the subcycle level by an IR laser and its second harmonic, which has the unique characteristic that two sequential half-cycles become distinct, rather than merely opposite in sign. Compared with the case of the atom in the fundamental laser pulse, the harmonic efficiency showed an increase of 1∼2 orders of magnitude at specific harmonic order with this combined pulse action. Through the theoretical analysis with the “three-step model”, it was demonstrated that the enhancement of the harmonic intensity is due to the fast ionization of electrons at the ionization moment and the short time from ionization to recombination of ionized electrons. In addition, effects of the peak field amplitude ratio, the full width at half maximum, the phase delay of the two-color pulses, the laser intensity and ionization probability on the harmonic efficiency enhancement were also investigated.

APA, Harvard, Vancouver, ISO, and other styles

27

Wang, De-hua. "Photodetachment of the H– ion in a forced harmonic potential." Canadian Journal of Physics 98, no. 9 (September 2020): 883–92. http://dx.doi.org/10.1139/cjp-2019-0482.

Full text

Abstract:

The photodetachment of a H– ion in a forced harmonic potential driven by a general time-dependent oscillating electric field has been investigated in the semi-classical closed orbit theory for the first time. It is found that the driven electric field frequency can affect the photodetachment cross-section of this system greatly. If the frequency of the driving electric field is equal to the harmonic frequency, a resonance phenomenon occurs in the classical motion of the detached electron. The interference effect between the returning electron wave travelling along the closed orbit with the initial outgoing wave gets stronger, causing the photodetachment cross-section to oscillate in a complicated manner. When the frequency of the driving electric field is unequal to the harmonic frequency, the driving electric field can weaken or strengthen the oscillatory structure in the photodetachment cross-section. In addition, the strength and initial phase in the driving electric field can also influence the photodetachment dynamics of the system. Our work provides a new method for controlling the photodetachment of negative ions in a harmonic potential and may guide future experimental research for cavity dynamics or in the ion trap.

APA, Harvard, Vancouver, ISO, and other styles

28

Coccia, Emanuele, and Eleonora Luppi. "Time-dependent ab initio approaches for high-harmonic generation spectroscopy." Journal of Physics: Condensed Matter 34, no. 7 (November 23, 2021): 073001. http://dx.doi.org/10.1088/1361-648x/ac3608.

Full text

Abstract:

Abstract High-harmonic generation (HHG) is a nonlinear physical process used for the production of ultrashort pulses in XUV region, which are then used for investigating ultrafast phenomena in time-resolved spectroscopies. Moreover, HHG signal itself encodes information on electronic structure and dynamics of the target, possibly coupled to the nuclear degrees of freedom. Investigating HHG signal leads to HHG spectroscopy, which is applied to atoms, molecules, solids and recently also to liquids. Analysing the number of generated harmonics, their intensity and shape gives a detailed insight of, e.g., ionisation and recombination channels occurring in the strong-field dynamics. A number of valuable theoretical models has been developed over the years to explain and interpret HHG features, with the three-step model being the most known one. Originally, these models neglect the complexity of the propagating electronic wavefunction, by only using an approximated formulation of ground and continuum states. Many effects unravelled by HHG spectroscopy are instead due to electron correlation effects, quantum interference, and Rydberg-state contributions, which are all properly captured by an ab initio electronic-structure approach. In this review we have collected recent advances in modelling HHG by means of ab initio time-dependent approaches relying on the propagation of the time-dependent Schrödinger equation (or derived equations) in presence of a very intense electromagnetic field. We limit ourselves to gas-phase atomic and molecular targets, and to solids. We focus on the various levels of theory employed for describing the electronic structure of the target, coupled with strong-field dynamics and ionisation approaches, and on the basis used to represent electronic states. Selected applications and perspectives for future developments are also given.

APA, Harvard, Vancouver, ISO, and other styles

29

Liu, H., L. Q. Feng, and R. M. Sani. "Effects of inhomogeneous laser field in time and space on the generation of broad spectral continuum and ultrashort attosecond pulse." Modern Physics Letters B 34, no. 13 (February 28, 2020): 2050131. http://dx.doi.org/10.1142/s0217984920501316.

Full text

Abstract:

The inhomogeneous effects of laser field in time and space on the generations of high-order harmonic spectra and attosecond pulses from He atom have been investigated with the assistance of the frequency-chirping technique and the metallic nanostructure. We find that in different combinations of chirps and spatial inhomogeneous effects, not only can the harmonic cutoff be extended, but the single harmonic emission peak (HEP) can also be selected to contribute to the spectral continuum. In detail, with the combinations of (i) symmetric chirp in frequency and positive inhomogeneous effect in space or (ii) asymmetric down chirp in frequency and negative inhomogeneous effect in space, two broad spectral continua with bandwidths of 496 eV and 480 eV can be obtained. Further, by properly adding IR or UV controlling pulse, the harmonic emission efficiency can be enhanced by several orders of magnitude. The enhancement of harmonic yield from adding UV pulse is higher than that from adding IR pulse. Moreover, the difference of harmonic enhancement between UV combined field and IR combined field is much more obvious at lower controlling laser intensity. Through analyzing the ionization probability, we find that the higher enhancement of harmonic yield from UV combined field is because of UV-resonance-enhancement-ionization between the ground state and the excited state of He atom. Finally, by properly superposing some harmonics, a number of attosecond pulses with pulse durations of 45 as can be obtained.

APA, Harvard, Vancouver, ISO, and other styles

30

Gevorkyan, Ashot S., and Aleksander V. Bogdanov. "Time-Dependent 4D Quantum Harmonic Oscillator and Reacting Hydrogen Atom." Symmetry 15, no. 1 (January 16, 2023): 252. http://dx.doi.org/10.3390/sym15010252.

Full text

Abstract:

With the help of low-dimensional reference equations (ordinary differential equations) and the corresponding coordinate transformations, the non-stationary 4D quantum oscillator in an external field is reduced to an autonomous form. The latter, in particular, reflects the existence of a new type of dynamical symmetry that reduces the equation of motion of a non-stationary oscillator to an autonomous form that does not change with time. By imposing an additional constraint on the wave function of the isotropic oscillator, we have obtained the total wave functions of the reacting hydrogen atom in two different cases: (a) when the non-stationary frequency has two asymptotic values and there is no external field; and (b) when, in addition to the non-stationary frequency, an external force acts on the hydrogen atom. The transition S-matrix elements of various elementary atomic–molecular processes are constructed. The probabilities of quantum transitions of the hydrogen atom to others, including new bound states, are studied in detail, taking into account the influence of external forces.

APA, Harvard, Vancouver, ISO, and other styles

31

Kindl, Vladimir, Radek Cermak, Zelmira Ferkova, and Bohumil Skala. "Review of Time and Space Harmonics in Multi-Phase Induction Machine." Energies 13, no. 2 (January 19, 2020): 496. http://dx.doi.org/10.3390/en13020496.

Full text

Abstract:

Modern multiphase electric machines take advantage of additional degrees of freedom for various purposes, including harmonic current injection to increase torque per ampere. This new approach introduces a non-sinusoidal air gap flux density distribution causing additional technical problems and so the conventional assumptions need to be revised. The paper presents a methodology for synthesis of air gap magnetic field generated by a symmetrically distributed multiphase windings including the rotor field reaction due to the machine’s load. The proposed method is suitable either for single-layer or double layer windings and can be adopted either for full-pitched or chorded winding including slots effects. The article analyses the air gap flux density harmonic content and formulates conclusions important to multiphase induction motors. It also discusses effects of time harmonic currents and illustrates the principle of changing number of pole-pairs typical for harmonic currents being injected to increase torque.

APA, Harvard, Vancouver, ISO, and other styles

32

Zhao, Xu. "The Second Harmonic Effect of Fractional-order Azimuthally Varying Vector Optical Field." Journal of Physics: Conference Series 2242, no. 1 (April 1, 2022): 012002. http://dx.doi.org/10.1088/1742-6596/2242/1/012002.

Full text

Abstract:

Abstract We report for the first time the second-harmonic generation (SHG) of a fractional-order azimuthal varying vector optical field (FO-AVVOF). SHG process is achieved by a Type-II phase-matching BBO crystal. This nonlinear frequency conversion process reveals the topology multiplication rule and obtains the second harmonic optical field of the ultraviolet wavelength, which may have potential applications in ultraviolet micromachining and all-optical switching.

APA, Harvard, Vancouver, ISO, and other styles

33

Xu, Xiao-Hu, Yan-Jun Wang, and Xiang-Yang Miao. "Theoretical study of high-order harmonic generation from the hydrogen molecular ion with a dichromatic spatially inhomogeneous field." Modern Physics Letters B 32, no. 14 (May 20, 2018): 1850141. http://dx.doi.org/10.1142/s0217984918501415.

Full text

Abstract:

We theoretically investigate the enhancement of high-order harmonic generation by numerically solving the non-Born–Oppenheimer time-dependent Schrödinger equation from the hydrogen molecular ion in a dichromatic inhomogeneous laser field. An ultrabroad supercontinuum up to 300 orders spectral width is generated. It is found that not only the inhomogeneity, but also the dichromatic field contributes to the significant extension of the harmonic cutoff compared with a monochromatic inhomogeneous laser field. Meanwhile, the long quantum paths can be suppressed and short ones can be enhanced by selecting optimized inhomogeneous parameter [Formula: see text], intensity and carrier envelope phase of the dichromatic inhomogeneous laser field. Furthermore, by superposing a properly selected range of the harmonic spectrum in the continuum region, an isolated 29-as pulse is generated. Both the classical theory and quantum time–frequency analysis are adopted to explain the physical mechanism.

APA, Harvard, Vancouver, ISO, and other styles

34

Nassar, Antnio B., and Ruth T. Berg. "Propagator for the time-dependent three-dimensional charged harmonic oscillator in a time-varying magnetic field." Physical Review A 34, no. 3 (September 1, 1986): 2462–65. http://dx.doi.org/10.1103/physreva.34.2462.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Feng, Liqiang, and Hang Liu. "High-intensity attosecond X-ray source generation by using low-intensity spatial inhomogeneous mid-infrared pulse combined with an ultraviolet pulse." International Journal of Modern Physics B 31, no. 01 (January 10, 2017): 1650239. http://dx.doi.org/10.1142/s0217979216502398.

Full text

Abstract:

We theoretically investigate the high-order harmonic spectra and the attosecond pulse generation from He[Formula: see text] ion driven by the spatial inhomogeneous combined field, consisting of a two-color low-intensity mid-infrared pulse ([Formula: see text] W/cm2) and an ultraviolet (UV) pulse ([Formula: see text] W/cm2). The numerical results show that due to the spatial inhomogeneous effect, the harmonic cutoffs are remarkably extended, and a 986 eV super-continuum can be obtained. Further with the proper introduction of an UV pulse (from 60 nm to 20 nm) to the two-color field, the harmonic yields are enhanced, especially for adding the 30 nm pulse case, a 1113 eV super-continuum (corresponding to a 34.1 dB enhanced field) with less harmonic modulation and six orders of magnitude enhancement can be obtained. Similar calculations have been performed for He atom and an 896 eV super-continuum with four orders of magnitude enhancement can be produced. Time–frequency harmonic distribution and time-dependent electron populations show that the single short quantum path contribution is responsible for the less harmonic modulation and the laser-induced electron excitation is responsible for the harmonic enhancement. Finally, by properly superposing the harmonics, a series of sub-50-as pulses including the whole X-ray region with 3–6 orders of magnitude enhancement can be obtained.

APA, Harvard, Vancouver, ISO, and other styles

36

Kress, Rainer. "On the boundary operator in electromagnetic scattering." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 103, no. 1-2 (1986): 91–98. http://dx.doi.org/10.1017/s0308210500014037.

Full text

Abstract:

SynopsisFor radiating solutions to the time-harmonic Maxwell equations, it is shown that the boundary operator mapping the tangential components of the electric field into the tangential components of the magnetic field is a bounded bijective operator from the space of Holder continuous tangential fields with Hölder continuous surface divergence onto itself.

APA, Harvard, Vancouver, ISO, and other styles

37

Chen, Yanzuo, Xuxu Shen, Wendi Lan, Suyu Li, Fuming Guo, and Yujun Yang. "The High-Order Harmonic Generation from Atom Driven by Co-Rotating Laser Pulses Composed of Fundamental Frequency and High Frequency." Symmetry 14, no. 3 (March 3, 2022): 519. http://dx.doi.org/10.3390/sym14030519.

Full text

Abstract:

By numerically solving the time-dependent Schrödinger equation (TDSE), the harmonic generation process of atoms irradiated by corotating laser pulses composed of a fundamental-frequency and high-frequency field is systematically studied. Compared with the harmonic generated from atoms irradiated by counter-rotating two-color circularly polarized laser pulses, the harmonic efficiency of atoms irradiated by co-rotating two-color circularly polarized (CRTCCP) laser pulses with the same laser parameters is higher. The harmonics are generated by the multiphoton radiation transition after the bound electrons undergo a multiphoton absorption transition to a higher energy level. In addition, the variation of the harmonic efficiency with the field strength of different frequency components in the driving laser pulse is also studied. The circularly polarized harmonics with higher intensity can be obtained by optimizing the field strength of the driving laser field.

APA, Harvard, Vancouver, ISO, and other styles

38

Qiu, Hongbo, Kaiqiang Hu, Ran Yi, and Wei Yanqi. "Effect of high frequency harmonic voltage on the performance of line start permanent magnet synchronous motor." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 2 (March 4, 2019): 777–92. http://dx.doi.org/10.1108/compel-06-2018-0267.

Full text

Abstract:

Purpose A large number of high-frequency harmonic voltages exist in the output voltage of the inverter, which will affect the performance of the motor. The purpose of this paper is to obtain the influence of high frequency harmonic voltage on the performance of the line start permanent magnet synchronous motor (LSPMSM) and reveal the mechanism of influence. The research results can provide help for the design of LSPMSM driven by inverter drives. Design/methodology/approach First, the actual output voltage data of the inverter is collected, and then the fundamental voltage and high frequency harmonic voltage data can be obtained by performing the fast Fourier transformation method on the voltage data. Second, the finite element model is established. During the finite element calculation, the obtained fundamental voltage and the main harmonic voltage components are used as the voltage source. To research the effect of high frequency harmonic voltage on the performance of motor, a reference group without high frequency harmonic voltage is set up, which is used to compare and analyze the effect of high-frequency harmonics on the performance of the motor. To verify the correctness of the model, a prototype based on the model parameters is manufactured, and then the back EMF experiment and load experiment are performed. The test data and calculation results are compared and analyzed. Findings The coupling relationship between high frequency time harmonic magnetic field and low frequency space harmonic magnetic field is obtained. The stator copper loss and rotor eddy-current loss are calculated and analyzed under normal supply voltage and abnormal supply voltage, and the influence mechanism is revealed Originality/value The coupling relationship between high frequency time harmonic magnetic field and low frequency space harmonic magnetic field is obtained. The sensitivity of the high frequency harmonic voltage to the stator copper loss and rotor eddy-current loss is obtained, and the mechanism of losses change is revealed.

APA, Harvard, Vancouver, ISO, and other styles

39

Chen, Duo, and Robert McGough. "Fast calculations of time‐harmonic near field pressure distributions produced by triangular sources." Journal of the Acoustical Society of America 117, no. 4 (April 2005): 2560. http://dx.doi.org/10.1121/1.4788520.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

DeGersem, H., and T. Weiland. "Field-Circuit Coupling for Time-Harmonic Models Discretized by the Finite Integration Technique." IEEE Transactions on Magnetics 40, no. 2 (March 2004): 1334–37. http://dx.doi.org/10.1109/tmag.2004.824536.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

While, Peter T., Larry K. Forbes, and Stuart Crozier. "A time-harmonic target-field method for designing unshielded RF coils in MRI." Measurement Science and Technology 16, no. 4 (March 5, 2005): 997–1006. http://dx.doi.org/10.1088/0957-0233/16/4/012.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

While, Peter T., Larry K. Forbes, and Stuart Crozier. "A time-harmonic target-field method for designing shielded RF coils in MRI." Measurement Science and Technology 16, no. 6 (May 17, 2005): 1381–93. http://dx.doi.org/10.1088/0957-0233/16/6/021.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Ethem Anar, İbrahim, and Adil Misir. "Far-field patterns for time-harmonic acoustic plane waves in an inhomogeneous medium." Applied Mathematics and Computation 111, no. 1 (May 2000): 103–19. http://dx.doi.org/10.1016/s0096-3003(98)10121-2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Yang, Zhipeng, Xinping Gui, Ju Ming, and Guanghui Hu. "Bayesian approach to inverse time-harmonic acoustic scattering with phaseless far-field data." Inverse Problems 36, no. 6 (June 1, 2020): 065012. http://dx.doi.org/10.1088/1361-6420/ab82ee.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Adly, A. A., and S. K. Abd-El-Hafiz. "An evolutionary computation approach for time-harmonic field problems involving nonlinear magnetic media." Journal of Applied Physics 109, no. 7 (April 2011): 07D321. http://dx.doi.org/10.1063/1.3549606.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Liang, Mai-Lin, and Yue Jiang. "Time-dependent harmonic oscillator in a magnetic field and an electric field on the non-commutative plane." Physics Letters A 375, no. 1 (November 2010): 1–5. http://dx.doi.org/10.1016/j.physleta.2010.10.035.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

LI, DE-JUN, and YI TANG. "INTERACTIONS BETWEEN THE TIME-VARYING ELECTROMAGNETIC FIELD AND THE QUANTUM SOLITARY WAVE IN A FERROMAGNETIC CHAIN." Modern Physics Letters B 26, no. 24 (August 21, 2012): 1250160. http://dx.doi.org/10.1142/s0217984912501606.

Full text

Abstract:

Starting with the Heisenberg Hamiltonian of the one-dimensional ferromagnetic chain in external fields, we have studied quantum characteristics of solitary waves and interactions between solitary waves and the time-varying electromagnetic field. It is shown that the energy and magnetic moments of the solitary wave are quantized. Utilizing these novel results, we have obtained the Bloch's equation of the two-level quantum solitary wave in a simple harmonic magnetic field.

APA, Harvard, Vancouver, ISO, and other styles

48

Chen, Cong, Zhensheng Tao, Carlos Hernández-García, Piotr Matyba, Adra Carr, Ronny Knut, Ofer Kfir, et al. "Tomographic reconstruction of circularly polarized high-harmonic fields: 3D attosecond metrology." Science Advances 2, no. 2 (February 2016): e1501333. http://dx.doi.org/10.1126/sciadv.1501333.

Full text

Abstract:

Bright, circularly polarized, extreme ultraviolet (EUV) and soft x-ray high-harmonic beams can now be produced using counter-rotating circularly polarized driving laser fields. Although the resulting circularly polarized harmonics consist of relatively simple pairs of peaks in the spectral domain, in the time domain, the field is predicted to emerge as a complex series of rotating linearly polarized bursts, varying rapidly in amplitude, frequency, and polarization. We extend attosecond metrology techniques to circularly polarized light by simultaneously irradiating a copper surface with circularly polarized high-harmonic and linearly polarized infrared laser fields. The resulting temporal modulation of the photoelectron spectra carries essential phase information about the EUV field. Utilizing the polarization selectivity of the solid surface and by rotating the circularly polarized EUV field in space, we fully retrieve the amplitude and phase of the circularly polarized harmonics, allowing us to reconstruct one of the most complex coherent light fields produced to date.

APA, Harvard, Vancouver, ISO, and other styles

49

Bukhari, Syed Sabir Hussain, Ghulam Jawad Sirewal, Faheem Akhtar Chachar, and Jong-Suk Ro. "Dual-Inverter-Controlled Brushless Operation of Wound Rotor Synchronous Machines Based on an Open-Winding Pattern." Energies 13, no. 9 (May 2, 2020): 2205. http://dx.doi.org/10.3390/en13092205.

Full text

Abstract:

In an open-winding machine, three-phase stator currents can be controlled such that the input armature currents may contain the third-harmonic current component in addition to the fundamental. Considering this attribute of open-winding patterns, a harmonic current field excitation technique for a wound rotor synchronous machine (WRSM) is proposed in this paper based on the control of time-harmonic magneto-motive force. Two inverters connected to both terminals of the stator winding are controlled so that the input armature current generates an additional third-harmonic current component. This third-harmonic component generates a vibrating magnetic field that induces a current in the specially designed rotor harmonic winding. The current is supplied as DC current to the rotor excitation winding to generate a rotor field by using a full-bridge diode rectifier in order to achieve brushless operation. The proposed dual-inverter-controlled brushless operation for a WRSM is executed in ANSYS Maxwell using 2-D finite element analysis to validate its operation and electromagnetic performance.

APA, Harvard, Vancouver, ISO, and other styles

50

Aubanel, Eric E., and André D. Bandrauk. "Molecules in strong laser fields: vibrational inversion and harmonic generation." Canadian Journal of Chemistry 72, no. 3 (March 1, 1994): 673–77. http://dx.doi.org/10.1139/v94-092.

Full text

Abstract:

We examine two consequences of the unique behaviour of molecules in strong fields. First, by time gating of laser-induced avoided crossings with femtosecond laser pulses, one can obtain efficient vibrational inversion into a narrow distribution of vibrational levels of a molecular ion. We demonstrate this by numerical solution of the time-dependent Schrödinger equation for [Formula: see text] Second, we show results of numerical calculation with vibrationally excited [Formula: see text] of harmonic generation up to the 11th order of an intense 1064- nm laser. We predict that competition of photodissociation can be minimized by trapping the molecule in high-field-induced potential wells, thus enhancing the high-order harmonic generation process. Furthermore, the harmonic spectrum can serve as a measure of the structure of these laser-induced potentials.

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!