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Pulse duration

About: Pulse duration is a research topic. Over the lifetime, 19429 publications have been published within this topic receiving 286507 citations.


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Journal ArticleDOI
TL;DR: In this paper, a two-dimensional axisymmetric transient model that couples heat transfer and fluid flow is described that was constructed using the finite element method to predict the surface profile evolution on a free deformable surface.
Abstract: Extensive experimental work has shown that pulsed laser micro polishing (PLμP) is effective for polishing micro metallic parts. However, the process physics have not been fully understood yet, especially with respect to the melt pool flow. A reliable physical model can be of significant assistance in understanding the fluid flow in the melt pool and its effect on PLμP. In this paper, a two-dimensional axisymmetric transient model that couples heat transfer and fluid flow is described that was constructed using the finite element method. The model not only provided the solutions to the temperature and velocity fields but also predicted the surface profile evolution on a free deformable surface. The simulated melt depth and resolidified surface profiles matched those obtained from optical images of PLμPed Ti6Al4V sample cross-sections. The model was also used to study the effect of laser pulse duration on the melt pool flow. The study suggests that longer pulses produce more significant fluid flows. The cut-off pulse duration between capillary and thermocapillary regimes, below which minimal Maragoni flow should be expected, was estimated to be 0.66 μs for Ti6Al4V, which also matched well with the experimental results. It is evident that the coupled model offers reliable predictions and thus can be extended for a more complex parametric study to provide further insights for PLμP.

72 citations

Journal ArticleDOI
TL;DR: The duration of laser-accelerated, quasimonoenergetic electron bunches is demonstrated to be shorter than the drive laser pulse, but similar to the plasma period.
Abstract: Laser-plasma wakefield-based electron accelerators are expected to deliver ultrashort electron bunches with unprecedented peak currents. However, their actual pulse duration has never been directly measured in a single-shot experiment. We present measurements of the ultrashort duration of such electron bunches by means of THz time-domain interferometry. With data obtained using a 0.5 J, 45 fs, 800 nm laser and a ZnTe-based electro-optical setup, we demonstrate the duration of laser-accelerated, quasimonoenergetic electron bunches [best fit of 32 fs (FWHM) with a 90% upper confidence level of 38 fs] to be shorter than the drive laser pulse, but similar to the plasma period.

72 citations

Journal ArticleDOI
TL;DR: In this article, the first demonstration of the generation of efficient sub-nanosecond self-stimulated Raman pulses by a diode-pumped passively Q-switched Nd:GdVO4/Cr4+:YAG laser was reported.
Abstract: I report the first demonstration of the generation of efficient sub-nanosecond self-stimulated Raman pulses by a diode-pumped passively Q-switched Nd:GdVO4/Cr4+:YAG laser. The conversion efficiency for the average power is 7% from pump diode input to self-Raman output and the slope efficiency is up to 14%. At an incident pump power of 2.0 W, the pulse duration, pulse energy, and peak power for the Stokes wavelength of 1175.6 nm were found to be 750 ps, 6.3 μJ, and 8.4 kW, respectively, with a pulse-repetition rate of 22 kHz.

72 citations

Journal ArticleDOI
TL;DR: It is demonstrated that a variational ansatz based on a Gaussian pulse shape remains useful even when the actual pulse shape is not Gaussian, and it is shown that the enhancement factor saturates as the pulse duration decreases.
Abstract: We obtain and solve algebraic eigenvalue equations that predict the dependence of the pulse energy of a dispersion-managed soliton on pulse duration, chirp, and dispersion-map parameters. We demonstrate that a variational ansatz based on a Gaussian pulse shape remains useful even when the actual pulse shape is not Gaussian, and we show that the enhancement factor saturates as the pulse duration decreases.

72 citations

Proceedings Article
02 Jun 1996
TL;DR: In this article, the authors showed the maximal, minimal, and averaged possible values of the intensity of the harmonic as a function of the angular frequency detuning multiplied by the length of a harmonic pulse.
Abstract: Summary form only given. High harmonics are generated during the ionization of an atomic gas and therefore the probability of ionization, the number of unionized atoms, and the phase matching effects will impose a natural temporal envelope on the harmonic generation. We made some simulations which showed the maximal, minimal, and averaged possible values of the intensity of the harmonic as a function of the angular frequency detuning multiplied by the length of the harmonic pulse. From the envelope of the maximum signal we can extract the high harmonic pulse duration.

72 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023175
2022408
2021543
2020619
2019668
2018665