Author: "Xu, M. H." / Topic: ultrashort laser pulses - Searchworks@Jio Institute Digital Library Search Results

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Start Over Author "Xu, M. H." Topic ultrashort laser pulses

Author: Sheng, Z. M., Li, Y. T., Chen, M., Ma, Y. Y., Yuan, X. H., Xu, M. H., Zheng, Z. Y., Liang, W. X., Yu, Q. Z., Zhang, Y., Liu, F., Wang, Z. H., Wei, Z. Y., Jin, Z., Zhang, J., Nakamura, T., and Mima, K.
Subjects: SOLID-state lasers, ACCELERATION (Mechanics), SURFACES of solids, ELECTRON emission, ELECTRON beams, CONES, THERMODYNAMICS, ULTRASHORT laser pulses, MAGNETIC fields
Abstract: Recent experimental and theoretical studies on surface electron emission will be presented. A collimated fast electron beam was observed along the target surface irradiated by intense laser pulses up to 20TW when the laser is incident with large angles such as over 45 degree. Numerical simulations suggest that such an electron beam is formed due to the confinement of the surface quasistatic electric and magnetic fields. Meanwhile, an acceleration process similar to the inverse-free-electron-laser is found to occur and is responsible for the generation of the most energetic electrons. A general formula for electron angular distributions accounting for the quasistatic electric and magnetic fields is given. In certain conditions, quasi-monoenergetic electron beams are also produced. These results are of interest for potential applications of laser-produced electron beams and helpful to the undersanding of the cone-target physics in the fast ignition related experiments. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]
Published: 2006
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Author: Su, L. N., Hu, Z. D., Zheng, Y., Liu, M., Li, Y. T., Wang, W. M., Sheng, Z. M., Yuan, X. H., Xu, M. H., Shen, Z. W., Fan, H. T., Chen, L. M., Lu, X., Ma, J. L., Wang, X., Wang, Z. H., Wei, Z. Y., and Zhang, J.
Subjects: ELECTRONIC modulation, PROTON beams, ULTRASHORT laser pulses, ALUMINUM foil, SPECTROMETERS
Abstract: Proton acceleration from 4 im thick aluminum foils irradiated by 30-TW Ti:sapphire laser pulses is investigated using an angle-resolved proton energy spectrometer. We find that a modulated spectral peak at ~0.82 MeV is presented at 2.5° off the target normal direction. The divergence angle of the modulated zone is 3.8°. Two-dimensional particle-in-cell simulations reveal that self-generated toroidal magnetic field at the rear surface of the target foil is responsible for the modulated spectral feature. The field deflects the low energy protons, resulting in the modulated energy spectrum with certain peaks. [ABSTRACT FROM AUTHOR]
Published: 2014
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Author: Xu, M. H., Li, Y. T., Carroll, D. C., Foster, P. S., Hawkes, S., Kar, S., Liu, F., Markey, K., McKenna, P., Streeter, M. J. V., Spindloe, C., Sheng, Z. M., Wahlström, C.-G., Zepf, M., Zheng, J., Zhang, J., and Neely, D.
Subjects: *FEMTOSECOND lasers research, *PROTON beams, *ULTRASHORT laser pulses, *PROTONS, *IONS
Abstract: A simple method to enhance ion generation with femtosecond ultraintense lasers is demonstrated experimentally by defocusing laser beams on target surface. When the laser is optimally defocused, we find that the population of medium and low energy protons from ultra-thin foils is increased significantly while the proton cutoff energy is almost unchanged. In this way, the total proton yield can be enhanced by more than 1 order, even though the peak laser intensity drops. The depression of the amplified spontaneous emission (ASE) effect and the population increase of moderate-energy electrons are believed to be the main reasons for the effective enhancement. [ABSTRACT FROM AUTHOR]
Published: 2012
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Author: Xu, M. H., Li, Y. T., Yuan, X. H., Yu, Q. Z., Wang, S. J., Zhao, W., Wen, X. L., Wang, G. C., Jiao, C. Y., He, Y. L., Zhang, S. G., Wang, X. X., Huang, W. Z., Gu, Y. Q., and Zhang, J.
Subjects: *PROTON beams, *SHOCK waves, *ULTRASHORT laser pulses, *HYDRODYNAMICS, *PLASMA lasers, *ELECTRIC fields, *ION bombardment, *METAL foils
Abstract: The characteristics of proton beam generated in the interaction of an ultrashort laser pulse with a large prepulse with solid foils are experimentally investigated. It is found that the proton beam emitted from the rear surface is not well collimated, and a “ring-like” structure with some “burst-like” angular modulation is presented in the spatial distribution. The divergence of the proton beam reduces significantly when the laser intensity is decreased. The “burst-like” modulation gradually fades out for the thicker target. It is believed that the large divergence angle and the modulated ring structure are caused by the shock wave induced by the large laser prepulse. A one-dimensional hydrodynamic code, MED103, is used to simulate the behavior of the shock wave produced by the prepulse. The simulation indicates that the rear surface of the foil target is significantly modified by the shock wave, consequently resulting in the experimental observations. [ABSTRACT FROM AUTHOR]
Published: 2006
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