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Title: Enhanced laser absorption from radiation pressure in intense laser plasma interactions

Abstract

The reflectivity of a short-pulse laser at intensities of 2 x 10 21Wcm -2 with ultra-high contrast (10 -15) on sub-micrometer silicon nitride foilswas studied experimentally using varying polarizations and target thicknesses. Furthermore, the reflected intensity and beam quality were found to be relatively constant with respect to intensity for bulk targets. For submicron targets, the measured reflectivity drops substantially without a corresponding increase in transmission, indicating increased conversion of fundamental to other wavelengths and particle heating. The experimental results and trends we observed in 3D particle-in-cell simulations emphasize the critical role of ion motion due to radiation pressure on the absorption process. Ion motion during ultra-short pulses enhances the electron heating, which subsequently transfers more energy to the ions.

Authors:
ORCiD logo [1];  [2];  [2];  [2];  [3];  [2];  [2];  [3];  [2]
  1. Univ. of California, Irvine, CA (United States). Dept. of Physics and Astronomy
  2. Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Sciences
  3. Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Sciences; Lancaster Univ. (United Kingdom). Dept. of Physics
Publication Date:
Research Org.:
Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1374977
Grant/Contract Number:
NA0002372; FA9550-12-1-0310; FA9550-14-1-0282; CHE-0840513
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
New Journal of Physics
Additional Journal Information:
Journal Volume: 19; Journal Issue: 6; Journal ID: ISSN 1367-2630
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Dollar, F., Zulick, C., Raymond, A., Chvykov, V., Willingale, L., Yanovsky, V., Maksimchuk, A., Thomas, A. G. R., and Krushelnick, K. Enhanced laser absorption from radiation pressure in intense laser plasma interactions. United States: N. p., 2017. Web. doi:10.1088/1367-2630/aa6fe2.
Dollar, F., Zulick, C., Raymond, A., Chvykov, V., Willingale, L., Yanovsky, V., Maksimchuk, A., Thomas, A. G. R., & Krushelnick, K. Enhanced laser absorption from radiation pressure in intense laser plasma interactions. United States. doi:10.1088/1367-2630/aa6fe2.
Dollar, F., Zulick, C., Raymond, A., Chvykov, V., Willingale, L., Yanovsky, V., Maksimchuk, A., Thomas, A. G. R., and Krushelnick, K. 2017. "Enhanced laser absorption from radiation pressure in intense laser plasma interactions". United States. doi:10.1088/1367-2630/aa6fe2. https://www.osti.gov/servlets/purl/1374977.
@article{osti_1374977,
title = {Enhanced laser absorption from radiation pressure in intense laser plasma interactions},
author = {Dollar, F. and Zulick, C. and Raymond, A. and Chvykov, V. and Willingale, L. and Yanovsky, V. and Maksimchuk, A. and Thomas, A. G. R. and Krushelnick, K.},
abstractNote = {The reflectivity of a short-pulse laser at intensities of 2 x 1021Wcm-2 with ultra-high contrast (10-15) on sub-micrometer silicon nitride foilswas studied experimentally using varying polarizations and target thicknesses. Furthermore, the reflected intensity and beam quality were found to be relatively constant with respect to intensity for bulk targets. For submicron targets, the measured reflectivity drops substantially without a corresponding increase in transmission, indicating increased conversion of fundamental to other wavelengths and particle heating. The experimental results and trends we observed in 3D particle-in-cell simulations emphasize the critical role of ion motion due to radiation pressure on the absorption process. Ion motion during ultra-short pulses enhances the electron heating, which subsequently transfers more energy to the ions.},
doi = {10.1088/1367-2630/aa6fe2},
journal = {New Journal of Physics},
number = 6,
volume = 19,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
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  • Interactions of 100-fs laser pulses with solid targets at intensities of 10{sup 18} W/cm{sup 2} and resultant terahertz (THz) radiation are studied under different laser contrast ratio conditions. THz emission is measured in the specular reflection direction, which appears to decrease as the laser contrast ratio varies from 10{sup -8} to 10{sup -6}. Correspondingly, the frequency spectra of the reflected light are observed changing from second harmonic dominant, three-halves harmonic dominant, to vanishing of both harmonics. Two-dimensional particle-in-cell simulation also suggests that this observation is correlated with the plasma density scale length change. The results demonstrate that the THz emissionmore » is closely related to the laser-plasma interaction processes. The emission is strong when resonance absorption is a key feature of the interaction, and becomes much weaker when parametric instabilities dominate.« less
  • An enhanced resonant acceleration scheme for electrons by intense circularly polarized laser pulse in a plasma with slowly attenuating density is proposed. As it propagates, the phase velocity and Doppler-shifted frequency of the laser both gradually decrease, so that the electrons moving in the combined laser and spontaneous fields can retain betatron resonance for a rather long time and effectively acquire energy from the laser. The theoretical analysis is verified by test-particle numerical calculations. It is shown that well-collimated GeV electron beams with very low beam divergence can be produced.
  • Two experiments studying the interaction of high intensity laser pulses (1x10{sup 19}-5x10{sup 20} W/cm{sup 2}) with underdense plasma are compared. The experiments used lasers that differed in power and focused intensity but had similar pulse duration ({approx}1 ps). Spectroscopic measurements of the forward scattered light (sidebands) near the fundamental laser frequency produced by the self-modulation instability were performed and the energies of electrons accelerated in the interaction are measured and compared. It is found that at high intensities the sideband intensities and the electron energies were not directly correlated, implying that relativistic plasma wave generation is not the most importantmore » mechanism for electron acceleration in the ultrahigh intensity regime. Simulation results for the forward scattered spectrum agree well with experimental results.« less
  • An overview of intense laser plasma interactions is given. The relevant physical processes range from collisional absorption to the excitation of instabilities, such as stimulated Raman and Brillouin scattering. These processes and important consequences that include suprathermal particle generation and enhanced absorption or scattering have been examined in theory, computer simulation, and experiments. The interaction physics has been studied in experiments using electromagnetic waves with wavelengths ranging from a fraction of a micron to tens of meters. Virtually every major interaction process has now been identified in laser plasma experiments, which have grown remarkably in sophistication over the years. Variousmore » control techniques have been demonstrated, and some intensity-wavelength regimes for efficient laser plasma coupling have been successfully identified. Indeed, current implosion experiments show excellent coupling of laser energy into thermal plasma. Future challenges include a better understanding of nonlinear levels, the competition of instabilities in large plasmas, and the beneficial effects of laser beam smoothing.« less
  • No abstract prepared.