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Title: Rapid filamentation of high power lasers at the quarter critical surface

Abstract

A novel mechanism for initiating laser filamentation for intensities above 5 Multiplication-Sign 10{sup 17} W/cm{sup 2} is presented, seeded by the transient interference of an incident laser and its Raman backscattered daughter wave. For lasers propagating up short scale-length density gradients, the Raman reflectivity is peaked near the relativistically corrected quarter critical surface (RCQCS) and thus filamentation is observed to start on this surface. The filamentation at the RCQCS occurs on timescales comparable to the laser period. A series of 2D particle-in-cell (PIC) simulations confirm this physical model. Growth rates are obtained from simulations for a variety of simulation parameters and a simplified model in which the RCQCS behaves as a partially reflecting mirror, with the reflected light at double the wavelength of the incident light, is shown to reproduce the number and approximate location of filaments from PIC simulations. It was also proposed that field ionisation may alter RCQCS formation and the method of inclusion for this into the PIC simulation is presented. Additional simulations demonstrate field ionisation to have a negligible effect on the formation of the RCQCS. The implications of this filamentation mechanism for plasma experiments which require focused light of intensities above 5 Multiplication-Sign 10{sup 17}more » W/cm{sup 2} to propagate beyond the RCQCS are discussed.« less

Authors:
; ;  [1]
  1. Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom)
Publication Date:
OSTI Identifier:
22072491
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 19; Journal Issue: 6; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CALCULATION METHODS; FILAMENTS; INTERFERENCE; IONIZATION; LASERS; LIGHT TRANSMISSION; PLASMA; PLASMA SIMULATION; RAMAN SPECTRA; REFLECTIVITY; SURFACES; VISIBLE RADIATION; WAVELENGTHS

Citation Formats

Brady, C. S., Lawrence-Douglas, A., and Arber, T. D. Rapid filamentation of high power lasers at the quarter critical surface. United States: N. p., 2012. Web. doi:10.1063/1.4729333.
Brady, C. S., Lawrence-Douglas, A., & Arber, T. D. Rapid filamentation of high power lasers at the quarter critical surface. United States. doi:10.1063/1.4729333.
Brady, C. S., Lawrence-Douglas, A., and Arber, T. D. Fri . "Rapid filamentation of high power lasers at the quarter critical surface". United States. doi:10.1063/1.4729333.
@article{osti_22072491,
title = {Rapid filamentation of high power lasers at the quarter critical surface},
author = {Brady, C. S. and Lawrence-Douglas, A. and Arber, T. D.},
abstractNote = {A novel mechanism for initiating laser filamentation for intensities above 5 Multiplication-Sign 10{sup 17} W/cm{sup 2} is presented, seeded by the transient interference of an incident laser and its Raman backscattered daughter wave. For lasers propagating up short scale-length density gradients, the Raman reflectivity is peaked near the relativistically corrected quarter critical surface (RCQCS) and thus filamentation is observed to start on this surface. The filamentation at the RCQCS occurs on timescales comparable to the laser period. A series of 2D particle-in-cell (PIC) simulations confirm this physical model. Growth rates are obtained from simulations for a variety of simulation parameters and a simplified model in which the RCQCS behaves as a partially reflecting mirror, with the reflected light at double the wavelength of the incident light, is shown to reproduce the number and approximate location of filaments from PIC simulations. It was also proposed that field ionisation may alter RCQCS formation and the method of inclusion for this into the PIC simulation is presented. Additional simulations demonstrate field ionisation to have a negligible effect on the formation of the RCQCS. The implications of this filamentation mechanism for plasma experiments which require focused light of intensities above 5 Multiplication-Sign 10{sup 17} W/cm{sup 2} to propagate beyond the RCQCS are discussed.},
doi = {10.1063/1.4729333},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 6,
volume = 19,
place = {United States},
year = {2012},
month = {6}
}