skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Plasma Modulation of Harmonic Emission Spectra from Laser-Plasma Interactions

Abstract

We report results from particle-in-cell simulations of the interaction of intense laser light with overdense plasma designed to examine the effects of plasma waves generated by pulses of fast electrons on high-order harmonic emission from the plasma. We show that the emission spectrum is modulated at the plasma frequency and identify combinations of parameters and circumstances favorable for modulation. In particular, the observed modulation is shown to depend not only on the chosen plasma electron density and intensity of the incident light but on the density profile and pulse shape.

Authors:
 [1];  [2]
  1. Centre for Physics, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom)
  2. Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Mexico 11801, Distrito Federal (Mexico)
Publication Date:
OSTI Identifier:
20957727
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 98; Journal Issue: 10; Other Information: DOI: 10.1103/PhysRevLett.98.105001; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ELECTRON DENSITY; ELECTRONS; EMISSION; EMISSION SPECTRA; LANGMUIR FREQUENCY; LASERS; MODULATION; PLASMA; PLASMA WAVES; PULSE SHAPERS; PULSES; SIMULATION; VISIBLE RADIATION

Citation Formats

Boyd, T. J. M., and Ondarza-Rovira, R. Plasma Modulation of Harmonic Emission Spectra from Laser-Plasma Interactions. United States: N. p., 2007. Web. doi:10.1103/PHYSREVLETT.98.105001.
Boyd, T. J. M., & Ondarza-Rovira, R. Plasma Modulation of Harmonic Emission Spectra from Laser-Plasma Interactions. United States. doi:10.1103/PHYSREVLETT.98.105001.
Boyd, T. J. M., and Ondarza-Rovira, R. Fri . "Plasma Modulation of Harmonic Emission Spectra from Laser-Plasma Interactions". United States. doi:10.1103/PHYSREVLETT.98.105001.
@article{osti_20957727,
title = {Plasma Modulation of Harmonic Emission Spectra from Laser-Plasma Interactions},
author = {Boyd, T. J. M. and Ondarza-Rovira, R.},
abstractNote = {We report results from particle-in-cell simulations of the interaction of intense laser light with overdense plasma designed to examine the effects of plasma waves generated by pulses of fast electrons on high-order harmonic emission from the plasma. We show that the emission spectrum is modulated at the plasma frequency and identify combinations of parameters and circumstances favorable for modulation. In particular, the observed modulation is shown to depend not only on the chosen plasma electron density and intensity of the incident light but on the density profile and pulse shape.},
doi = {10.1103/PHYSREVLETT.98.105001},
journal = {Physical Review Letters},
number = 10,
volume = 98,
place = {United States},
year = {Fri Mar 09 00:00:00 EST 2007},
month = {Fri Mar 09 00:00:00 EST 2007}
}
  • A Comment on the Letter by T. J. M. Boyd and R. Ondarza-Rovira [Phys. Rev. Lett. 98, 105001 (2007)]. The authors of the Letter offer a Reply.
  • We report results from recent investigations of the interaction of intense laser light with overdense plasma with particular emphasis on the harmonic emission spectrum generated in these interactions. The harmonic spectrum is governed by both the photon and electron densities, though dependence on the latter has been largely overlooked. To illustrate the effects of the plasma density we examine the characteristics of low-order harmonics by means of a simplified one-dimensional model and compare the spectra with particle-in-cell (PIC) simulations. Recent observations record a spectrum of harmonics showing distinct, if variable, modulation of between two and four harmonics. This spectral featuremore » proved highly sensitive to the incident intensity, with more pronounced modulation at higher intensities. In this paper we report on features of the emission spectrum across a wide parameter range and its dependence on the detailed structure of the plasma density profile. We find clear evidence of a modulated spectrum and identify the plasma frequency as the modulation frequency.« less
  • We have systematically investigated the second-harmonic (2..omega..) emission spectrum from 1.06-..mu..m laser-plasma interactions. Experimental data on the dependence of 2..omega.. spectrum, especially its broadness and complexity, on laser irradiation intensity, incidence angle, and prepulse are presented. A theoretical model using linear mode conversion and parametric decay instability processes can qualitatively explain the experimental results.
  • Experiments were performed in which intense laser pulses (up to 9x10{sup 19} W/cm{sup 2}) were used to irradiate very thin (submicron) mass-limited aluminum foil targets. Such interactions generated high-order harmonic radiation (greater than the 25th order) which was detected at the rear of the target and which was significantly broadened, modulated, and depolarized because of passage through the dense relativistic plasma. The spectral modifications are shown to be due to the laser absorption into hot electrons and the subsequent sharply increasing relativistic electron component within the dense plasma.
  • Particle-in-cell simulations have been used to explore the transition from the m{sup -8/3} decay in the power emitted by high harmonics to a regime for which the harmonic power P{sub m{approx}}m{sup -p}, where m denotes the harmonic number and p=5/3 or, less commonly, p=4/3. The deviation from the p=8/3 spectrum is interpreted as a consequence of the degree to which emission at the plasma frequency and its harmonics contribute to the spectrum. The research reported here explores conditions under which these deviations arise.