Electromagnetic radiation from an inhomogeneous plasma: Theory and experiment

Means, R.W.

doi:10.1063/1.863326

Cited by 43 publications

(32 citation statements)

References 14 publications

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“…From equations (13) and (18), the coefficients R L and T T can be expressed in terms of the fields at X = 0 − , yielding (Means et al 1981)…”

Section: Derivation Of Mode Conversion Equationsmentioning

confidence: 99%

“…However, these analyses rely on an approximation which only allows an accurate estimation of the wave fields very close to the mode conversion point. For this reason, we follow the approach of Forslund et al (1975) and Means et al (1981), which yields exact solutions for the wave fields and does not involve any approximations beyond the assumptions that form the basis of the model. This paper is structured as follows: in Section 2, the derivation of the mode conversion equations is outlined.…”

Section: Introductionmentioning

confidence: 99%

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Mode Conversion and Reflection of Langmuir Waves in an Inhomogeneous Solar Wind

Willes

Cairns

2001

Publ. – Astron. Soc. Aust

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Beam-driven Langmuir waves in the solar wind are generated just above the electron plasma frequency, which fluctuates in the inhomogeneous solar wind plasma. Consequently, propagating Langmuir waves encounter regions in which the wave frequency is less than the local plasma frequency, where they can be reflected, mode converted to transverse electromagnetic waves, and trapped in density wells. The aim here is to investigate Langmuir wave reflection and mode conversion at a linear density gradient for typical solar wind parameters. It is shown that higher mode conversion efficiencies are possible than previously calculated, but that mode conversion occurs in a smaller region of parameter space. In addition, the possibility of detecting mode conversion with in situ spacecraft Langmuir wave observations is discussed.

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“…From equations (13) and (18), the coefficients R L and T T can be expressed in terms of the fields at X = 0 − , yielding (Means et al 1981)…”

Section: Derivation Of Mode Conversion Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mode Conversion and Reflection of Langmuir Waves in an Inhomogeneous Solar Wind

Willes

Cairns

2001

Publ. – Astron. Soc. Aust

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“…To go further and evaluate the actual generation efficiency, an alternative is to use the linear mode conversion theory already developed to study direct and inverse resonant absorption [37,56,57], in the simpler case where plasma oscillations are excited at a single frequency ω in the density gradient. These models describe the coupling between plasma and electromagnetic waves in a gradient with a linear density profile, in the case of an unmagnetized collisionless plasma.…”

Section: Analysis Using the Transverse Current Distributionmentioning

confidence: 99%

High-order harmonic and attosecond pulse generation on plasma mirrors: basic mechanisms

Thaury¹,

Quéré²

2010

J. Phys. B: At. Mol. Opt. Phys.

207

199

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To cite this version:Cédric Thaury, F Quéré. High-order harmonic and attosecond pulse generation on plasma mirrors: basic mechanisms. Journal of Physics B: Atomic, Molecular and Optical Physics, IOP Publishing, 2010, 43 (21) When an intense femtosecond laser pulse hits an optically-polished surface, it generates a dense plasma that itself acts as a mirror, known as a plasma mirror. As this mirror reflects the highintensity laser field, its non-linear temporal response can lead to a periodic temporal distortion of the reflected wave, associated to a train of attosecond light pulses, and, in the frequency domain, to the generation of high-order harmonics of the laser. This paper presents detailed theoretical and numerical analysis of the two dominant harmonic generation mechanisms identified so far, Coherent Wake Emission and the Relativistic Oscillating Mirror. Parametric studies of the emission efficiency are presented in these two regimes, and the phase properties of the corresponding harmonics are discussed. This theoretical study is complemented by a synthesis of recent experimental results, which establishes that these two mechanisms indeed dominate harmonic generation on plasma mirrors.

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“…Early workers favored nonlinear mechanisms due to the very highly nonthermal levels of Langmuir waves involved and because calculations suggested that the efficiency of LMC was inadequate. However, subsequent calculations for 1-D linear density gradients yield (power) conversion efficiencies ǫ ≈ 50 − 70% in a narrow angular window dependent on the properties of incoming Langmuir/z waves and density structures [16][17][18][19][20][21][22][23]. It was found that in magnetized plasmas ǫ slightly decreases and the mode conversion window becomes narrower compared with unmagnetized calculations [16,19].…”

Section: Introductionmentioning

confidence: 99%

Mode Conversion of Langmuir to Electromagnetic Waves with Parallel Inhomogeneity in the Solar Wind and the Corona

Kim¹,

Cairns²,

Robinson³

2008

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Linear mode conversion of Langmuir waves to radiation near the plasma frequency at density gradients is potentially relevant to multiple solar radio emissions, ionospheric radar experiments, laboratory plasma devices, and pulsars. Here we study mode conversion in warm magnetized plasmas using a numerical electron fluid simulation code with the density gradient parallel to the ambient magnetic field B0 for a range of incident Langmuir wavevectors. Our results include: (1) Both oand x-mode waves are produced for Ω ∝ (ωL) 1/3 (ωc/ω) 1, contrary to previous ideas. Only o mode is produced for Ω 1.5. Here ωc is the (angular) electron cyclotron frequency, ω the angular wave frequency, and L the length scale of the (linear) density gradient. (2) In the unmagnetized limit, equal amounts of o-and x-mode radiation are produced. (3) The mode conversion window narrows as Ω increases. (4) As Ω increases the total electromagnetic field changes from linear to circular polarization, with the o-and x-mode signals remaining circularly polarized. (5) The conversion efficiency to the x mode decreases monotonically as Ω increases while the o-mode conversion efficiency oscillates due to an interference phenomenon between incoming and reflected Langmuir/z modes. (6) The total conversion efficiency for wave energy from the Langmuir/z mode to radiation is typically less than 10%, but the corresponding power efficiencies differ by the ratio of the group speeds for each mode and are of order 50 − 70%. (7) The interference effect and the disappearance of the x mode at Ω 1 can be accounted for semiquantitatively using a WKB-like analysis. (8) Constraints on density turbulence are developed for the x mode to be generated and be able to propagate from the source. (9) Standard parameters for the corona and the solar wind near 1 AU suggest that linear mode conversion should produce both o-and x-mode radiation for solar and interplanetary radio bursts. It is therefore possible that linear mode conversion under these conditions might explain the weak total circular polarizations of type II and III solar radio bursts.

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Electromagnetic radiation from an inhomogeneous plasma: Theory and experiment

Cited by 43 publications

References 14 publications

Mode Conversion and Reflection of Langmuir Waves in an Inhomogeneous Solar Wind

Mode Conversion and Reflection of Langmuir Waves in an Inhomogeneous Solar Wind

High-order harmonic and attosecond pulse generation on plasma mirrors: basic mechanisms

Mode Conversion of Langmuir to Electromagnetic Waves with Parallel Inhomogeneity in the Solar Wind and the Corona

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