Power law decay of harmonic spectra in ultrarelativistic laser-plasma interactions

Boyd, Thomas J.; Ondarza-Rovira, R.

doi:10.1063/1.3480106

Cited by 4 publications

(3 citation statements)

References 14 publications

(10 reference statements)

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“…We note in passing that all three signatures of this spectrum, namely plasma emission at ω p and its harmonics, spectral decay with p = 5/3 and a cut-off in a range typically 100 m c 300 are consistent with the BOR spectra reported in references [6] and [9]. Furthermore, the localized electrostatic structures in their strongly turbulent state, the so-called soliton, is consistent with the trajectory crossings, as shown in figure 2.…”

Section: Plasma and Harmonic Emission From Relativistic Electrons Persupporting

confidence: 71%

“…These structures were identified as sources of emission at the plasma frequency and at its harmonics. Particle-in-cell simulations where used to explore the harmonic power decay in ultrarelativistic laser-plasma interactions by BOR [7][8][9] and spectral decays characterized by prevalent indexes p = 5/3 were found and, less commonly, p = 4/3 in p-polarized light incident on dense plasma targets. When the incident laser pulse is normal to the plasma surface, the spectrum is invariantly characterized by a power law described by the index 8/3, regardless of the combination of parameters (a 0 , n e /n c ), as shown in figure 1(a) [9].…”

Section: Plasma Effectsmentioning

confidence: 99%

“…Particle-in-cell simulations where used to explore the harmonic power decay in ultrarelativistic laser-plasma interactions by BOR [7][8][9] and spectral decays characterized by prevalent indexes p = 5/3 were found and, less commonly, p = 4/3 in p-polarized light incident on dense plasma targets. When the incident laser pulse is normal to the plasma surface, the spectrum is invariantly characterized by a power law described by the index 8/3, regardless of the combination of parameters (a 0 , n e /n c ), as shown in figure 1(a) [9]. Contrasting this, plasma effects are evident in the power harmonic decay for oblique incidence, since the excitation of plasma oscillations enable the enhancement of emission with lower harmonic power decay indexes, resulting in much flatter spectra, as shown in figure 1(b).…”

Section: Plasma Effectsmentioning

confidence: 99%

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Plasma effects in harmonic emission in relativistic laser interactions with overdense plasma targets examined from single particle radiation models

Ondarza-Rovira

Boyd

2012

J. Phys.: Conf. Ser.

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Multiple attosecond pulse generation in relativistically laser-driven overdense plasmas X Lavocat-Dubuis, F Vidal, J-P Matte et al.High-order harmonic generation using plasma mirrors F Quéré, C Thaury, H George et al. Abstract. Intense femtosecond laser pulses incident on supercritical plasmas can generate reflected high-order harmonics of the fundamental frequency that extend over the xuv spectral region, characterized by a power decay Pm ∼ m −p , where m is the harmonic number. It has been shown in earlier reports that plasma effects can modify the emission spectrum producing decay indexes p significantly weaker than the universal value 8/3 predicted by the similarity theory, these being within the range 4/3 ≤ p ≤ 8/3. In this paper we employ two single particle radiation models to demonstrate that plasma density effects substantially modify the emission radiated by a relativistic electron accelerated by the electric field of the laser pulse, and show that the harmonic power decay is commonly characterized by the indexes 4/3 and 5/3, with remarkable similitudes to those particle-in-cell results recently reported in ultrarelativistic laser-plasma interactions.

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Section: Plasma and Harmonic Emission From Relativistic Electrons Persupporting

confidence: 71%

Section: Plasma Effectsmentioning

confidence: 99%

Section: Plasma Effectsmentioning

confidence: 99%

See 1 more Smart Citation

Plasma effects in harmonic emission in relativistic laser interactions with overdense plasma targets examined from single particle radiation models

Ondarza-Rovira

Boyd

2012

J. Phys.: Conf. Ser.

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Saddle point approaches in strong field physics and generation of attosecond pulses

et al. 2019

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Radiation from Brunel-induced Langmuir waves in ultra-relativistic laser–plasma interactions

Ondarza-Rovira

Boyd

2015

Laser Part. Beams

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Intense laser light incident on solid targets has been shown to be a prolific source of harmonics. High harmonic intensities are characterized by a power-law spectrum Pm~m−p, where p denotes a spectral decay index and m is the harmonic number. Across a wide range of light intensity and target plasma density, particle-in-cell (PIC) simulations have shown p = 8/3, a value supported by the observation. However, the claim that this decay is universal has been contested and shown to break down in simulations when the incident light is P-polarized. Here weaker decays with p = 5/3 and at higher intensities p = 4/3 were observed. The distinction between the two regimes was attributed to the contribution to the spectrum from emission at the plasma frequency and its harmonics from Langmuir waves excited by the Brunel electrons generated when the incident light is P-polarized. In the present work, a single-particle model has been devised to lend support to a wide range of PIC data. The model incorporates a Langmuir electric field and is hybrid in the sense that we have made use of PIC output to guide our choice of field amplitudes in the Langmuir source. We find that the spectrum computed in this way shows generally satisfactory agreement with the corresponding PIC spectra, both in decay coefficient and spectral cut-off. At the highest intensities considered the emission from the convective bunching of electrons in high-amplitude Langmuir waves is itself superseded by Brunel electron bremsstrahlung and we have identified the regions of parameter space over which each of these sources is dominant. Interestingly, the same distinction has been drawn in a very different plasma regime where comparably complex spectra have been predicted in gamma-ray burst spectra from Langmuir turbulence produced in astrophysical jets.

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Power law decay of harmonic spectra in ultrarelativistic laser-plasma interactions

Cited by 4 publications

References 14 publications

Plasma effects in harmonic emission in relativistic laser interactions with overdense plasma targets examined from single particle radiation models

Plasma effects in harmonic emission in relativistic laser interactions with overdense plasma targets examined from single particle radiation models

Saddle point approaches in strong field physics and generation of attosecond pulses

Radiation from Brunel-induced Langmuir waves in ultra-relativistic laser–plasma interactions

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