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Sherlock M, Michel P, Strozzi DJ, Divol L, Kur E, Zimmerman G. Inverse bremsstrahlung absorption rate for super-Gaussian electron distribution functions including plasma screening. Phys Rev E 2024; 109:055201. [PMID: 38907485 DOI: 10.1103/physreve.109.055201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 03/29/2024] [Indexed: 06/24/2024]
Abstract
We provide analytic expressions for the effective Coulomb logarithm for inverse bremsstrahlung absorption which predict significant corrections to the Langdon effect and overall absorption rate compared to previous estimates. The calculation of the collisional absorption rate of laser energy in a plasma by the inverse bremsstrahlung mechanism usually makes the approximation of a constant Coulomb logarithm. We dispense with this approximation and instead take into account the velocity dependence of the Coulomb logarithm, leading to a more accurate expression for the absorption rate valid in both classical and quantum conditions. In contrast to previous work, the laser intensity enters into the Coulomb logarithm. In most laser-plasma interactions the electron distribution function is super-Gaussian [Langdon, Phys. Rev. Lett. 44, 575 (1980)0031-900710.1103/PhysRevLett.44.575], and we find the absorption rate under these conditions is increased by as much as ≈30% compared to previous estimates at low density. In many cases of interest the correction to Langdon's predicted reduction in absorption is large; for example at Z=6 and T_{e}=400eV the Langdon prediction for the absorption is in error by a factor of ≈2. However, we also account for the additional effect of plasma screening, which predicts a reduction in absorption by a similar amount (up to ≈30%). These two effects compete to determine the overall absorption, which may be increased or decreased, depending on the conditions. The corrections can be incorporated into radiation-hydrodynamics simulation codes by replacing the familiar Coulomb logarithm with an analytic expression which depends on the super-Gaussian order "M" and the screening length.
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Affiliation(s)
- M Sherlock
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - P Michel
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D J Strozzi
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - L Divol
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - E Kur
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - G Zimmerman
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Hu K, Guo Z, Cao T, Liu S, Liu Z, Li Z, Xu Q, Chen K, Peng J. Study on the polarization dependence of nonlinear absorption of ultrafast laser pulses in bulk fused silica. OPTICS EXPRESS 2022; 30:8949-8958. [PMID: 35299335 DOI: 10.1364/oe.449608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/17/2022] [Indexed: 06/14/2023]
Abstract
By studying the nonlinear absorption of ultrafast laser pulses in fused silica, we examine, both with experiments and numerical simulations, the different polarization dependence of multiphoton ionization and avalanche ionization. Results show multiphoton ionization and avalanche ionization play different roles in femtosecond and picosecond laser micromachining, and the contribution via avalanche ionization increases with pulse duration. Meanwhile, the spatial distribution of the free carriers generated by circularly polarized pulses is more concentrated than those generated by linear polarization for picosecond laser pulses. These properties make the circular polarized ultrafast laser a possible way to improve the ultrafast laser micromachining efficiency and spatial quality, and can help to reduce some problematic nonlinear effects in ultrafast laser micromachining of low energy band materials.
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Gonsalves AJ, Nakamura K, Daniels J, Benedetti C, Pieronek C, de Raadt TCH, Steinke S, Bin JH, Bulanov SS, van Tilborg J, Geddes CGR, Schroeder CB, Tóth C, Esarey E, Swanson K, Fan-Chiang L, Bagdasarov G, Bobrova N, Gasilov V, Korn G, Sasorov P, Leemans WP. Petawatt Laser Guiding and Electron Beam Acceleration to 8 GeV in a Laser-Heated Capillary Discharge Waveguide. PHYSICAL REVIEW LETTERS 2019; 122:084801. [PMID: 30932604 DOI: 10.1103/physrevlett.122.084801] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/30/2019] [Indexed: 06/09/2023]
Abstract
Guiding of relativistically intense laser pulses with peak power of 0.85 PW over 15 diffraction lengths was demonstrated by increasing the focusing strength of a capillary discharge waveguide using laser inverse bremsstrahlung heating. This allowed for the production of electron beams with quasimonoenergetic peaks up to 7.8 GeV, double the energy that was previously demonstrated. Charge was 5 pC at 7.8 GeV and up to 62 pC in 6 GeV peaks, and typical beam divergence was 0.2 mrad.
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Affiliation(s)
- A J Gonsalves
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - K Nakamura
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J Daniels
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C Benedetti
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C Pieronek
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- University of California, Berkeley, California 94720, USA
| | - T C H de Raadt
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - S Steinke
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J H Bin
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - S S Bulanov
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J van Tilborg
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C G R Geddes
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C B Schroeder
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- University of California, Berkeley, California 94720, USA
| | - Cs Tóth
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - E Esarey
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - K Swanson
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- University of California, Berkeley, California 94720, USA
| | - L Fan-Chiang
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- University of California, Berkeley, California 94720, USA
| | - G Bagdasarov
- Keldysh Institute of Applied Mathematics RAS, Moscow 125047, Russia
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409, Russia
| | - N Bobrova
- Keldysh Institute of Applied Mathematics RAS, Moscow 125047, Russia
- Faculty of Nuclear Science and Physical Engineering, CTU in Prague, Brehova 7, Prague 1, Czech Republic
| | - V Gasilov
- Keldysh Institute of Applied Mathematics RAS, Moscow 125047, Russia
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409, Russia
| | - G Korn
- Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, 182 21 Prague, Czech Republic
| | - P Sasorov
- Keldysh Institute of Applied Mathematics RAS, Moscow 125047, Russia
- Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, 182 21 Prague, Czech Republic
| | - W P Leemans
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- University of California, Berkeley, California 94720, USA
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Weng SM, Sheng ZM, Zhang J. Inverse bremsstrahlung absorption with nonlinear effects of high laser intensity and non-Maxwellian distribution. Phys Rev E 2010; 80:056406. [PMID: 20365082 DOI: 10.1103/physreve.80.056406] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Indexed: 11/07/2022]
Abstract
Inverse bremsstrahlung (IB) absorption and evolution of the electron distribution function (EDF) in a wide laser intensity range (10;{12}-10;{17} W/cm;{2}) have been studied systematically by a two velocity-dimension Fokker-Planck code. It is found that Langdon's IB operator overestimates the absorption rate at high laser intensity, consequently with an overdistorted non-Maxwellian EDF. According to the small anisotropy of EDF in the oscillation frame, we introduce an IB operator which is similar to Langdon's but without the low laser intensity limit. This operator is appropriate for self-consistently tackling the nonlinear effects of high laser intensity as well as non-Maxwellian EDF. Particularly, our operator is capable of treating IB absorption properly in the indirect and direct-drive inertial confinement fusion schemes with the National Ignition Facility and Laser MegaJoule laser parameters at focused laser intensity beyond 10;{15} W/cm;{2} .
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Affiliation(s)
- Su-Ming Weng
- Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Beijing 100190, China
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David N, Hooker SM. Effects of polarization on inverse Bremsstrahlung heating of a plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:036402. [PMID: 16241574 DOI: 10.1103/physreve.72.036402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Indexed: 05/05/2023]
Abstract
A molecular dynamic (MD) code is used to compare the rates of heating by inverse Bremsstrahlung (IB) for circularly and linearly polarized radiation. For low intensities the heating rate is found to be independent of polarization. However, at higher intensities the variation of the heating rate with the radiation intensity is found to exhibit a sharper peak for circularly polarized than linearly polarized radiation. This difference is explained in terms of differences in the variation of the electron quiver speed during the optical cycle for linearly and circularly polarized radiation. An analytical expression--which includes a term which is nonlinear in the density of the plasma--for the rate of IB heating is fitted to the rates calculated by the MD code.
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Affiliation(s)
- N David
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
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