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Raj G, Hüller S. Impact of Laser Beam Speckle Structure on Crossed Beam Energy Transfer via Beam Deflections and Ponderomotive Self-Focusing. PHYSICAL REVIEW LETTERS 2017; 118:055002. [PMID: 28211711 DOI: 10.1103/physrevlett.118.055002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Indexed: 05/16/2023]
Abstract
The role of laser speckle structure (hot spots) and its ponderomotive self-focusing (PSF), in crossed beam energy transfer (CBET), of smoothed laser beams is investigated in an inhomogeneous expanding plasma. Numerical simulations using the code harmony in two spatial dimensions, demonstrate how self-focusing of laser hot spots in crossed beams can significantly affect the transfer of energy from one beam to the other in addition to the stimulated Brillouin scattering (SBS) process. It is shown that for sufficiently intense laser beams, when the laser hot spots exceed the criterion for self-focusing in a plasma with flow, the angular spread of transmitted light beams increases considerably with the intensity, which arises in particular, in expanding plasma where significant beam deflection is observed. It is shown for the first time that besides SBS, the contribution of speckle structure, PSF, and deflections of the intense hot spots in multiple speckle beams to CBET, therefore matters.
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Affiliation(s)
- G Raj
- Centre de Physique Théorique (CPHT), Ecole Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
| | - S Hüller
- Centre de Physique Théorique (CPHT), Ecole Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
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2
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Neuville C, Baccou C, Debayle A, Masson-Laborde PE, Hüller S, Casanova M, Marion D, Loiseau P, Glize K, Labaune C, Depierreux S. Spatial and Transient Effects during the Amplification of a Picosecond Pulse Beam by a Nanosecond Pump. PHYSICAL REVIEW LETTERS 2016; 117:145001. [PMID: 27740791 DOI: 10.1103/physrevlett.117.145001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Indexed: 06/06/2023]
Abstract
Amplification of a picosecond pulse beam by a lower intensity nanosecond pulse beam was experimentally observed in a flowing plasma. Modifications of intensity distributions in beam focal spots due to nonhomogeneous energy transfer and its transient regime were investigated. The mean transferred power reached 57% of the incident power of the nanosecond pulse beam. An imaging diagnostic allowed the intensity profile of the picosecond pulse beam to be determined, bringing to evidence the spatial nonuniformity of energy transfer in the amplified beam. This diagnostic also enabled us to observe the temporal evolution of the speckle intensity distribution because of the transfer. These results are reproduced by numerical simulations of two complementary codes. The method and the observed effects are important for the understanding of experiments with multiple crossing laser beams in plasmas.
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Affiliation(s)
| | - C Baccou
- LULI, UMR 7605 CNRS-Ecole Polytechnique-CEA-Université Paris VI, 91128 Palaiseau cedex, France
| | - A Debayle
- CEA, DAM, DIF, F-91297 Arpajon, France
| | | | - S Hüller
- Centre de Physique Théorique, UMR 7644, CNRS-Ecole Polytechnique, 91128 Palaiseau cedex, France
| | | | - D Marion
- CEA, DAM, DIF, F-91297 Arpajon, France
| | - P Loiseau
- CEA, DAM, DIF, F-91297 Arpajon, France
| | - K Glize
- LULI, UMR 7605 CNRS-Ecole Polytechnique-CEA-Université Paris VI, 91128 Palaiseau cedex, France
| | - C Labaune
- LULI, UMR 7605 CNRS-Ecole Polytechnique-CEA-Université Paris VI, 91128 Palaiseau cedex, France
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3
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Michel P, Divol L, Dewald EL, Milovich JL, Hohenberger M, Jones OS, Hopkins LB, Berger RL, Kruer WL, Moody JD. Multibeam Stimulated Raman Scattering in Inertial Confinement Fusion Conditions. PHYSICAL REVIEW LETTERS 2015; 115:055003. [PMID: 26274426 DOI: 10.1103/physrevlett.115.055003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Indexed: 06/04/2023]
Abstract
Stimulated Raman scattering from multiple laser beams arranged in a cone sharing a common daughter wave is investigated for inertial confinement fusion (ICF) conditions in a inhomogeneous plasma. It is found that the shared electron plasma wave (EPW) process, where the lasers collectively drive the same EPW, can lead to an absolute instability when the electron density reaches a matching condition dependent on the cone angle of the laser beams. This mechanism could explain recent experimental observations of hot electrons at early times in ICF experiments, at densities well below quarter critical when two plasmon decay is not expected to occur.
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Affiliation(s)
- P Michel
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - L Divol
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - E L Dewald
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - J L Milovich
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - M Hohenberger
- Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299, USA
| | - O S Jones
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - L Berzak Hopkins
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - R L Berger
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - W L Kruer
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - J D Moody
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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4
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Michel P, Divol L, Williams EA, Weber S, Thomas CA, Callahan DA, Haan SW, Salmonson JD, Dixit S, Hinkel DE, Edwards MJ, Macgowan BJ, Lindl JD, Glenzer SH, Suter LJ. Tuning the implosion symmetry of ICF targets via controlled crossed-beam energy transfer. PHYSICAL REVIEW LETTERS 2009; 102:025004. [PMID: 19257284 DOI: 10.1103/physrevlett.102.025004] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Indexed: 05/16/2023]
Abstract
Radiative hydrodynamics simulations of ignition experiments show that energy transfer between crossing laser beams allows tuning of the implosion symmetry. A new full-scale, three-dimensional quantitative model has been developed for crossed-beam energy transfer, allowing calculations of the propagation and coupling of multiple laser beams and their associated plasma waves in ignition hohlraums. This model has been implemented in a radiative-hydrodynamics code, demonstrating control of the implosion symmetry by a wavelength separation between cones of laser beams.
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Affiliation(s)
- P Michel
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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5
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Zhang P, Saleh N, Chen S, Sheng ZM, Umstadter D. Laser-energy transfer and enhancement of plasma waves and electron beams by interfering high-intensity laser pulses. PHYSICAL REVIEW LETTERS 2003; 91:225001. [PMID: 14683245 DOI: 10.1103/physrevlett.91.225001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2003] [Indexed: 05/24/2023]
Abstract
The effects of interference due to crossed laser beams were studied experimentally in the high-intensity regime. Two ultrashort (400 fs), high-intensity (4 x 10(17) and 1.6 x 10(18) W/cm(2)) and 1 microm wavelength laser pulses were crossed in a plasma of density 4 x 10(19) cm(3). Energy was observed to be transferred from the higher-power to the lower-power pulse, increasing the amplitude of the plasma wave propagating in the direction of the latter. This results in increased electron self-trapping and plasma-wave acceleration gradient, which led to an increased number of hot electrons (by 300%) and hot-electron temperature (by 70%) and a decreased electron-beam divergence angle (by 45%), as compared with single-pulse illumination. Simulations reveal that increased stochastic heating of electrons may have also contributed to the electron-beam enhancement.
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Affiliation(s)
- P Zhang
- FOCUS Center, University of Michigan, Ann Arbor, MI 48109, USA
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6
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Kirkwood RK, Moody JD, Langdon AB, Cohen BI, Williams EA, Dorr MR, Hittinger JA, Berger R, Young PE, Suter LJ, Divol L, Glenzer SH, Landen OL, Seka W. Observation of saturation of energy transfer between copropagating beams in a flowing plasma. PHYSICAL REVIEW LETTERS 2002; 89:215003. [PMID: 12443421 DOI: 10.1103/physrevlett.89.215003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2002] [Indexed: 05/24/2023]
Abstract
Experiments demonstrate energy and power transfer between copropagating, same frequency, beams crossing at a small angle in a plasma with a Mach 1 flow. The process is interpreted as amplification of the low intensity probe beam by the stimulated scatter of the high intensity pump beam. The observed probe amplification increases slowly with pump intensity and decreases with probe intensity, indicative of saturation limiting the energy and power transfer due to ion-wave nonlinearities and localized pump depletion. The results are consistent with numerical modeling including ion-wave nonlinearities.
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Affiliation(s)
- R K Kirkwood
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
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Seka W, Baldis HA, Fuchs J, Regan SP, Meyerhofer DD, Stoeckl C, Yaakobi B, Craxton RS, Short RW. Multibeam stimulated brillouin scattering from hot, solid-target plasmas. PHYSICAL REVIEW LETTERS 2002; 89:175002. [PMID: 12398677 DOI: 10.1103/physrevlett.89.175002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2002] [Indexed: 05/24/2023]
Abstract
We report on multibeam, laser-plasma interaction experiments in plasmas relevant to future direct-drive-ignition experiments. Six interaction beams are incident on preformed plasmas containing critical density. Stimulated Brillouin scattering (SBS) shows strong evidence of electromagnetic wave seeding of side- and backscattering. The data are also consistent with shared ion waves driven by the six symmetrically arranged interaction beams. Early SBS quenching is observed and attributed to the hydrodynamics of the plasma.
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Affiliation(s)
- W Seka
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
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Gildenburg VB, Zharova NA, Bakunov MI. Bulk-to-surface-wave self-conversion in optically induced ionization processes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 63:066402. [PMID: 11415230 DOI: 10.1103/physreve.63.066402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2000] [Indexed: 05/23/2023]
Abstract
Nonlinear time evolution of a p-polarized wave mode with inhomogeneous transverse structure producing tunnel ionization of a gas is investigated by numerical simulation and theoretical analysis. A phenomenon of trapping of electromagnetic radiation via its adiabatic conversion into surface waves guided by the field-created plasma structure is found out numerically. This process is accompanied by significant frequency downshifting of the electromagnetic radiation. The underlying physical mechanism is explained using a simple theoretical model. The described phenomena may play significant role in the self-channeling and frequency tuning of intense (approximately 10(14)-10(18) W/cm(2)) laser pulses in dense gases.
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Affiliation(s)
- V B Gildenburg
- Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603600, Russia
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