Evidence of relativistic laser beam filamentation in back-reflected images

Tanaka, K. A.; Allen, M.; Pukhov, A.; Kodama, R.; Fujita, Hisanori; Kato, Yusuke; Kawasaki, T.; Kitagawa, Yoneyoshi; Mima, Kunioki; Morio, N.; Shiraga, H.; Iwata, Manabu; Miyakoshi, T.; Yamanaka, Tatsuhiko

doi:10.1103/physreve.62.2672

Cited by 28 publications

(15 citation statements)

References 19 publications

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“…The channeling or boring of an intense laser pulse in plasma and ion acceleration have been investigated extensively (Wilks et al, 1992;Borisov et al, 1992;Tabak et al, 1994;Zepf et al, 1996;Borghesi et al, 1997Borghesi et al, , 2002Borghesi et al, , 2007Fuchs et al, 1998;Vshivkov et al, 1998;Tanaka et al, 2000;Willi et al, 2001;Kodama et al, 2001;Najmudin et al, 2003;Hoffmann et al 2005;Flippo et al 2007;Laska et al 2007;Lei et al, 2007). In the relativistic-intensity regime, the relativistic ponderomotive force, which is proportional to the gradient of the laser intensity, dominates the laserplasma interaction (f p / ÀrI).…”

Section: Introductionmentioning

confidence: 99%

“…The laser pulse enters the plasma like a piston, pushing and compressing the plasma in front of it. However, the high-intensity laser-plasma interaction also leads to other nonlinear processes such as laser filamentation and breakup (Schifano et al, 1994;Tanaka et al, 2000;Osman et al, 2004), scattering and propagation instabilities (Najmudin et al, 2003;Bret & Deutsch, 2006;Laska et al, 2007;Gupta et al, 2007), etc., which can reduce the quality and length of the channel. Efficient channeling of a relativistic laser in higher density plasmas has been found to be rather difficult.…”

Section: Introductionmentioning

confidence: 99%

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Plasma channeling by multiple short-pulse lasers

Cao

et al. 2009

Laser Part. Beams

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Channeling by a train of laser pulses into homogeneous and inhomogeneous plasmas is studied using particle-in-cell simulation. When the pulse duration and the interval between the successive pulses are appropriate, the laser pulse train can channel into the plasma deeper than a single long-pulse laser of similar peak intensity and total energy. The increased penetration distance can be attributed to the repeated actions of the ponderomotive force, the continuous between-pulse channel lengthening by the inertially evacuating ions, and the suppression of laser-driven plasma instabilities by the intermittent laser-energy cut-offs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plasma channeling by multiple short-pulse lasers

Cao

et al. 2009

Laser Part. Beams

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“…At higher densities and especially when propagating over a large distance in the corona of a compressed target, small-scale self-focusing can easily break the beam into many filaments. Indications of this process were found in experiments by Tanaka et al 756 recording the back-reflected image of a 100-TW laser pulse incident on a long-scale-length plasma. Multiple highly intense spots were observed inside the original focal spot.…”

Section: A Channeling Conceptmentioning

confidence: 77%

Direct-drive inertial confinement fusion: A review

et al. 2015

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The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.

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“…[4][5][6][7][8][9][10][11][12][13][14][15] When the laser power exceeds the critical value P cr =17n c / n e GW, where n e and n c are the plasma and critical densities, respectively, it can undergo relativistic self-focusing ͑RSF͒. 4 The laser pulse can propagate in the overdense plasma because of relativistic induced transparency 5 ͑RIT͒ and laser hole boring ͑LHB͒.…”

Section: Introductionmentioning

confidence: 99%

Study of ultraintense laser propagation in overdense plasmas for fast ignition

et al. 2009

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Laser plasma interactions in a relativistic regime relevant to the fast ignition in inertial confinement fusion have been investigated. Ultraintense laser propagation in preformed plasmas and hot electron generation are studied. The experiments are performed using a 100 TW 0.6 ps laser and a 20 TW 0.6 ps laser synchronized by a long pulse laser. In the study, a self-focused ultraintense laser beam propagates along its axis into an overdense plasma with peak density 10 22 / cm 3 . Channel formation in the plasma is observed. The laser transmission in the overdense plasma depends on the position of its focus and can take place in plasmas with peak densities as high as 5 ϫ 10 22 / cm 3 . The hot electron beams produced by the laser-plasma interaction have a divergence angle of ϳ30°, which is smaller than that from laser-solid interactions. For deeper penetration of the laser light into the plasma, the use of multiple short pulse lasers is proposed. The latter scheme is investigated using particle-in-cell simulation. It is found that when the pulse duration and the interval between the pulses are appropriate, the laser pulse train can channel into the plasma deeper than a single longer pulse laser of similar peak intensity and total energy.

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Evidence of relativistic laser beam filamentation in back-reflected images

Cited by 28 publications

References 19 publications

Plasma channeling by multiple short-pulse lasers

Plasma channeling by multiple short-pulse lasers

Direct-drive inertial confinement fusion: A review

Study of ultraintense laser propagation in overdense plasmas for fast ignition

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