Journal articles: 'High power lasers. Laser-plasma interactions'

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Consoli, F., P. L. Andreoli, M. Cipriani, G. Cristofari, R. De Angelis, G. Di Giorgio, L. Duvillaret, et al. "Sources and space–time distribution of the electromagnetic pulses in experiments on inertial confinement fusion and laser–plasma acceleration." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, no. 2189 (December 7, 2020): 20200022. http://dx.doi.org/10.1098/rsta.2020.0022.

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When high-energy and high-power lasers interact with matter, a significant part of the incoming laser energy is transformed into transient electromagnetic pulses (EMPs) in the range of radiofrequencies and microwaves. These fields can reach high intensities and can potentially represent a significative danger for the electronic devices placed near the interaction point. Thus, the comprehension of the origin of these electromagnetic fields and of their distribution is of primary importance for the safe operation of high-power and high-energy laser facilities, but also for the possible use of these high fields in several promising applications. A recognized main source of EMPs is the target positive charging caused by the fast-electron emission due to laser–plasma interactions. The fast charging induces high neutralization currents from the conductive walls of the vacuum chamber through the target holder. However, other mechanisms related to the laser–target interaction are also capable of generating intense electromagnetic fields. Several possible sources of EMPs are discussed here and compared for high-energy and high-intensity laser–matter interactions, typical for inertial confinement fusion and laser–plasma acceleration. The possible effects on the electromagnetic field distribution within the experimental chamber, due to particle beams and plasma emitted from the target, are also described. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.

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Cairns, R. A., R. Bingham, P. Norreys, and R. Trines. "Laminar shocks in high power laser plasma interactions." Physics of Plasmas 21, no. 2 (February 2014): 022112. http://dx.doi.org/10.1063/1.4864328.

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Weng, Su-Ming, Zheng-Ming Sheng, Hui Xu, and Jie Zhang. "Vlasov-Fokker-Planck Simulations for High-Power Laser-Plasma Interactions." Communications in Computational Physics 11, no. 4 (April 2012): 1236–60. http://dx.doi.org/10.4208/cicp.060710.040811s.

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AbstractA review is presented on our recent Vlasov-Fokker-Planck (VFP) simulation code development and applications for high-power laser-plasma interactions. Numerical schemes are described for solving the kinetic VFP equation with both electron-electron and electron-ion collisions in one-spatial and two-velocity (1D2V) coordinates. They are based on the positive and flux conservation method and the finite volume method, and these two methods can insure the particle number conservation. Our simulation code can deal with problems in high-power laser/beam-plasma interactions, where highly non-Maxwellian electron distribution functions usually develop and the widely-used perturbation theories with the weak anisotropy assumption of the electron distribution function are no longer in point. We present some new results on three typical problems: firstly the plasma current generation in strong direct current electric fields beyond Spitzer-Härm’s transport theory, secondly the inverse bremsstrahlung absorption at high laser intensity beyond Langdon’s theory, and thirdly the heat transport with steep temperature and/or density gradients in laser-produced plasma. Finally, numerical parameters, performance, the particle number conservation, and the energy conservation in these simulations are provided.

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Krasik, Yakov, John Leopold, Guy Shafir, Yang Cao, Yuri Bliokh, Vladislav Rostov, Valery Godyak, et al. "Experiments Designed to Study the Non-Linear Transition of High-Power Microwaves through Plasmas and Gases." Plasma 2, no. 1 (March 8, 2019): 51–64. http://dx.doi.org/10.3390/plasma2010006.

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The interaction of powerful sub-picosecond timescale lasers with neutral gas and plasmas has stimulated enormous interest because of the potential to accelerate particles to extremely large energies by the intense wakefields formed and without being limited by high accelerating gradients as in conventional accelerator cells. The interaction of extremely high-power electromagnetic waves with plasmas is though, of general interest and also to plasma heating and wake-field formation. The study of this subject has become more accessible with the availability of sub-nanosecond timescale GigaWatt (GW) power scale microwave sources. The interaction of such high-power microwaves (HPM) with under-dense plasmas is a scale down of the picosecond laser—dense plasma interaction situation. We present a review of a unique experiment in which such interactions are being studied, some of our results so far including results of our numerical modeling. Such experiments have not been performed before, self-channeling of HPM through gas and plasma and extremely fast plasma electron heating to keV energies have already been observed, wakefields resulting from the transition of HPM through plasma are next and more is expected to be revealed.

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Li, Yu-Tong, Wei-Min Wang, Chun Li, and Zheng-Ming Sheng. "High power terahertz pulses generated in intense laser—plasma interactions." Chinese Physics B 21, no. 9 (September 2012): 095203. http://dx.doi.org/10.1088/1674-1056/21/9/095203.

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Willingale, L., P. M. Nilson, A. G. R. Thomas, S. S. Bulanov, A. Maksimchuk, W. Nazarov, T. C. Sangster, C. Stoeckl, and K. Krushelnick. "High-power, kilojoule laser interactions with near-critical density plasma." Physics of Plasmas 18, no. 5 (May 2011): 056706. http://dx.doi.org/10.1063/1.3563438.

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Campbell, E. M., T. C. Sangster, V. N. Goncharov, J. D. Zuegel, S. F. B. Morse, C. Sorce, G. W. Collins, et al. "Direct-drive laser fusion: status, plans and future." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 379, no. 2189 (December 7, 2020): 20200011. http://dx.doi.org/10.1098/rsta.2020.0011.

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Laser-direct drive (LDD), along with laser indirect (X-ray) drive (LID) and magnetic drive with pulsed power, is one of the three viable inertial confinement fusion approaches to achieving fusion ignition and gain in the laboratory. The LDD programme is primarily being executed at both the Omega Laser Facility at the Laboratory for Laser Energetics and at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. LDD research at Omega includes cryogenic implosions, fundamental physics including material properties, hydrodynamics and laser–plasma interaction physics. LDD research on the NIF is focused on energy coupling and laser–plasma interactions physics at ignition-scale plasmas. Limited implosions on the NIF in the ‘polar-drive’ configuration, where the irradiation geometry is configured for LID, are also a feature of LDD research. The ability to conduct research over a large range of energy, power and scale size using both Omega and the NIF is a major positive aspect of LDD research that reduces the risk in scaling from OMEGA to megajoule-class lasers. The paper will summarize the present status of LDD research and plans for the future with the goal of ultimately achieving a burning plasma in the laboratory. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.

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Nam, C. H., W. Tighe, S. Suckewer, U. Feldman, and J. Seely. "Generation of XUV Spectra by Powerful Picosecond Laser." International Astronomical Union Colloquium 102 (1988): 203–6. http://dx.doi.org/10.1017/s0252921100107705.

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AbstractThe development of laser action at wavelengths shorter than those of current X-ray lasers is being investigated along two fronts. In the first case, we are exploring the possibilities for laser action at 15.4 nm in Li-like AIXI and 12.9 nm in Li-like SiXII in a magnetically confined recombining plasma. Previous work on hydrogen-like carbon, CVI, led to lasing action at 18.2 nm. Recently, this has been applied to microscopy and first results from a soft X-ray laser microscope are presented. A new technique to generate shorter wavelength X-ray lasing involves the interaction of a high power laser with a preformed plasma. The Powerful Picosecond Laser (PP-Laser) System with an output power level of 20-30 GW and focussed power density of 1016- 1017W/cm2has recently become operational. The spectra of highly ionized atoms in the XUV region were recorded on a high resolution grazing incidence spectrometer for the PP-Laser beam interacting with different solid targets.

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WANG, NAIYAN, YUSHENG SHAN, WEIYI MA, DAWEI YANG, GONG KUN, XIAOJUN WANG, XIUZHANG TANG, YEZHENG TAO, JINGLONG MA, and XINGDONG JIANG. "Activities of developing high-power KrF lasers and studying laser plasmas interaction physics at CIAE." Laser and Particle Beams 20, no. 1 (January 2002): 119–22. http://dx.doi.org/10.1017/s0263034602201172.

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This report reviews the scientific activities on high power laser and laser plasma physics at CIAE. A 6-beam KrF excimer laser system (100 J/23 ns/248 nm/1013 W/cm2, 15 min/shot) has been built, the Raman technologies used to upgrade it to 1014 W/cm2 has been studied. A UV femtosecond Ti:sapphire/KrF hybrid laser (50 mJ/220 fs/248 nm/1017 W/cm2) has been developed also, hot electron generation research has been carried out in the fs laser. In the near future, the fs laser will be amplified in six-beam laser system to produce ultra-high intensity to do fundamental researches on Fast Ignition of ICF.

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HORA, HEINRICH. "Difference between relativistic petawatt-picosecond laser-plasma interaction and subrelativistic plasma-block generation." Laser and Particle Beams 23, no. 4 (October 2005): 441–51. http://dx.doi.org/10.1017/s0263034605050627.

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Some preliminary views are presented to the topic “Fast High Density Plasma Blocks Driven by Picosecond Terawatt Lasers” of the UWS-International Workshop 1–4 December 2004 in Sydney, Australia, underlining the motivation to explain the difference between the relativistic and the subrelativistic effects of ps-laser pulse interaction with plasma at powers above TW. This refers to specifically selected experimental and theoretical presentations at the workshop containing results for explaining the differences but also the important applications for studies on the fast ignitor scheme for application on nuclear fusion energy. One of the aims with relativistic proton beams is to realize conditions of spark ignition, while the subrelativistic case implies the generation of fast plasma blocks eventually with the possibility to ignite a fusion flame in uncompressed solid DT fuel for a power station with high efficiency.

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PEGORARO, F., S. ATZENI, M. BORGHESI, S. BULANOV, T. ESIRKEPOV, J. HONRUBIA, Y. KATO, et al. "Production of ion beams in high-power laser–plasma interactions and their applications." Laser and Particle Beams 22, no. 1 (March 2004): 19–24. http://dx.doi.org/10.1017/s0263034604221048.

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Energetic ion beams are produced during the interaction of ultrahigh-intensity, short laser pulses with plasmas. These laser-produced ion beams have important applications ranging from the fast ignition of thermonuclear targets to proton imaging, deep proton lithography, medical physics, and injectors for conventional accelerators. Although the basic physical mechanisms of ion beam generation in the plasma produced by the laser pulse interaction with the target are common to all these applications, each application requires a specific optimization of the ion beam properties, that is, an appropriate choice of the target design and of the laser pulse intensity, shape, and duration.

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Mangles, S. P. D., K. Krushelnick, Z. Najmudin, M. S. Wei, B. Walton, A. Gopal, A. E. Dangor, et al. "The generation of mono-energetic electron beams from ultrashort pulse laser–plasma interactions." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1840 (January 24, 2006): 663–77. http://dx.doi.org/10.1098/rsta.2005.1730.

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The physics of the interaction of high-intensity laser pulses with underdense plasma depends not only on the interaction intensity but also on the laser pulse length. We show experimentally that as intensities are increased beyond 10 20 W cm −2 the peak electron acceleration increases beyond that which can be produced from single stage plasma wave acceleration and it is likely that direct laser acceleration mechanisms begin to play an important role. If, alternatively, the pulse length is reduced such that it approaches the plasma period of a relativistic electron plasma wave, high-power interactions at much lower intensity enable the generation of quasi-mono-energetic beams of relativistic electrons.

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BATANI, DIMITRI, SABRINA BIAVA, SERGIO BITTANTI, and FABIO PREVIDI. "A cellular automaton model of laser–plasma interactions." Laser and Particle Beams 19, no. 4 (October 2001): 631–42. http://dx.doi.org/10.1017/s0263034601194103.

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This paper deals with the realization of a CA model of the physical interactions occurring when high-power laser pulses are focused on plasma targets. The low-level and microscopic physical laws of interactions among the plasma and the photons in the pulse are described. In particular, electron–electron interaction via the Coulomb force and photon–electron interaction due to ponderomotive forces are considered. Moreover, the dependence on time and space of the index of refraction is taken into account, as a consequence of electron motion in the plasma. Ions are considered as a fixed background. Simulations of these interactions are provided in different conditions and the macroscopic dynamics of the system, in agreement with the experimental behavior, are evidenced.

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Shi, Jilin, Diankai Wang, and Longcheng Huang. "Experimental Study on Interaction between Nanosecond Pulsed Laser and Normal Shock Wave." Shock and Vibration 2021 (August 20, 2021): 1–11. http://dx.doi.org/10.1155/2021/1326219.

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Nanosecond pulsed lasers possess two remarkable advantages: a high peak power density and the ability to break down air to form plasma readily. Therefore, they have significant practical value in the drag reduction of a supersonic body. An experimental investigation is conducted on the fundamental physical phenomenon of the interaction of the pulsed laser plasma with a normal shock wave to reveal the mechanism of drag reduction. Moreover, a high-precision schlieren system is developed to measure complex wave structures with a time resolution of up to 30 ns and a spatial resolution up to 1 mm. A high-speed particle image velocimetry system is set up to measure the velocity and vorticity of the flow field quantitatively; the system has a time resolution of up to 500 ns. The characteristics of the spherical shock wave and the high-temperature and low-density region induced by the laser plasma are presented. The flow characteristics and evolution process of the laser plasma under a normal shock wave are substantially revealed. The cause of the supersonic drag reduction by the pulsed laser plasma is illustrated with numerical simulation results. The following results are obtained in this study: the initial Mach number of the shock wave induced by the laser plasma increases with the laser energy, and the shape of the wave gradually evolves from a droplet shape to a spherical shape. The propagation velocity decreases with time and is close to the sound velocity after 50 μs. The shape of the initial high-temperature and low-density region is approximately spherical; it subsequently destabilizes to form a sharp spike structure in the laser’s incident direction. Ultimately, the region evolves into a double-vortex ring structure with upper and lower symmetry; the size of this region increases with the laser energy.

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Wheeler, Jonathan, Gérard Mourou, and Toshiki Tajima. "Laser Technology for Advanced Acceleration: Accelerating Beyond TeV." Reviews of Accelerator Science and Technology 09 (January 2016): 151–63. http://dx.doi.org/10.1142/s1793626816300073.

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The implementation of the suggestion of thin film compression (TFC) allows the newest class of high power, ultrafast laser pulses (typically 20[Formula: see text]fs at near-infrared wavelengths) to be compressed to the limit of a single-cycle laser pulse (2[Formula: see text]fs). Its simplicity and high efficiency, as well as its accessibility to a single-cycle laser pulse, introduce a new regime of laser–plasma interaction that enhances laser acceleration. Single-cycle laser acceleration of ions is a far more efficient and coherent process than the known laser-ion acceleration mechanisms. The TFC-derived single-cycle optical pulse is capable of inducing a single-cycle X-ray laser pulse (with a far shorter pulse length and thus an extremely high intensity) through relativistic compression. The application of such an X-ray pulse leads to the novel regime of laser wakefield acceleration of electrons in the X-ray regime, yielding a prospect of “TeV on a chip.” This possibility of single-cycle X-ray pulses heralds zeptosecond and EW lasers (and zeptoscience). The additional invention of the coherent amplification network (CAN) fiber laser pushes the frontier of high repetition, high efficiency lasers, which are the hallmark of needed applications such as laser-driven LWFA colliders and other, societal applications. CAN addresses the crucial aspect of intense lasers that have traditionally lacked the above properties.

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Dromey, B., C. Bellei, D. C. Carroll, R. J. Clarke, J. S. Green, S. Kar, S. Kneip, et al. "Third harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions." Laser and Particle Beams 27, no. 2 (March 12, 2009): 243–48. http://dx.doi.org/10.1017/s0263034609000329.

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AbstractAs the state of the art for high power laser systems increases from terawatt to petawatt level and beyond, a crucial parameter for routinely monitoring high intensity performance is laser spot size on a solid target during an intense interaction in the tight focus regime (<10 µm). Here we present a novel, simple technique for characterizing the spatial profile of such a laser focal spot by imaging the interaction region in third harmonic order (3ωlaser). Nearly linear intensity dependence of 3ωlaser generation for interactions >1019 Wcm−2 is demonstrated experimentally and shown to provide the basis for an effective focus diagnostic. Importantly, this technique is also shown to allow in-situ diagnosis of focal spot quality achieved after reflection from a double plasma mirror setup for very intense high contrast interactions (>1020 Wcm−2) an important application for the field of high laser contrast interaction science.

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Offenberger, A. A., and R. Fedosejevs. "KrF laser produced plasmas." Laser and Particle Beams 7, no. 3 (August 1989): 393–403. http://dx.doi.org/10.1017/s0263034600007357.

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KrF and other short wavelength lasers are ideal candidates for producing hot dense plasmas since the laser energy can be absorbed with high efficiency by classical mechanisms, thereby virtually eliminating anomalous absorption and the production of non-thermal electrons. A high power KrF laser system employing optical beam multiplexing and stimulated Brillouin scattering to produce pulses as short as 1 ns and focused intensities on target of 1011−1014 W/cm2 has been developed for producing such plasmas and studying laser/plasma interaction phenomena. A variety of studies on absorption, transport, ablation, X-ray conversion and stimulated scattering instabilities have been pursued with this ¼ μm laser on single atomic number and multi-layer targets. This paper briefly describes some of the features of the KrF laser system and highlights some of the characteristics of the hot dense plasmas produced.

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Ghoranneviss, M., and A. Salar Elahi. "Review on Recent Developments in Laser Driven Inertial Fusion." Science and Technology of Nuclear Installations 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/802054.

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Discovery of the laser in 1960 hopes were based on using its very high energy concentration within very short pulses of time and very small volumes for energy generation from nuclear fusion as “Inertial Fusion Energy” (IFE), parallel to the efforts to produce energy from “Magnetic Confinement Fusion” (MCF), by burning deuterium-tritium (DT) in high temperature plasmas to helium. Over the years the fusion gain was increased by a number of magnitudes and has reached nearly break-even after numerous difficulties in physics and technology had been solved. After briefly summarizing laser driven IFE, we report how the recently developed lasers with pulses of petawatt power and picosecond duration may open new alternatives for IFE with the goal to possibly ignite solid or low compressed DT fuel thereby creating a simplified reactor scheme. Ultrahigh acceleration of plasma blocks after irradiation of picosecond (PS) laser pulses of around terawatt (TW) power in the range of 1020 cm/s2was discovered by Sauerbrey (1996) as measured by Doppler effect where the laser intensity was up to about 1018 W/cm2. This is several orders of magnitude higher than acceleration by irradiation based on thermal interaction of lasers has produced.

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Yuan, DaWei, YuTong Li, LuNing Su, GuoQian Liao, ChuanLei Yin, BaoJun Zhu, and Jie Zhang. "Filaments in high-speed counter-streaming plasma interactions driven by high-power laser pulses." Science China Physics, Mechanics and Astronomy 56, no. 12 (November 16, 2013): 2381–85. http://dx.doi.org/10.1007/s11433-013-5343-7.

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Gu, Xiao Yan, Huan Li, and Lin Jie Li. "Effect of Laser Power on Stability of Laser-Twin-Wire Hybrid Welding Process." Applied Mechanics and Materials 341-342 (July 2013): 315–19. http://dx.doi.org/10.4028/www.scientific.net/amm.341-342.315.

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Based on the chaos theory and related algorithm, largest Lyapunov analysis of current of laser-twin-wire pulse MIG welding process are performed from the point of view of nonlinear time sequence. Largest Lyapunov exponent (LLE) of characteristic current under different laser power were calculated, meanwhile synchronous high-speed photography was adopted to observe arc shape and droplet transfer. The results indicate that arc shape and the force state of droplets changes as a result of interactions between laser plasma and arc plasma. Addition of low power laser intensifies the interplay of two arcs, which decreases the stability of welding process. When laser power reaches to a certain extent, a stable cathod spot and a conductive channel are obtained for arcs. Stable welding process and small welding spatter are acquired.

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KULIKOV, S. M., Y. V. DOLGOPOLOV, A. M. DUDOV, G. G. KOCHEMASOV, G. A. KIRILLOV, S. N. PEVNY, A. B. SMIRNOV, S. P. SMYSHLYAEV, S. A. SUKHAREV, and A. F. SHKAPA. "Laser with phase conjugation for high intensity interactions." Laser and Particle Beams 17, no. 4 (October 1999): 765–72. http://dx.doi.org/10.1017/s0263034699174226.

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We present the results of the experimental testing of the laser facility LAMBDA, created and built at the Institute of Experimental Physics of the Russian Federal Nuclear Center for generation of quasi-steady-state laser fields in microvolumes.The facility includes: a single mode generator of reference radiation (RR) producing about 10 mJ energy in a pulse of controlled length from 3 to 30 ns; a target chamber with an input objective focusing the RR beam to a micron-size spot, and a 280-mm-diameter parabolic mirror with the focal length also of 270 mm; a two-stage iodine amplifier with the small signal gain coefficient 3·105 per one pass, to the input of which radiation from the target chamber formed by the (microobjective + parabolic mirror) system is applied; a phase conjugating device with the system for the selection of the phase-conjugated component, which allows us to realize the pulse compression in the amplifier stages, and to provide the compensation of the optical aberrations after the second pass amplification and focusing of high-power radiation into the microvolume; a complex for diagnostics of plasma and laser radiation parameters.

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Garasz, Katarzyna, and Marek Kocik. "Experimental Investigations on Laser Ablation of Aluminum in Sub-Picosecond Regimes." Applied Sciences 10, no. 24 (December 12, 2020): 8883. http://dx.doi.org/10.3390/app10248883.

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Due to high power and ultrashort pulses, femtosecond lasers excel at (but are not limited to) processing materials whose thicknesses are less than 500 microns. Numerous experiments and theoretical analyses testify to the fact that there are solid grounds for the applications of ultrafast laser micromachining. However, with high costs and complexity of these devices, a sub-picosecond laser that might be an alternative when it comes to various micromachining applications, such as patterns and masks in thin metal foils, micro-nozzles, thermo-detectors, MEMS (micro electro-mechanical systems), sensors, etc. Furthermore, the investigation of sub-picosecond laser interactions with matter could provide more knowledge on the ablation mechanisms and experimental verification of existing models for ultrashort pulse regimes. In this article, we present the research on sub-picosecond laser interactions with thin aluminum foil under various laser pulse parameters. Research was conducted with two types of ultrafast lasers: a prototype sub-picosecond Yb:KYW laser (650 fs) and a commercially available femtosecond Ti:S laser (35 fs). The results show how the variables such as pulse width, energy, frequency, wavelength and irradiation time affect the micromachining process.

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De Moor, Roeland Jozef Gentil, Jeroen Verheyen, Peter Verheyen, Andrii Diachuk, Maarten August Meire, Peter Jozef De Coster, Mieke De Bruyne, and Filip Keulemans. "Laser Teeth Bleaching: Evaluation of Eventual Side Effects on Enamel and the Pulp and the Efficiency In Vitro and In Vivo." Scientific World Journal 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/835405.

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Light and heat increase the reactivity of hydrogen peroxide. There is no evidence that light activation (power bleaching with high-intensity light) results in a more effective bleaching with a longer lasting effect with high concentrated hydrogen peroxide bleaching gels. Laser light differs from conventional light as it requires a laser-target interaction. The interaction takes place in the first instance in the bleaching gel. The second interaction has to be induced in the tooth, more specifically in the dentine. There is evidence that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. The reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and effective photobleaching, that is, a direct interaction with the colour molecules in the dentine, however, is only possible with the argon (488 and 415 nm) and KTP laser (532 nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a risk with intrapulpal temperature elevation up to 22°C. Hypersensitivity is regularly encountered, being it of temporary occurrence except for a number of diode wavelengths and the Nd:YAG. The tooth surface remains intact after laser bleaching. At present, KTP laser is the most efficient dental bleaching wavelength.

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Hora, H., G. H. Miley, M. Ghoranneviss, and A. Salar Elahi. "Application of picosecond terawatt laser pulses for fast ignition of fusion." Laser and Particle Beams 31, no. 2 (May 3, 2013): 249–56. http://dx.doi.org/10.1017/s026303461300013x.

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AbstractIn this research, we presented the application of picosecond terawatt laser pulses for ultrahigh acceleration of plasma blocks for fast ignition of fusion. Ultrahigh acceleration of plasma blocks after irradiation of picosecond laser pulses of around terawatt power in the range of 1020 cm/s2was discovered by Sauerbrey (1996) as measured by Doppler effect where the laser intensity was up to about 1018W/cm2. This is several orders of magnitude higher than acceleration by irradiation based on thermal interaction of lasers has produced. This ultrahigh acceleration resulted from hydrodynamic computations at plane target interaction in 1978 at comparable conditions where the interaction was dominated by the nonlinear (generalized ponderomotive) forces where the laser energy was instantly converted into plasma motion in contrast to slow and delayed thermal collision processes. After clarifying this basic result, the application of the plasma blocks for side-on ignition of solid density or modestly compressed fusion fuel following the theory of Chu (1971) is updated in view of later discovered plasma properties and the ignition of deuterium tritium and of proton-11B appeared possible for a dozen of PW-PS laser pulses if an extremely high contrast ratio avoided relativistic self-focusing. A re-evaluation of more recent experiment confirms the acceleration by the nonlinear force, and the generation of the fusion flame with properties of Rankine-Hugoniot shocks is reported.

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Földes, István B., Barnabás Gilicze, Zsolt Kovács, and Sándor Szatmári. "Plasma Mirrors for Cleaning Laser Pulses from the Infrared to the Ultraviolet." EPJ Web of Conferences 167 (2018): 04001. http://dx.doi.org/10.1051/epjconf/201816704001.

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Ultrashort laser pulses are generally preceded by prepulses which - in case of high main pulse intensities - may generate preplasmas on solid surfaces, thus making the initial conditions for the interactions ambiguous. Infrared laser systems applied successfully, with high efficiency self-induced plasma mirrors for improving the contrast of the beam. Short wavelength laser beams however have a larger critical density in the plasma, and due to their deeper penetration the absorption is higher, the reflectivity, and the corresponding plasma mirror efficiency is lower. We show herewith that with carefully planned boundary conditions plasma mirrors can reach up to 70% efficiency even for KrF laser radiation. Our observations can be qualitatively explained by the classical Drude model. The high reflectivity allows the use of plasma mirrors even after the final amplification or before the last amplifier. Different arrangement proposals for its integration to our high power KrF laser system are given as well.

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Mahdieh, Mohammad Hossein, and Sahar Hosseinzadeh. "Numerical study of radiative opacity for carbon and aluminum plasmas produced by high power pulsed lasers." Laser and Particle Beams 31, no. 2 (May 9, 2013): 273–88. http://dx.doi.org/10.1017/s0263034613000244.

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AbstractIn this paper, the opacity of plasma in local thermodynamic equilibrium condition was investigated numerically. The plasma was assumed to be produced by interaction of high power pulse laser with carbon and aluminum. Spectrally resolved opacities under different plasma temperature and density conditions were calculated and radiative absorption due to three absorption mechanisms; inverse bremsstrahlung, photo-ionization, and line absorption in plasmas was studied numerically. The purpose of this study is to calculate the values of absorption for inverse bremsstrahlung and photo-ionization processes for aluminum and carbon plasmas and to compare them for those of cold matter. In this investigation, the influences of density and temperature on plasma absorption were evaluated. The calculation results show that the opacity strength strongly depends on the plasma temperature and density.

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ZVORYKIN, V. D., V. G. BAKAEV, I. G. LEBO, and G. V. SYCHUGOV. "Hydrodynamics of plasma and shock waves generated by the high-power GARPUN KrF laser." Laser and Particle Beams 22, no. 1 (March 2004): 51–57. http://dx.doi.org/10.1017/s0263034604221103.

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The electron-beam-pumped KrF laser installation GARPUN with a 100-J output energy and long 100-ns pulse duration has been used to investigate laser–target interactions in a broad range of laser intensities for small (150 μm) and large (∼1 cm) irradiated spots. For higher intensities (up to 5 × 1012 W/cm2), a conical shock wave was generated in condensed matter by megabar pressure at the ablation front. It propagated with a supersonic velocity in a quasisteady manner together with a conical shock wave inside a target. Evaporated target material moving with a velocity of ∼50 km/s formed an extended plasma corona of ∼5 mm length with an electron temperature of ∼100 eV. Emission spectra of plasma have been investigated in the extreme UV range 120–250 Å. For lower intensities (108–109 W/cm2), planar shock waves in normal density air were produced with initial velocities up to 4 km/s in the forward direction and 7 km/s in the opposite direction toward incident radiation. In rarefied air, the forward shock wave kept velocities constant whereas the backward ones were accelerated up to 30 km/s. Planar compression waves in transparent condensed matter were also demonstrated propagating with sonic velocity.

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MANGLES, S. P. D., B. R. WALTON, Z. NAJMUDIN, A. E. DANGOR, K. KRUSHELNICK, V. MALKA, M. MANCLOSSI, et al. "Table-top laser-plasma acceleration as an electron radiography source." Laser and Particle Beams 24, no. 1 (March 2006): 185–90. http://dx.doi.org/10.1017/s0263034606050373.

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A “table-top” high power laser has been used to generate beams of accelerated electrons up to energy of 20 MeV from interactions with underdense plasmas. The energy spectrum of these beams was measured using a magnetic spectrometer and proof-of-principle experiments were performed to evaluate the suitability of these beams for electron radiography applications.

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Willingale, L., A. G. R. Thomas, P. M. Nilson, H. Chen, J. Cobble, R. S. Craxton, A. Maksimchuk, et al. "Surface waves and electron acceleration from high-power, kilojoule-class laser interactions with underdense plasma." New Journal of Physics 15, no. 2 (February 18, 2013): 025023. http://dx.doi.org/10.1088/1367-2630/15/2/025023.

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Schille, Joerg, Sebastian Kraft, Theo Pflug, Christian Scholz, Maurice Clair, Alexander Horn, and Udo Loeschner. "Study on X-ray Emission Using Ultrashort Pulsed Lasers in Materials Processing." Materials 14, no. 16 (August 12, 2021): 4537. http://dx.doi.org/10.3390/ma14164537.

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The interaction of ultrashort pulsed laser radiation with intensities of 1013 W cm−2 and above with materials often results in an unexpected high X-ray photon flux. It has been shown so far, on the one hand, that X-ray photon emissions increase proportionally with higher laser power and the accumulated X-ray dose rates can cause serious health risks for the laser operators. On the other hand, there is clear evidence that little variations of the operational conditions can considerably affect the spectral X-ray photon flux and X-ray emissions dose. In order to enhance the knowledge in this field, four ultrashort pulse laser systems for providing different complementary beam characteristics were employed in this study on laser-induced X-ray emissions, including peak intensities between 8 × 1012 W∙cm−2 < I0 < 5.2 × 1016 W∙cm−2, up to 72.2 W average laser power as well as burst/bi-burst processing mode. By the example of AISI 304 stainless steel, it was verified that X-ray emission dose rates as high as H˙′ (0.07) > 45 mSv h−1 can be produced when low-intensity ultrashort pulses irradiate at a small 1 µm intra-line pulse distance during laser beam scanning and megahertz pulse repetition frequencies. For burst and bi-burst pulses, the second intra-burst pulse was found to significantly enhance the X-ray emission potentially induced by laser pulse and plasma interaction.

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Dondieu, Stephen D., Krystian L. Wlodarczyk, Paul Harrison, Adam Rosowski, Jack Gabzdyl, Robert L. Reuben, and Duncan P. Hand. "Process Optimization for 100 W Nanosecond Pulsed Fiber Laser Engraving of 316L Grade Stainless Steel." Journal of Manufacturing and Materials Processing 4, no. 4 (November 26, 2020): 110. http://dx.doi.org/10.3390/jmmp4040110.

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High average power (>50 W) nanosecond pulsed fiber lasers are now routinely available owing to the demand for high throughput laser applications. However, in some applications, scale-up in average power has a detrimental effect on process quality due to laser-induced thermal accumulation in the workpiece. To understand the laser–material interactions in this power regime, and how best to optimize process performance and quality, we investigated the influence of laser parameters such as pulse duration, energy dose (i.e., total energy deposited per unit area), and pulse repetition frequency (PRF) on engraving 316L stainless steel. Two different laser beam scanning strategies, namely, sequential method (SM) and interlacing method (IM), were examined. For each set of parameters, the material removal rate (MRR) and average surface roughness (Sa) were measured using an Alicona 3D surface profilometer. A phenomenological model has been used to help identify the best combination of laser parameters for engraving. Specifically, this study has found that (i) the model serves as a quick way to streamline parameters for area engraving (ii) increasing the pulse duration and energy dose at certain PRF results in a high MRR, albeit with an associated increase in Sa, and (iii) the IM offers 84% reduction in surface roughness at a higher MRR compared to SM. Ultimately, high quality at high throughput engraving is demonstrated using optimized process parameters.

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Banas, C. M. "Multikilowatt Lasers in Manufacturing." Journal of Engineering for Gas Turbines and Power 115, no. 1 (January 1, 1993): 172–76. http://dx.doi.org/10.1115/1.2906673.

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The fundamentals of laser beam interactions with materials are discussed briefly and unique laser processing capabilities are noted. Introduction of this processing capability to manufacturing is reviewed. Typical high-volume production application requirements are identified and representative performance and production experience are described. Specific multikilowatt laser welding, piercing, and hardfacing applications in aerospace production are described. The evolution of production processes is discussed against the background of required processing capability. Also discussed are the unique laser processing capabilities that resulted in selection of the laser for production. Production experience is reviewed and cost saving factors are noted.

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Bittner, Stefan, Stefano Guazzotti, Yongquan Zeng, Xiaonan Hu, Hasan Yılmaz, Kyungduk Kim, Sang Soon Oh, Qi Jie Wang, Ortwin Hess, and Hui Cao. "Suppressing spatiotemporal lasing instabilities with wave-chaotic microcavities." Science 361, no. 6408 (August 16, 2018): 1225–31. http://dx.doi.org/10.1126/science.aas9437.

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Spatiotemporal instabilities are widespread phenomena resulting from complexity and nonlinearity. In broad-area edge-emitting semiconductor lasers, the nonlinear interactions of multiple spatial modes with the active medium can result in filamentation and spatiotemporal chaos. These instabilities degrade the laser performance and are extremely challenging to control. We demonstrate a powerful approach to suppress spatiotemporal instabilities using wave-chaotic or disordered cavities. The interference of many propagating waves with random phases in such cavities disrupts the formation of self-organized structures such as filaments, resulting in stable lasing dynamics. Our method provides a general and robust scheme to prevent the formation and growth of nonlinear instabilities for a large variety of high-power lasers.

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Eliezer, Shalom, and Jose M. Martinez-Val. "A novel fusion reactor with chain reactions for proton–boron11." Laser and Particle Beams 38, no. 1 (January 20, 2020): 39–44. http://dx.doi.org/10.1017/s0263034619000818.

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AbstractUsing a combination of laser–plasma interactions and magnetic confinement configurations, a conceptual fusion reactor is proposed in this paper. Our reactor consists of the following: (1) A background plasma of boron11 and hydrogen ions, plus electrons, is generated and kept for a certain time, with densities of the order of a mg/cm3 and temperatures of tens of eV. Both the radiation level and the plasma thermal pressure are thus very low. (2) A plasma channel is induced in a solid target by irradiation with a high power laser that creates a very intense shock wave. This mechanism conveys the acceleration of protons in the laser direction. The mechanisms must be tuned for the protons to reach a kinetic energy of 300–1200 keV where the pB11 fusion cross section is significantly large (note that this value is not a temperature). (3) Those ultra-fast protons enter the background plasma and collide with boron11 to produce three alphas. Fusion born alphas collide with protons of the plasma and accelerate them causing a chain reaction. (4) A combination of an induction current and a magnetic bottle keeps the chain reaction process going on, for a pulse long enough to get a high energy gain. (5) Materials for the background plasma and the laser target must be replaced for starting a new chain reaction cycle.

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Ondarza-Rovira, R., and T. J. M. Boyd. "Radiation from Brunel-induced Langmuir waves in ultra-relativistic laser–plasma interactions." Laser and Particle Beams 33, no. 2 (March 18, 2015): 157–62. http://dx.doi.org/10.1017/s0263034615000154.

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AbstractIntense 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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Cleveland, Danielle, Peter Stchur, Xiandeng Hou, Karl X. Yang, Jack Zhou, and Robert G. Michel. "Resonant Laser Ablation of Metals Detected by Atomic Emission in a Microwave Plasma and by Inductively Coupled Plasma Mass Spectrometry." Applied Spectroscopy 59, no. 12 (December 2005): 1427–44. http://dx.doi.org/10.1366/000370205775142656.

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It has been shown that an increase in sensitivity and selectivity of detection of an analyte can be achieved by tuning the ablation laser wavelength to match that of a resonant gas-phase transition of that analyte. This has been termed resonant laser ablation (RLA). For a pulsed tunable nanosecond laser, the data presented here illustrate the resonant enhancement effect in pure copper and aluminum samples, chromium oxide thin films, and for trace molybdenum in stainless steel samples, and indicate two main characteristics of the RLA phenomenon. The first is that there is an increase in the number of atoms ablated from the surface. The second is that the bandwidth of the wavelength dependence of the ablation is on the order of 1 nm. The effect was found to be virtually identical whether the atoms were detected by use of a microwave-induced plasma with atomic emission detection, by an inductively coupled plasma with mass spectrometric detection, or by observation of the number of laser pulses required to penetrate through thin films. The data indicate that a distinct ablation laser wavelength dependence exists, probably initiated via resonant radiation trapping, and accompanied by collisional broadening. Desorption contributions through radiation trapping are substantiated by changes in crater morphology as a function of wavelength and by the relatively broad linewidth of the ablation laser wavelength scans, compared to gas-phase excitation spectra. Also, other experiments with thin films demonstrate the existence of a distinct laser–material interaction and suggest that a combination of desorption induced by electronic transition (DIET) with resonant radiation trapping could assist in the enhancement of desorption yields. These results were obtained by a detailed inspection of the effect of the wavelength of the ablation laser over a narrow range of energy densities that lie between the threshold of laser-induced desorption of species and the usual analytical ablation regime. Normal ablation employs high-power lasers in an attempt to create a vapor plume without selective vaporization, and with a stoichiometry that accurately represents the stoichiometry of species in the solid sample. RLA, as a method of selective vaporization, appears to provide an opportunity to exploit selective vaporization in new ways.

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Mahmoad, Mahmoad SH. "The emission spectra and hydrodynamic properties of Al plasma using Nd-YAG laser." Iraqi Journal of Physics (IJP) 16, no. 38 (October 30, 2018): 83–98. http://dx.doi.org/10.30723/ijp.v16i38.12.

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In this work, the emission spectra and atomic structure of the aluminum target had been studied theoretically using Cowan code. Cowan code was used to calculate the transitions of electrons between atomic configuration interactions using the mathematical method called (Hartree-Fock). The aluminum target can give a good emission spectrum in the XUV region at 10 nm with oscillator strength of 1.82.The hydrodynamic properties of laser produced plasma (LPP) were investigated for the purpose of creating a light source working in the EUV region. Such a light source is very important for lithography (semiconductor manufacturing). The improved MEDUSA (Med103) code can calculate the plasma hydrodynamic properties (velocity, electron density, pressure, electron temperature, ion density, ion temperature and average ionization Z*). Aluminum target was considered in these calculations (Z=13). This work was done by using three laser power densities (1011, 1012 and 1013 W/cm2) with a 10 ns pulse width and 10 ps pulse width for laser wavelength (1064 nm). These laser intensities with 10 ns pulse width give high ionization stage of the Aluminum from 2.4-11 for electron range from 16.5-3000 eV.

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Ivanov, V. V., A. V. Maximov, K. J. Swanson, N. L. Wong, G. S. Sarkisov, P. P. Wiewior, A. L. Astanovitskiy, and A. M. Covington. "Experimental platform for investigations of high-intensity laser plasma interactions in the magnetic field of a pulsed power generator." Review of Scientific Instruments 89, no. 3 (March 2018): 033504. http://dx.doi.org/10.1063/1.5016973.

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Sharma, R. P., A. Monika, P. Sharma, P. Chauhan, and A. Ji. "Interaction of high power laser beam with magnetized plasma and THz generation." Laser and Particle Beams 28, no. 4 (October 19, 2010): 531–37. http://dx.doi.org/10.1017/s0263034610000583.

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AbstractThis paper presents an investigation of the excitation of a Tera hertz (THz) radiation by nonlinear interaction of a circularly polarized high power laser beam and density ripple in collisionless magneto plasma. The ponderomotive force due to the nonlinear interaction between the laser and density ripple generates a nonlinear current at a difference frequency. If the appropriate phase matching conditions are satisfied and the frequency of the ripple is appropriate, then this difference frequency can be brought in the THz range. Filamentation (self focusing) of a circularly polarized beam propagating along the direction of ambient magnetic field in plasma is first investigated within paraxial ray approximation. The beam gets focused when the initial power of the laser beam is greater than its critical power. Resulting localized beam couples with the pre-existing density ripple to produce a nonlinear current driving the THz radiation. Analytical expressions for the beam width of the laser beam, electric vector of the THz wave have been obtained. By changing the strength of the magnetic field, one can enhance or suppress the THz emission. For typical laser beam and plasma parameters with the incident laser power flux = 1014 W/cm2, laser beam radius (r0) = 40 µm, laser frequency (ω0) = 1014 rad/s and plasma density (n0) = 3 × 1018 cm−3, normalized ripple density amplitude (μ) = 0.3, the produced THz emission can be at the level of Giga watt in power.

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GAUTHIER, J. C., F. AMIRANOFF, C. CHENAIS-POPOVICS, G. JAMELOT, M. KOENIG, C. LABAUNE, E. LEBOUCHER-DALIMIER, C. SAUTERET, and A. MIGUS. "LULI activities in the field of high-power laser–matter interaction." Laser and Particle Beams 17, no. 2 (April 1999): 195–208. http://dx.doi.org/10.1017/s0263034699172057.

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LULI will play an important role as a major laser ICF and IFE support facility in Europe after recent or future changes (ASTERIX-Garching, CEA-Limeil) in large laser system programs. We will review the research activities which have been carried out at LULI during the last 2 years both in the nanosecond regime and in the subpicosecond ultraintense regime. As part of the LULI upgrade project, a new 30-J, 300-fs, 100-TW ultraintense laser chain has been commissioned in 1997. This laser has allowed the first complete demonstration of wakefield electron acceleration and is presently used to study new concepts in laser fusion and laser–plasma interaction experiments in the relativistic regime.

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41

Rose, S. J. "High-power laser-produced plasmas and astrophysics." Laser and Particle Beams 9, no. 4 (December 1991): 869–79. http://dx.doi.org/10.1017/s0263034600006613.

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The temperatures and the densities of plasmas produced by high-power lasers vary widely but in certain cases are similar to those found in astrophysical plasmas. In recent years our understanding of intense laser–matter interaction and the evolution of the resultingplasma has increased to the point where experiments can be designed to produce plasmas that allow astrophysical models to be tested. In this paper I review experimental work on laser-produced plasmas that is relevant to astrophysics. In the fields of highlyionized ion line identification and radiative opacity, relevant measurements have already been performed. Other experiments that could be performed with current laser facilities, including studies of X-ray nebula plasmas and complex radiation line transport, are described. In addition, experiments to investigate plasmas under more extreme conditions, which may be achievable with more powerful lasers, are mentioned.

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LÁSKA, L., K. JUNGWIRTH, J. KRÁSA, E. KROUSKÝ, M. PFEIFER, K. ROHLENA, J. ULLSCHMIED, et al. "Self-focusing in processes of laser generation of highly-charged and high-energy heavy ions." Laser and Particle Beams 24, no. 1 (March 2006): 175–79. http://dx.doi.org/10.1017/s0263034606060253.

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Laser-beam interaction with expanding plasma was investigated using the PALS high-power iodine-laser system. The interaction conditions are significantly changing with the laser focus spot position. The decisive role of the laser-beam self-focusing, participating in the production of ions with the highest charge states, was proved.

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43

Offenberger, A. A., R. Fedosejevs, P. D. Gupta, R. Popil, and Y. Y. Tsui. "Experimental results for high intensity KrF laser/plasma interaction." Laser and Particle Beams 4, no. 3-4 (August 1986): 329–48. http://dx.doi.org/10.1017/s0263034600002044.

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A high power KrF laser system employing beam multiplexing and stimulated Raman or Brillouin scattering to produce pulses as short as 1 ns and focused intensities on target of 1011 to 1014 W/cm2 has been developed for laser/plasma interaction research. A variety of investigations have been pursued on single and multilayer targets with variable atomic numbers. Absorption, transport, X-ray conversion, ion expansion characteristics, mass ablation and ablation pressure scaling, and stimulated scattering instabilities are among features that have been studied as a function of laser intensity. A wide variety of laser and target diagnostics are employed including focal plane imaging cameras for energy distribution and UV and soft X-ray streak cameras for temporally resolving the incident laser pulse and X-ray emission. Experimental results will be presented and our current understanding of the KrF laser/plasma interaction will be discussed.

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HORA, HEINRICH. "Smoothing and stochastic pulsation at high power laser-plasma interaction." Laser and Particle Beams 24, no. 3 (September 2006): 455–63. http://dx.doi.org/10.1017/s0263034606060617.

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Stochastic pulsation of laser-plasma interaction in the range of a few to dozens of picoseconds, due to standing wave produced density ripples, needs more attention than in the past, in view of the recent developments. This is important if nanosecond laser pulses produce a pre-compression that is a thousand times the solid state density of DT for fast ignition as well as for treatment of ps laser interaction. The following is an updated summary of these properties where the laser beam smoothing is essential. The use of smoothing is not only an empirical game with experiments for improving the interaction, but it is necessary to be aware of the mechanisms involved for understanding how the pulsation is overcome, and conclusions can be derived systematically for further improvements and control of the phenomena.

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Yin, Jie, LiangLiang Yang, Xu Yang, Haihong Zhu, Dengzhi Wang, Linda Ke, Zemin Wang, Guoqing Wang, and Xiaoyan Zeng. "High-power laser-matter interaction during laser powder bed fusion." Additive Manufacturing 29 (October 2019): 100778. http://dx.doi.org/10.1016/j.addma.2019.100778.

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46

Seo, Youngjin, Dongkyoung Lee, and Sukhoon Pyo. "High-Power Fiber Laser Cutting for 50-mm-Thick Cement-Based Materials." Materials 13, no. 5 (March 2, 2020): 1113. http://dx.doi.org/10.3390/ma13051113.

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This experimental research highlights the applicability of laser cutting to cement-based materials using multimode fiber lasers. A 9 kW multimode fiber laser is used, and the experimental variables are the water-to-cement ratio, laser speed, and material compositions such as cement paste, cement mortar and ultra high performance concrete (UHPC). The laser cutting performance on the cement-based materials is investigated in the downward laser direction. The kerf width and penetration depth of the cement-based materials are quantitatively evaluated with the parameters in the surface and cross section of the specimens after the laser cutting. Moreover, the material removal zone of each specimen is compared in terms of the penetration shapes in the cross-sectional view. Based on experimental observations, the interaction mechanism between the laser and cement-based materials is proposed.

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Sharma, Prerana. "Excitation of electron plasma wave by filamented laser beam and third-harmonic generation in magneto plasma." Laser and Particle Beams 33, no. 3 (May 14, 2015): 415–24. http://dx.doi.org/10.1017/s0263034615000300.

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AbstractThe combined effects of filamentation and magnetic field on the third-harmonic generation of electromagnetic beams have been investigated considering extended paraxial rays in magneto plasma. The analysis is done using eikonal method in which eikonal and other relevant quantities are extended up to fourth power of r. The time scale of laser beam is chosen such that the relativistic mass variation of electron becomes dominated source of nonlinearity in refractive index. The expression for coupling between ultra-intense laser beam and electron plasma wave due to relativistic nonlinearity has been deduced. Interaction of the seed plasma wave with the incident filamented laser beam excites the plasma wave and generates third harmonics. The expressions for plasma wave power and third-harmonic power have been derived. The effect of the magnetic field on the power of plasma wave and the third-harmonic power has been carried out. The role of magnetic field has been found to decrease the power of plasma wave and so as the power of third harmonic. Our results can be helpful for various laser plasma diagnostics experiments in which magnetic field present externally or generated spontaneously in the high-power laser–plasma interaction.

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48

DESAI, TARA. "High power laser interaction with clusters." Laser and Particle Beams 19, no. 1 (January 2001): 163–68. http://dx.doi.org/10.1017/s0263034601191263.

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Response of clusters to laser radiation depends on the laser parameters like wavelength, pulse duration, field, and so forth. At moderate laser intensities, I ∼ 1012 W/cm2, using a laser beam of wavelength 1.06 μm and 10-ns pulse duration, we have studied X-ray emission spectra from aluminum clusters of diameter 0.4 μm and gold clusters of 1.25 μm. Aluminum clusters show a different spectra compared to bulk material whereas gold clusters evolve towards bulk gold. Results are analyzed on the basis of cluster dimension, laser wavelength, and pulse duration. At higher laser intensities ≥1018 W/cm2, clusters undergo Coulomb explosion, giving rise to energetic electrons and ions. Here we discuss the possibility of harnessing these energetic particles for heating a small volume of the precompressed DT fuel to ignition condition relevant to fast ignition. Preliminary results are discussed.

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Glotov, A. N., Yu V. Golubenko, V. A. Desyatskov, and A. V. Stepanov. "Certain Features of Interaction Between Laser Radiation and Metals." Herald of the Bauman Moscow State Technical University. Series Instrument Engineering, no. 1 (130) (February 2020): 15–32. http://dx.doi.org/10.18698/0236-3933-2020-1-15-32.

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The paper presents experimental investigation results concerning the problem of optimising the efficiency of interaction between laser radiation and metals. We used several types of Nd lasers featuring the desired combination of power, temporal and spatial radiation parameters as sources of the radiation required. To pump these lasers, we employed rectangular pulses at a periodicity eliminating effects characteristic of continuous-wave and pulsed laser operation modes. This limits the laser radiation parameters driving the interaction efficiency functions to strictly those parameters that match the single-pulse laser operation mode. Temporal radiation parameter variation involved measurements in the free-running and high-frequency Q-switching modes as well as adjusting pumping (lasing) pulse durations. Power parameter variation was implemented through altering radiation energy density over the irradiated surface. Spatial structure of the ablative radiation was varied by means of optical radiation transfer facilities and different laser emitters. The experimental investigation results allowed us to establish certain patterns concerning the interaction between laser radiation and metals as a function of radiation parameters listed

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Wu, Fenxiang, Zongxin Zhang, Xiaojun Yang, Jiabing Hu, Yi Xu, and Yuxin Leng. "Directly Measuring the Pulse Front Distortion of High-Peak-Power Femtosecond Lasers." Applied Sciences 10, no. 23 (November 30, 2020): 8586. http://dx.doi.org/10.3390/app10238586.

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Pulse front distortion occurring in lenses can broaden the temporal profile of the pulse at focus and therefore decrease the focused intensity, especially for large-aperture femtosecond lasers. A previously proposed self-reference cross correlator was improved to directly measure the pulse front distortion of high-peak-power femtosecond lasers. The measured results of a 200 TW/27 fs laser are in good accordance with the calculated value. Moreover, the temporal intensity distribution of the pulse in the focal region was also investigated, in order to better guide and further promote the strong laser-matter interaction investigations. According to the measured PFD, the effective pulse duration at far field of this 200 TW laser was theoretically simulated to be ≈49 fs, which is almost two times the generally regarded 27 fs. As a result, the actually available focused intensity of this laser is only 55% of the case without pulse front distortion.

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Journal articles on the topic 'High power lasers. Laser-plasma interactions'

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