Formation of a fine-dispersed liquid-metal target under the action of femto- and picosecond laser pulses for a laser-plasma radiation source in the extreme ultraviolet range

Vinokhodov, A Yu; Koshelev, K. N.; Krivtsun, V. M.; Krivokorytov, M. S.; Sidelnikov, Yu. V.; Medvedev, V. V.; Kompanets, V. O.; Melnikov, A. A.; Чекалин, С. В.

doi:10.1070/qe2016v046n01abeh015867

Cited by 24 publications

(18 citation statements)

References 3 publications

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“…That greatly simplifies the experiment while tin component provides the required plasma for the EUV light generation. To produce targets we use the previously developed droplet generator [15] ensuring the Plateau-Rayleight instability to split jets into droplets. The generator is synchronized with laser pulses what provides an accurate irradiation of a target.…”

Section: Methodsmentioning

confidence: 99%

“…where , P , T are the internal energy, the pressure and the temperature, respectively, for the electronic (subscript e) or ionic (subscript i) subsystems; α is the coefficient of electron-ion heat transfer, κ e is the coeffi-cient of electronic thermal conductivity which is determined using QMD simulations. Material motion in onedimensional hydrodynamics is described via the energy balance equations (14)- (15) which are supplemented by the equations of continuity momentum balance and the equation of state for the ionic post-system. The laser energy J L absorbed by a unit mass per unit time is represented in the form:…”

Section: Appendix B: 2t Hydrodynamicsmentioning

confidence: 99%

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Expansion and Fragmentation of a Liquid-Metal Droplet by a Short Laser Pulse

et al. 2018

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We report an experimental and numerical investigation of the fragmentation mechanisms of micrometer-sized metal droplet irradiated by ultrashort laser pulses. The results of the experiment show that the fast one-side heating of such a droplet may lead to either symmetric or asymmetric expansion followed by different fragmentation scenarios. To unveil the underlying processes leading to fragmentation we perform simulation of liquid-tin droplet expansion produced by the initial conditions similar to those in experiment using the smoothed particle hydrodynamics (SPH) method. Simulation demonstrates that a thin heated surface layer generates a ultrashort shock wave propagating from the frontal side to rear side of the droplet. Convergence of such shock wave followed by a rarefaction tale to the droplet center results in the cavitation of material inside the central region by the strong tensile stress. Reflection of the shock wave from the rear side of droplet produces another region of highly stretched material where the spallation may occur producing a thin spallation layer moving with a velocity higher than expansion of the central shell after cavitation. It is shown both experimentally and numerically that the threshold laser intensity necessary for the spallation is higher than the threshold required to induce cavitation in the central region of droplet. Thus, the regime of asymmetrical expansion is realized if the laser intensity exceeds the spallation threshold. The transverse and longitudinal expansion velocities obtained in SPH simulations of different regimes of expansion are agreed well with our experimental data. * grigorev@phystech.edu †

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Section: Methodsmentioning

confidence: 99%

Section: Appendix B: 2t Hydrodynamicsmentioning

confidence: 99%

Expansion and Fragmentation of a Liquid-Metal Droplet by a Short Laser Pulse

et al. 2018

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“…Intense, short-pulse laser radiation can produce strong shock waves in liquids leading in some spectacular cases to explosive cavitation and violent spallation of the material [1][2][3][4][5]. Such dramatic physical phenomena can readily find application, a very recent example of which is found in the field of nanolithography where microdroplets of liquid tin are used to create extreme ultraviolet (EUV) light [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…Recent developments [8,9], however, produced tentative but tantalizing evidence for significantly improved source performance when replacing the ns-prepulse with a ps-prepulse laser to produce a shock-wave-induced explosive fragmentation. Although some notable progress was made very recently [3][4][5]10], this process requires further investigation. This paper advances the understanding of the aforementioned systems by providing an experimental and theoretical study of the late-time dynamics of the deformation of free-falling tin microdroplets.…”

Section: Introductionmentioning

confidence: 99%

Expansion Dynamics after Laser-Induced Cavitation in Liquid Tin Microdroplets

et al. 2018

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The cavitation-driven expansion dynamics of liquid tin microdroplets is investigated, set in motion by the ablative impact of a 15-ps laser pulse. We combine high-resolution stroboscopic shadowgraphy with an intuitive fluid dynamic model that includes the onset of fragmentation, and find good agreement between model and experimental data for two different droplet sizes over a wide range of laser pulse energies. The dependence of the initial expansion velocity on these experimental parameters is heuristically captured in a single power law. Further, the obtained late-time mass distributions are shown to be governed by a single parameter. These studies are performed under conditions relevant for plasma light sources for extreme-ultraviolet nanolithography.

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“…Previously, we used the DG in Droplet on Demand (DoD) mode, when investigating the interaction of tin-containing droplets with a femtosecond laser pulse. 14 In the DoD mode, the gas pressure is sufficient only for the formation of a meniscus of a fuel on the nozzle orifice but is insufficient for the formation of a jet. In this case the DG can operate stably with a small frequency f ≤ 100 Hz.…”

Section: Introductionmentioning

confidence: 99%

Stable droplet generator for a high brightness laser produced plasma extreme ultraviolet source

Vinokhodov

Krivokorytov²,

Sidelnikov

et al. 2016

Review of Scientific Instruments

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We present the results of the low-melting liquid metal droplets generation based on excited Rayleigh jet breakup. We discuss on the operation of the industrial and in-house designed and manufactured dispensing devices for the droplets generation. Droplet diameter can be varied in the range of 30-90 μm. The working frequency of the droplets, velocity, and the operating temperature were in the ranges of 20-150 kHz, 4-15 m/s, and up to 250 °C, respectively. The standard deviations for the droplet center of mass position both their diameter σ < 1 μm at the distance of 45 mm from the nozzle. Stable operation in the long-term (over 1.5 h) was demonstrated for a wide range of the droplet parameters: diameters, frequencies, and velocities. Physical factors affecting the stability of the generator operation have been identified. The technique for droplet synchronization, allowing using the droplet as a target for laser produced plasma, has been created; in particular, the generator has been successfully used in a high brightness extreme ultraviolet (EUV) light source. The operation with frequency up to 8 kHz was demonstrated as a result of the experimental simulation, which can provide an average brightness of the EUV source up to ∼1.2 kW/mm sr.

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Formation of a fine-dispersed liquid-metal target under the action of femto- and picosecond laser pulses for a laser-plasma radiation source in the extreme ultraviolet range

Cited by 24 publications

References 3 publications

Expansion and Fragmentation of a Liquid-Metal Droplet by a Short Laser Pulse

Expansion and Fragmentation of a Liquid-Metal Droplet by a Short Laser Pulse

Expansion Dynamics after Laser-Induced Cavitation in Liquid Tin Microdroplets

Stable droplet generator for a high brightness laser produced plasma extreme ultraviolet source

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