Accelerated Expansion of Laser-Ablated Materials near a Solid Surface

Chen, Kuan-Ren; Leboeuf, J. N.; Wood, R. F.; Geohegan, David B.; Donato, J. M.; Liu, C. L.; Puretzky, Alexander A.

doi:10.1103/physrevlett.75.4706

Cited by 59 publications

(33 citation statements)

References 11 publications

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“…After 100 ns, the velocity rapidly falls to values below 1 km/s. These values are consistent with experimental measurements by ourselves and others [12][13][14]. Figure 6.…”

Section: Modeling Resultssupporting

confidence: 82%

“…Recombination rates are relatively slow during the later stages of plume expansion, and are modeled using a rate equation instead of assuming ionization equilibrium [15]: (14) where x=n e /n is the degree of ionization, x eq is the equilibrium ionization given by the Saha equation, and b is the rate constant (a function of n and T).…”

Section: Model Descriptionmentioning

confidence: 99%

“…During the expansion stage, the plume front can achieve very high velocities. For example, the expansion velocity obtained with a laser intensity of 10 9 W/cm 2 can easily reach 10 8 cm/s, corresponding to a directed kinetic energy greater than 1 keV [12][13][14]. Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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The effect of ionization on cluster formation in laser ablation plumes

Tillack

Blair²,

Harilal³

2004

Nanotechnology

118

104

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Ablation plumes caused by short-pulse laser irradiation provide conditions which are well suited to the formation of nanoclusters. The high saturation ratios and presence of ionization lead to extraordinarily high nucleation rates and small critical radii. We have explored the homogeneous nucleation and heterogeneous growth of condensate from Si targets expanding into a low-pressure He ambient using a Nd:YAG laser with pulse length of 8 ns, wavelength of 532 nm and intensities in the range of 5¥10 7 to 5¥10 9 W/cm 2 . Clusters in the range of 5-50 nm have been produced. In the highly dynamic, non-linear regime of short-pulse laser-matter interactions, plume evolution and condensation processes are strongly coupled and difficult to predict accurately from modeling alone. Both numerical predictions and experimental results were used to quantify the competing effects of ionization and supersaturation. The results suggest a dominant influence of ionization for nearly all intensities above the ablation threshold.

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“…After 100 ns, the velocity rapidly falls to values below 1 km/s. These values are consistent with experimental measurements by ourselves and others [12][13][14]. Figure 6.…”

Section: Modeling Resultssupporting

confidence: 82%

Section: Model Descriptionmentioning

confidence: 99%

See 1 more Smart Citation

The effect of ionization on cluster formation in laser ablation plumes

Tillack

Blair²,

Harilal³

2004

Nanotechnology

118

104

View full text Add to dashboard Cite

show abstract

“…Chen et al [17] reported that partial ionization of the vapour due to temperature increase near the shock wave front also can result in an acceleration of the flow. The addition of kinetic energy to the laser-induced flow through absorption of incident laser energy will result in a more moderate deceleration of the shockwave velocity than the predicted blastwave theory [18].…”

Section: Resultsmentioning

confidence: 99%

Plume splitting and sharpening in laser-produced aluminium plasma

Harilal

Bindhu

Tillack

et al. 2002

J. Phys. D: Appl. Phys.

127

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Plume splitting and sharpening were observed in laser-produced aluminium plasma created using 532 nm, 8 ns pulses from a frequency doubled Nd : YAG laser. Measurements were made using 2 ns gated fast photography as well as space and time resolved optical emission spectroscopy. The motion of the leading edge of the plume was studied with several background air pressures and the expansion of the plume front was compared with various expansion models. Combining imaging together with time resolved emission diagnostics, a triple structure of the plume was observed.

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“…This results in the redistribution of momentum and kinetic energy from the plume front back into the gas. In addition, unsteady, non-adiabatic processes (ionization and phase changes) initially may produce a greater than expected initial expansion of the leading edge of the gas (Chen et al, 1995) and could play a similar role here. Eventually adiabatic expansion controls expansion as the internal energy in the gas is converted to kinetic energy of expansion (along with lower densities and temperatures).…”

Section: Plume Evolutionmentioning

confidence: 93%

The Deep Impact oblique impact cratering experiment

Schultz

Eberhardy

Ernst

et al. 2007

Icarus

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The Deep Impact probe collided with 9P Tempel 1 at an angle of about 30 • from the horizontal. This impact angle produced an evolving ejecta flow field very similar to much smaller scale oblique-impact experiments in porous particulate targets in the laboratory. Similar features and phenomena include a decoupled vapor/dust plume at the earliest times, a pronounced downrange bias of the ejecta, an uprange "zone of avoidance" (ZoA), heart-shaped ejecta ray system (cardioid pattern), and a conical (but asymmetric) ejecta curtain. Departures from nominal cratering evolution, however, provide clues on the nature of the impact target. These departures include: fainter than expected flash at first contact, delayed emergence of the self-luminous vapor/dust plume, uprange-directed plume, narrow early-time uprange ray followed by a late-stage uprange plume, persistence of ejecta asymmetries (and the uprange ZoA) throughout the approach sequence, emergence of a downrange ZoA at late times, detachment of uprange curved rays, very long lasting non-radial ejecta rays, and high-angle ejecta plume lasting over the entire encounter. The first second of crater formation most closely resembles the consequences of a highly porous target, while later evolution indicates that the target may be layered as well. Experiments also reveal that impacts into highly porous targets produce a vapor/dust plume directed back up the incoming trajectory. This uprange plume is attributed to cavitation within a narrow penetration funnel. The observed lateral expansion speed of the initial vapor plume downrange provides an estimate for the total vaporized mass equal to ∼5m p (projectile masses) of water ice or 6m p of CO 2 . The downrange plume speed is consistent with the gas expansion added to the downrange horizontal component of the DI probe. Based on high-speed spectroscopy of experimental impacts, the observed delay in brightening of the DI plume may be the result of delayed condensation of carbon, in addition to silicates. Observed molecular species in the initial self-luminous vapor plume likely represent recombination products from completely dissociated target materials. The crater produced by the impact can be estimated from Earth-based observations of total ejected mass to be 130-220 m in diameter. This size range is consistent with a 220 m-diameter circular feature at the point of impact visible in highly processed, deconvolved HRI images. The final crater, however, may resemble an inverted sombrero-hat, with a deep central pit surrounded by a shallow excavation crater. Excavated distal material observed from the Earth was likely from the upper few meters contrasted with ballistic ejecta observed from the DI flyby, which included deep materials (10-30 m) within the diffuse plume above the crater and shallower (5-10 m) materials within the ejecta curtain.

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Accelerated Expansion of Laser-Ablated Materials near a Solid Surface

Cited by 59 publications

References 11 publications

The effect of ionization on cluster formation in laser ablation plumes

The effect of ionization on cluster formation in laser ablation plumes

Plume splitting and sharpening in laser-produced aluminium plasma

The Deep Impact oblique impact cratering experiment

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