Potential jump on a laser target

Bykovskii, Yurii A; Konyukhov, I Yu; Peklenkov, V. D.

doi:10.1070/qe2001v031n01abeh001889

Cited by 3 publications

(1 citation statement)

References 10 publications

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“…Target current (TC) is a relatively unexplored phenomenum in the field of laser-matter interaction. The initial studies started in the late seventies [2,3] and continued in a patchy fashion across the following decades [4,5] until recently.…”

Section: Introductionmentioning

confidence: 99%

On the origin of negative target currents during laser ablation of polyethylene

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Krása

et al. 2018

EPJ Web of Conferences

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Abstract. The exposure of a target to a focused laser beam results in the occurrence of a time-varying current between the target itself and the grounded vacuum chamber. This current is composed by three distinct phases, namely the ignition phase, in which the laser pulse drives the electron emission, while electrons coming from the ground through the target holder balance the positive charge generated on the target. The active phase appears at post-pulse times and it is characterized by the presence of peaked structures in the time-resolved current, representing characteristics of the target composition. Lastly, the afterglow phase is determined by a current of electrons flowing from the target to the ground. During the active phase of the target current resulting from polymers ablation with an UV KrF laser, negative target current peaks are observed, whose origin is still unknown. We investigate the dependence of these current structures on the dimensions of the target, using ultra-high molecular weight polyethylene disks of different thickness.

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Section: Introductionmentioning

confidence: 99%

On the origin of negative target currents during laser ablation of polyethylene

Side

Caricato

Krása

et al. 2018

EPJ Web of Conferences

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Energy and dose characteristics of ion bombardment during pulsed laser deposition of thin films under pulsed electric field

Fominski¹,

Nevolin²,

Smurov

2004

Journal of Applied Physics

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Experiments on pulsed laser deposition of Fe films on Si substrates were performed with the aim to analyze the role of factors determining the formation of an energy spectrum and a dose of ions bombarding the film in strong pulsed electric fields. The amplitude of the high-voltage pulse (−40kV) applied to the substrate and the laser fluence at the Fe target were fixed during the deposition. Owing to the high laser fluence (8J∕cm2) at a relatively low power (20mJ), the ionization of the laser plume was high, but the Fe vapor pressure near the substrate was low enough to avoid arcing. Electric signals from a target exposed to laser radiation were measured under different conditions (at different delay times) of application of electric pulses. The Si(100) substrates were analyzed using Rutherford ion backscattering∕channeling spectrometry. The ion implantation dose occurred to be the highest if the high-voltage pulse was applied at a moment of time when the ion component of the plume approached the substrate. In this case, the implanted ions had the highest energy determined by the amplitude of the electric pulse. An advance or delay in applying a high-voltage pulse caused the ion dose and energy to decrease. A physical model incorporating three possible modes of ion implantation was proposed for the interpretation of the experimental results. If a laser plume was formed in the external field, ions were accelerated from the front of the dense plasma, and the ion current depended on the gas-dynamic expansion of the plume. The application of a high-voltage pulse, at the instant when the front approached the substrate, maintained the mode that was characteristic of the traditional plasma immersion ion implantation, and the ion current was governed by the dynamics of the plasma sheath in the substrate-to-target gap. In the case of an extremely late application of a high-voltage pulse, ions retained in the entire volume of the experimental chamber (as a result of the laser-plume expansion) are involved in the implantation process. Therefore, the spread in implanted-ion energies depends on the configuration of the electric field inside the chamber.

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