Dynamics of multiple plumes in laser ablation: Modeling of the shielding effect

A simple experimental set-up is described to measure the electromagnetic shielding property of high Tc superconducting samples. Measurements were performed using HTSC materials in the form of laser ablated thin films, powders and sintered pellets. Samples used were Gd-123 in pure and doped form as well as a few Bi-based superconducting ceramics. For comparison, similar measurements were carried out on metals like aluminium, copper and μ metal. Very effective shielding was observed for HTSC materials compared to the conventional materials mentioned above. However it also depended on the sample types and poor shielding was observed for powdered HTSC material in comparison to thin films prepared by laser ablation.

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Laser Ablation Modeling of Periodic Pattern Formation on Polymer Substrates

Advanced Engineering Materials ◽

10.1002/adem.200700323 ◽

2008 ◽

Vol 10 (5) ◽

pp. 488-493 ◽

Cited By ~ 8

Author(s):

A. Lasagni ◽

M. Cornejo ◽

F. Lasagni ◽

F. Muecklich

Keyword(s):

Laser Ablation ◽

Pattern Formation ◽

Periodic Pattern ◽

Polymer Substrates ◽

Ablation Modeling

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Influence of the shielding effect on the formation of a micro-texture on the cermet with nanosecond pulsed laser ablation

Optics Letters ◽

10.1364/ol.43.001451 ◽

2018 ◽

Vol 43 (7) ◽

pp. 1451 ◽

Cited By ~ 5

Author(s):

Jiandong Yuan ◽

Liang Liang ◽

Lelun Jiang ◽

Xin Liu

Keyword(s):

Laser Ablation ◽

Pulsed Laser ◽

Pulsed Laser Ablation ◽

Shielding Effect ◽

Nanosecond Pulsed Laser

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Multi-Time Step Modeling of Plume Dynamics in Nanosecond-Scale Carbon Ablation

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.sw20 ◽

2008 ◽

Vol 8 (11) ◽

pp. 6075-6081

Author(s):

Kedar Pathak ◽

Alex Povitsky

Keyword(s):

Laser Ablation ◽

Laser Beam ◽

Computer Time ◽

Time Span ◽

Shielding Effect ◽

Incident Laser Beam ◽

Incident Laser ◽

Time Step ◽

Degree Of Ionization ◽

Plume Dynamics

The time span of plume dynamics in laser ablation of carbon ranges from nanoseconds to milliseconds. Multi-time step approach is developed to study the plume dynamics over this entire range with minimum requirements of numerical computational resources. This approach is applied to study one of the important aspects of nanosecond-scale laser ablation, namely the shielding of incident laser beam with previously ejected plumes. Capturing the shielding effect requires smaller than nanosecond-scale time step because of large velocity and pressure gradients in plume. Use of this time step over the entire domain needs enormous amount of computer time to cover the whole time span of plume dynamics. Multi-time step modeling for such an application is therefore useful. In general, for nanosecond-scale laser ablation this shielding is caused by ionized particles and by gas molecules. It is shown for carbon plume resulting from the nanosecond-scale lasers that the degree of ionization is small. Ionization of ablated carbon is estimated by Saha equation for the given initial plume conditions. The shielding of incident laser beam is therefore calculated by normal molecular absorption. The laser-light intensity that reaches the target for subsequent pulses is evaluated.

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