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Ablation of Solids by Powerful Short Pulse Lasers: Ablation Mechanisms, Thresholds and Rates
Professor Eugene Gamaly
Laser Physics Centre, Research School of Physical Science and Engineering, Australian National University
3.30pm, Friday 12 November 2004, AR103 Seminar Room, Graduate Research Centre
The transient ablation of solids by intense short laser pulses is described self-consistently as a
function of laser and material parameters. The relationship between pulse duration and times for electron-to-ion energy transfer,
heat conduction, and building-up of high-energy tail in Maxwellian distribution defines the domination of a particular ablation
mechanism that depends also on the average intensity per pulse (or temperature in the laser-heated surface layer). The path for
transition from non-equilibrium ablation to the thermal evaporation is found in the parameter space. The ablation depth and rate
are presented in an explicit scaling form as a function of laser and material parameters. We discuss the issue of the phase state
of the ablated vapors depending on the absorbed laser energy, and pulse duration, and present a condition for the full atomization
of vapors. The formulae for ablation depth and ablation rate, combining the laser and target parameters, are compared to
experimental data and to those for the equilibrium ablation by long pulses.
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