Molecular-dynamics study of ablation of solids under femtosecond laser pulses
Bibliographic record
Abstract
The ablation of solids under femtosecond laser pulses is studied using a two-dimensional molecular-dynamics model. The simulations show that different expansion regimes develop as a function of the injected energy. The origin of these regimes lies in changes of the thermodynamical relaxation path the material follows when the intensity of the laser increases. The shape of the pressure waves generated as a result of the absorption of the pulse is shown to vary from bipolar at low fluence to unipolar at high fluence, as a result of the decrease of the tensile strength of the material with temperature. By combining these results with an analysis of the thermodynamical trajectories for different portions of the target, we show that four different mechanisms can account for ablation at fluences below the threshold for plasma formation, namely spallation, phase explosion, fragmentation, and vaporization. These mechanisms are characterized in detail; it is demonstrated that they can occur simultaneously in different parts of the target.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".