Numerical and theoretical study of the generation of extreme ultraviolet radiation by relativistic laser interaction with a grating
Bibliographic record
Abstract
The generation of harmonics by the interaction of a femtosecond, relativistic intensity laser pulse with a grating of subwavelength periodicity was studied numerically and theoretically. For normal incidence, strong, coherent emission at the wavelength of the grating period and its harmonics is obtained, nearly parallel to the target surface, due to relativistic electron bunches emanating from each protuberance. For oblique incidence (30°), only even harmonics of the grating periodicity are seen, but with an even higher intensity. This is due to constructive interference of the emission from the grating protuberances. The emission along the grating surface is composed of trains of attosecond pulses; therefore there is no need to use a filter. An efficiency greater than 10−4 is obtained for the 24th harmonic. The conversion efficiency is fairly constant when the similarity parameter S=ne/(a0nc)(∝neλL/IL1/2) is held fixed, and is optimum when S≃4. Here, ne and nc are the electron density and the critical density; a0=eEL/(meωLc) is the quiver momentum in the laser field EL normalized to mec.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".