Plasma induced smoothing of a spatially incoherent laser beam and reduction of backward stimulated Brillouin scattering
Bibliographic record
Abstract
The angular divergence and spectral bandwidth of a spatially incoherent laser beam propagating in an underdense plasma are shown to correspond to additional spatial and temporal incoherence in the regime where the average laser intensity in a speckle approaches the self-focusing threshold. The transverse and longitudinal sizes of laser speckles inside the plasma are related in a way that makes it possible to define a local effective beam f-number. The effective f-number decreases as light propagates through the plasma, and the effective f-number at the outgoing boundary is consistent with the transmitted light angular spreading. The spectral broadening and red shift of the transmitted light are interpreted as a result of multiple near-forward stimulated Brillouin scattering of the propagating laser beam. The reduction of backward stimulated Brillouin scattering follows from decrease of the effective speckle length and from the plasma induced temporal incoherence.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".