Micro x-ray sources from femtosecond laser plasmas
Bibliographic record
Abstract
Ultrabright and ultrashort x-ray pulses may be used for time resolved studies of phase transitions in materials and potentially for x-ray microscopy applications. Through the interaction of high intensity ultrashort laser pulses (~100fs, 1015 -1017 W/cm2) with solid targets, high temperature and high density plasma is formed on the material surface. Electrons are accelerated in the plasma and multi keV x-rays are generated when they interact with the target material. Such hot electrons are produced from resonance absorption and other nonlinear interactions both at the solid density surface and in the underdense plasma. Initial experimental measurements of keV x-ray emission from microplasmas generated by 130fs, 800nm, 0.5mJ Ti:Sapphire laser pulses focused to intensities of ~1016 -1017 W/cm2 onto a solid target have been carried out. The keV x-ray emission has been characterized both in air and in vacuum. In particular, the scaling of x-ray conversion efficiency and the dependence on pulse energy, angle of incidence and pressure have been studied. The x-ray conversion efficiency improves through the use of a prepulse, indicating that the interactions in the underdense plasma also contribute to hot electron and keV x-ray generation.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.010 | 0.002 |
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".