Production of photoionized plasmas by the interaction of short FEL pulses with gaseous medium
Bibliographic record
Abstract
Photoionized plasmas created in the interaction of short linearly polarized x-ray pulses with a gaseous medium are characterized and discussed in the context of experiments with femtosecond FEL pulses. The electron distribution function in these plasmas remains strongly anisotropic due to unique plasma atomic and kinetic processes until such time that electron-electron collisions are able to thermalize the distribution. The relaxation of nonequilibrium photoionized plasmas is studied by using Monte-Carlo simulations which account for photoabsorption, elastic electron collisions, impact ionization of atoms, and atomic excitations. The dispersion properties and instabilities of a fully ionized x-ray-produced plasma is described. The photoionized plasma is found to be subject to a two-stream type of instability which has a growth rate comparable in magnitude to the plasma frequency and is therefore expected to have a dramatic effect on the evolution of the plasma. We performed 3D PIC simulation of this photo-ionization two-stream (PITS) instability. A model for electromagnetic field generation and emission resulting from the interaction of a short x-ray laser pulse with a gas jet is proposed. This is used to explore the effect of the thermo-EMF at the edge of a plasma characterized by an anisotropic electron energy distribution which results from the photoionization of the gas. Terahertz pulse generation from the plasma is predicted.
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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 | 0.001 |
| 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".