Time-dependent collisional radiative model for helium
Bibliographic record
Abstract
Summary form only given. We perform numerical simulations of a helium discharge subjected to a fast-varying excitation source with a fully time-dependent 0-dimensional collisional radiative model (CRM). The model includes the Boltzmann equation (BE) for describing the electron kinetics, a set of rate equations for determining the populations of 31 energy levels of atomic helium, and accounts for the densities of atomic and molecular ions as well as of the helium excimer. All processes involving electrons (ionization, recombination, excitation, superelastic and elastic collisions, effective ambipolar diffusion, etc.) are dealt with in a fully kinetic way. The model also includes radiation trapping and a self-consistent gas temperature calculation.The novelty of this model is to include a large number of processes and species while solving the electron BE in a fully time-dependent way. Indeed, most of the existing CRMs for helium are either fluid models, time-independent kinetic models1, include the kinetic effects in an approximate way2, or just don't take into account such a large variety of processes and of excited states3. We illustrate the results of our model for the case of gaseous helium subjected to a powerful nanosecond excitation source. In such conditions the plasma is strongly out of equilibrium and shows properties much different than those of usual equilibrium plasmas. The afterglow stage also shows remarkable features, such as a high metastable atom proportion, which can be exploited for specific applications.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".