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Electron impact ionization by drifting electrons in weakly ionized plasmas
L Conde1, L F Ibáñez, C Ferro-Fontán
1Departamento de Física Aplicada, E.T.S. Ingenieros Aeronáuticos, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 3, 2001
Summary
Electron drift significantly enhances ionization rates, increasing them by orders of magnitude. This localized ionization occurs faster than previously predicted, aligning with experimental plasma observations.
Area of Science:
- Plasma Physics
- Atomic and Molecular Physics
Background:
- Electron impact ionization is crucial for understanding plasma behavior.
- Previous models often assumed non-drifting electron populations, limiting applicability to certain plasma conditions.
Purpose of the Study:
- To derive an expression for the electron impact ionization rate considering drifting Maxwellian electrons.
- To quantify the impact of electron drift velocity on ionization rates.
- To compare theoretical predictions with experimental findings in specific plasma structures.
Main Methods:
- Derivation of the electron impact ionization rate expression for drifting Maxwellian electrons.
- Analysis of ionization rate variations with electron temperature and drift speed.
- Comparison of derived results with experimental data for plasma double layers and sheaths.
Main Results:
- Electron drift speeds of 1-5 times electron thermal velocity increase ionization rates by 2-7 orders of magnitude.
- Localized ionization occurs over shorter distances for drifting electrons compared to non-drifting ones.
- The derived model shows agreement with experimental observations in ionizing plasma double layers and electron-attracting sheaths.
Conclusions:
- Electron drift is a critical factor significantly amplifying ionization rates in plasmas.
- The derived ionization rate expression provides a more accurate model for drifting plasma environments.
- This work validates theoretical predictions against experimental evidence, enhancing plasma modeling capabilities.