Electron energy deposition in an electron-beam pumped KrF amplifier: Impact of the gas composition
Abstract
Calculations for electron deposition in electron beam generated KrF laser at atmospheric pressure have been performed. The impact of the Ar/Kr/F2 gas mixture on the electron energy distribution function, electron density, and mean energy, energy per electron-ion pair, attachment, dissociation, excitation, and ionization rates have been investigated. The F2 abundance controls the low energy (≲9 eV) component of the distribution function, while both the fluorine and krypton mole fraction affect the distribution in the midenergy domain (9 to ∼25 eV). Consequently, the F2 attachment rate coefficient varies with the F2 mole fraction (xF2) such that the electron density scales as 1/xF20.7. The rate coefficient for direct dissociation of F2 is smaller than for attachment but the former contributes more to the total power dissipation (∼8% at xF2=0.01). The excitation-to-ionization ratio for Kr is not constant, as generally assumed, but increases by a factor of two with a decrease in either the Kr or F2 abundance. Combining the former and present investigations leads to a set of fitting formulas to be used in beam kinetics codes for various collision rates as a function of both the electron beam power density and the composition.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- August 2002
- DOI:
- 10.1063/1.1491592
- Bibcode:
- 2002JAP....92.1200G
- Keywords:
-
- Atmospheric Pressure;
- Dissociation;
- Electron Beams;
- Electron Density (Concentration);
- Electron Energy;
- Electron Impact;
- Energy Transfer;
- Excimer Lasers;
- Gas Composition;
- Gas Mixtures;
- Ionization;
- Krypton;
- Laser Outputs;
- Laser Pumping;
- Lasers;
- Rare Gas Compounds;
- 42.55.Lt;
- 42.60.By;
- 42.55.Ah;
- 34.80.Gs;
- 34.80.Ht;
- 42.60.Lh;
- Lasers and Masers;
- Gas lasers including excimer and metal-vapor lasers;
- Design of specific laser systems;
- General laser theory;
- Molecular excitation and ionization by electron impact;
- Dissociation and dissociative attachment by electron impact;
- Efficiency stability gain and other operational parameters