Electron-beam-irradiated discharges considered for initiating high-pressure pulsed chemical lasers

Volumetric irradiation by a short‐pulse electron beam has been used to trigger long‐duration spatially uniform electric discharges in gas mixtures of He and F₂ or SF₆. Uniform energy deposition to 300 J/liter has been observed for atmospheric F₂–He mixtures at nominal electron‐beam currents of 3 A/cm² and discharge currents up to 20 A/cm². Operation suitable for efficient initiation of pulsed HF/DF chain lasers appears possible over a wide range of E/N and mixture ratios, limited by breakdown at large E/N and negligible field enhancement at low E/N. Approximate analytical plasma models are presented and used in conjunction with time‐resolved afterglow current measurements to obtain rate constants for F⁻‐ion ${\mathrm{F}}_2^{+}-\mathrm{ion}$ recombination and ${\mathrm{F}}_2^{+}-\mathrm{ion}$ electron recombination. Estimates of F₂ dissociation fractions achieved in the experiments imply the possibility of scalable and efficient initiation of pulsed chemical lasers with such discharges.