William L. Nighan

Efficient XeCl(B) formation in an electron‐beam assisted Xe/HCl laser discharge

XeCl(B) formation processes are examined for conditions typical of a discharge‐excited laser using HCl as the chlorine donor. It is shown that vibrational excitation of HCl followed by dissociative attachment is a primary step in the reaction sequence resulting in Cl− . XeCl(B) formation is the result of a three‐body Xe+ ‐CL− recombination reaction. Experimental results are presented which demonstrate efficient (∼2%) XeCl laser operation in an e‐beam assisted discharge in which over 75% of the energy was deposited by the discharge.

Kinetic processes in the electrically excited mercuric‐bromide dissociation laser

This letter reports the results of an analysis of basic kinetic and plasma processes in fast‐pulse (∼100 nsec) electric discharges containing mixtures of the mercuric‐bromide molecule, HgBr2, and N2 in a Ne background. Formation of the laser molecule HgBr (B2Σ+) is shown to occur as a result of dissociative excitation transfer following quenching of N2 (A3Σ+u ) by HgBr2.

Kinetic processes in the HgBr(B→X)/HgBr2 dissociation laser

Results are reported of an investigation of fundamental kinetic processes influencing discharge and laser properties typical of the 502‐nm HgBr(B→X)/HgBr2 dissociation laser. Specific attention is focused on conditions representative of electron‐beam‐controlled discharges. Experimental results and corresponding analysis and interpretation are presented for several laser mixtures, focusing particularly on the factors affecting discharge characteristics and HgBr(B) formation. A set of phenomenological electron‐HgBr2 cross sections inferred on the basis of analysis of experimental observations is presented, along with a discussion of the effect of electron‐electron collisions on medium properties at the level of fractional ionization typical of the HgBr(B)/HgBr2 laser.

Efficient HgBr (B→X) laser oscillation in electron‐beam‐controlled‐discharge‐excited Xe/HgBr2 mixtures

This letter reports the results of an investigation of HgBr(B2J+→X2J+) laser oscillation at 502 nm in Xe‐HgBr2 mixtures excited using an electron‐beam‐controlled discharge. Measured values of instantaneous electrical‐optical energy conversion efficiency were 2%, a level substantially higher than that typical of N2‐HgBr2 mixtures. Calculations show that efficiencies of 5–10% may be possible under optimized conditions.

Instability onset in electron‐beam‐sustained KrF* laser discharges

Measurements of instability onset in a spatially uniform electron‐beam‐sustained KrF* laser discharge have shown that the time at which instability occurs decreases from about 1 to 0.1 μsec as E/n is increased in the range required for efficient laser operation. This finding is in good agreement with computed ionization instability onset times determined on the basis of a comprehensive model of the discharge.

Stability enhancement in electron-beam-sustained excimer laser discharges

Techniques are described for prolonging the duration of stable e‐beam‐controlled excimer laser discharges, including: temporal tailoring of either the discharge voltage or the ionization source and kinetics modification by way of additives. Theoretical and experimental results are presented for KrF* laser discharges.

Influence of molecular dissociation and degree of ionization on rare gas–halide laser properties

The influence of F2 dissociation and the accompanying increase in fractional ionization is examined for conditions typical of electron‐beam‐sustained KrF* lasers. It is found that for electron‐density–F2‐density ratios greater than about 10−3, rare‐gas metastable loss due to electron excitation of higher levels begins to compete significantly with metastable‐F2 reactions, thereby leading to a substantial reduction in rare gas–halide production efficiency.