Oscillator performance and energy extraction from a KrF laser pumped by a high-intensity relativistic electron beam

A laser cell with 21 of excitation volume was used to study the electron-beam pumped KrF laser system at excitation rates of 1.8- 7.0 MW/cm
³
. The system was optimized as an oscillator for various mixtures of Ar, Kr, and F
2
at total pressures of 1000 and 2500 torr. The resulting optimum conditions gave an intrinsic efficiency (laser energy out/electron-beam energy deposited) of 12 percent for the 1000 torr total pressure mixture with an output energy of 11 J/1. An efficiency of 10 percent with an output of 40 J/1 was obtained for the 2500 torr mixture. The system was then used as an amplifier to measure the extracted power as a function of input power for the two mixtures. The small-signal gain go, the nonsaturable absorption α, and the saturation intensity I
s
were determined for the two mixtures. Analysis of the data gave g
0
= 16-18 percent/cm,
\alpha = 0.75-1.25
percent/cm, and I
s
= 2 MW/cm
²
for the 1000 torr mixture and g
0
= 17-19 percent/cm,
\alpha = 1.0-1.5
percent/cm, and
I_{s} = 9
MW/cm
²
for the 2500 torr mix.