Argus laser system: performance summary

Abstract

The Argus Nd:glass laser system, presently operating as an experimental facility for laser fusion experiments, is described. The laser consists of a master oscillator and two identical amplifier chains, each of 20-cm output aperture. Argus is presently capable of delivering more than 4 TW of power in short (<100-psec) pulses, or more than 2 kJ of energy in 1-nsec pulses, to 100-microm targets. Short pulse performance enhancement obtained by increased aperture filling and implementation of image relaying with high power vacuum spatial filters is described. Experimentally recorded near-field and far-field data for several power levels are presented and discussed in terms of the limiting effects of nonlinear beam instabilities upon focal spot intensity.

Light propagation through large laser systems

“…(The dashed line represents the output power if nothing was lost in the spatial filters.) This curve agrees well with observed results [17] . More importantly, when applied to an actual pulse that would produce 1.6 TW with linear power transfer, the computed power versus time curve agrees strikingly with that measured on an experimental shot [ Fig.…”

“…The major impact of this "image relaying" scheme was to enable more effective filling of the available amplifier apertures. When partially implemented on Argus [17] , the immediate result was an approximate doubling of both the filling factor (defined as the ratio of the power carried by a smooth-profiie beam of diameter D to the power in a flat-profiled beam of the same maximum intensity and diameter) and the power on target. This scheme also suppressed the growth of small-scale modulation, as was later realized [ 191. With the Inertial Confinement Fusion Program emphasis shifting toward the use of longer and more energetic pulses for fusion target experiments, beam damage to optical components, particularly those with dielectriccoated surfaces, became the paramount limitation to system performance.…”

Performance of Shiva as a laser fusion irradiation facility

“…The current series of facilities began with the Janus Facility in 1974,--' progressed through the Argus (2) Facility in 1976/ ' has now reached Shiva and will continue with (2) Nova ' in 1983 which will provide the capability to reach scientific breakeven. Our work with Shiva has concentrated on experiments with ablatively driven targets since this is the path which leads to the high fue 1 ,r necessary to reach thermonuclear ignition.…”

High-power pulsed lasers

“…These stages are then assembled to make a laser system. 15 ~ 10 rad. Such a system optimization emphas'zes small-diameter, high-gain amplifiers, thin optical materials, and short systems.…”