M. Matoba

The LEKKO VIII CO 2 gas laser system

The eight-beam CO 2 laser system, LEKKO VIII, producing 10 kJ for the inertial confinement fusion (ICF) research, has been completed. Advanced techniques developed with the LEKKO II 1 kJ laser have been fully implemented; such as a new type of laser gas, suppression of parasitic oscillation, and automatic operation of the system. A concept for a 100 kJ laser is examined as a feasible module design for a 1 MJ system.

Investigations of laser fusion by CO 2 laser

Experiments on laser plasma interaction using a COz laser (wavelength 10.6 pm) give us detailed information on the interaction mechanisms. The feasibility of laser fusion is going to require high power COz lasers. For this purpose we have been developing a high power E-beam controlled COz laser system with 200 J output in one nsec and a double discharge COz laser of 100 J in 100 nsec. For the former, to improve the energy extraction we have made a two band, multiline TEA laser oscillator and also investigated the high pressure ( 15 atm) &-beam C 0 2 laser oscillator. The E-beam controlled COz laser system consists of the following parts: oscillator, with Ge acoustooptical mode locker in the cavity; GaAs optical shutter combined with Ge polarizer to select one pulse from the mode-locked pulse train, or to chop out a pulse of nsec duration from Q-switched pulse; pre-amplifier ; E-beam Fig. 1. Variation of reflectivity and velocity spread of blow-off plasma against incident laser intensity.