Abstract

The OMEGA Laser has been successfully used for implosion experiments of inertial fusion for the past decade. The number of useful direct-drive experiments are now limited due to the energy and uniformity of illumination at the target. The OMEGA laser in its current configuration has a 2.4-KJ maximum output at 0.7 ns in 24 beams with a 18-cm aperture. An upgrade will be made to the current laser that will increase the energy and beam number respectively to 30 KJ and 60 KJ. Each beam will increase in aperture to 30 cm, while the pulse will actually be composed of a 5-ns pulse followed by a 0.7-ns pulse. The two pulses will co-propagate down the same beamline with the long (foot) pulse in the central region while the short (main) pulse will propagate in an annulus surrounding the foot pulse.¹ As in the OMEGA laser, the radiation at 1054 nm will be frequency tripled to 351 nm with a pair of KDP crystals. A decision was made during the preliminary design process to place the frequency-conversion crystals in the laser bay (rather than directly on the target chamber). This placed stringent damage fluence requirements on the blue transport mirrors, which prompted development of 351-nm-high reflectors. A summary of the requirements for some of the 2000 optical elements which will be required by the OMEGA Upgrade, is given in Table 1.

© 1992 Optical Society of America