SUMMARYWe have designed a large optical gimbal mount that will be used on the Petawatt Project currently under construction on the Nova laser. These mounts are designed to hold and tilt 0 9 4 cm mirrors and gratings that will redirect the 060 cm beam through the Petawatt vacuum compressor. Lacking the commercial availability to house this size optic, we have engineered a large mirror mount with a high natural frequency (42 Hz), low self-weight deflection of the mirror (&46), and high positioning accuracy characteristics (c1 p a d using flexures and stepping motors). Analysis details and methodology are presented.

The engineering process of integrating the Petawatt ( lOI watts) laser system into the existing 30 kJ (UV) Nova laser at Lawrence Livermore National Laboratory (LLNL) is described in detail. The nanosecond-long, chii Petawatt laser pulse is initially generated in a separate master oscillator room and then injected into one of Nova's 10 bearnlines. There, the pulse is further amplified and enlarged to -$60 cm, temporally compressed under vacuum to ~500 fs using large diameter diffraction gratings, and then finally focused onto targets using a parabolic mirror. The major Petawatt components are physically large which created many significant engineering challenges in design, installation and implementation. These include the diffraction gratings and mirrors, vacuum compressor chamber, target chamber, and parabolic focusing mirror. Other Petawatt system components were also technically challenging and include: an injection beamline, transport spatial filters, laser diagnostics, alignment components, motor controls, interlocks, timing and synchronization systems, support structures, and vacuum systems. The entire Petawatt laser system was designed, fabricated, installed, and activated while the Nova laser continued its normal two-shift operation. This process required careful engineering and detailed planning to prevent experimental downtime and to complete the project on schedule.