A multi petawatt high energy power chain is under construction at CEA-CESTA for the PETAL (PETawatt Aquitaine
Laser) project within the LIL facility. It requires an Nd: glass high energy Amplifier, with sixteen 757 mm x 402 mm
aperture laser slabs to increase the injected chirped pulse (44 mJ) up to 6.4 kJ. To take account of the PETAL project
requirements, optical, electrical, mechanical and cooling optimizations have been performed to design this amplifier
system, divided into two parts sized approximately 1.2 m x 1.2 m x 8m. The solutions adopted made it possible to
control the laser gain over the full aperture, to obtain a 15 μrad mechanical stability for each laser slab with predicted
vibratory PSD and approximately a 1 hour period for laser cooling.