Systematic analysis of direct-drive baseline designs for shock ignition with the Laser MegaJoule

We present direct-drive target design studies for the laser Megajoule using two distinct initial aspect ratios (A = 34 and A = 5). Laser pulse shapes are optimized by a random walk method and drive power variations are used to cover a wide variety of implosion velocities between 260 km/s and 365 km/s. For selected implosion velocities and for each initial aspect ratio, scaled-target families are built in order to find self-ignition threshold. High-gain shock ignition is also investigated in the context of Laser MegaJoule for marginally igniting targets below their own self-ignition threshold. (authors)