ABSTRACT
On the Nova Laser at LLNL, we have demonstrated many of the key elements required for assuring that the next laser, the National Ignition Facility (NIF) will drive an Inertial Confinement Fusion (ICF) target to ignition. The indirect drive (sometimes referred to as “radiation drive”) approach converts laser light to x-rays inside a gold cylinder, which then act as an x-ray “oven” (called a hohlraum) to drive the fusion capsule in its center. On Nova a good understanding has been developed of the temperatures reached in hohlraums and of the ways to control the uniformity of the x-rays driving the spherical fusion capsules. Here we will review the physics of these laser heated hohlraums, recent attempts at optimizing their performance, and then return to the ICF problem in particular to discuss scaling of ICF gain with scale size, and compare indirect with direct drive gain.
