Nova symmetry: Experiments, modeling, and interpretation (HLP3 and HLP4)

Understanding and controlling capsule implosion symmetry is a key requirement for inertial confinement fusion (ICF). Symmetry was specifically called out in the Nova Technical Contract (NTC) as the HLP4 task. Later, elements of HLP3 were expanded to include symmetry work. For nearly a decade and a half it has been recognized that the fundamental asymmetry in a laser-heated hohlraum is a long-wavelength pole-waist radiation flux variation that varies like the P{sub 2} Legendre polynomial. It has also been recognized that one can control this asymmetry and achieve nearly symmetric implosions by appropriately pointing the laser beams.