The Role of Secular (Non-Exponential) Growth Caused by Mass Modulations in Inertial Confinement Fusion Implosions*

It is well understood that nonuniformity seeds are amplified due to Rayleigh–Taylor (RT) instability developed during shell acceleration in inertial confinement fusion (ICF) implosions. If the perturbation amplitude a is sufficiently small (a < 0.1λ, where λ is the perturbation wavelength), the perturbations grow exponentially with the growth rate dependent on λ. In addition, because of finite shell thickness, developed modulation in shell areal density leads to modulation in acceleration g̃ across the shell. This results in an additional g̃t2 or secular growth,[1] which affects the amplitude of the exponentially growing mode. This talk will review the role of secular growth in ICF implosions and highlight a path for more-robust target designs.