Compression and Robust Burn in the Presence of Low-Mode Asymmetries for Double Shells

We previously reported a metric for robust burn in double shell implosions, where the specific power deposited by alpha heating must exceed the specific power due to expansion cooling losses of the hot spot [1]. This criterion results in a minimum hot spot temperature at stagnation in the absence of burn. Margin is obtained for designs by the degree that they exceed this minimum no-burn temperature. In this present work, we extend this model to include simple low-mode asymmetry using a quasi-adiabatic approximation, and compare predictions of this simple model to 2D xRAGE simulations of double shell capsules. We further examine the role that radiation losses, due to increased surface area of the fuel-pusher interface, play in failing to meet ignition conditions, and how one might place experimental bounds on that loss.