Comparisons of ignition criteria and applications to double shell capsules*

In this work, we compare several ignition criteria currently in use for the NIF ignition capsules. Through the comparison, we identified the similarities and essential differences among the ignition conditions. We found that the double temperature requirement for achieving ignition, given by Lindl et al, is the strongest ignition condition. On the other hand, the condition, d²T/dt² > 0, given by Springer and by Hurricane et al is the weakest condition. We find that some ignition criteria do not ensure self-sustained thermonuclear (TN) burn. We then applied our double-energy requirement for ignition to the double-shell capsules and derived the necessary and sufficient conditions for double shell capsules to achieve self-sustained TN burn. The ignition threshold for double shell devices is slightly lower than the ignition criterion for both the NIF hot-spot ignition capsules and pushered single shell capsules because of the high fuel areal density in the double-shell capsules (LA-UR-24-26069).