Suggestions of Instability Driven Mass Injection in Direct-Drive Cryogenic Implosion Experiments

We show that distinct signatures in both the acceleration and stagnation phases of direct-drive cryogenic implosion experiments are consistent with 3-D modeling that induces the jetting of a peripheral mass into the nascent hot spot. The cause of such jetting remains speculative, but a candidate is the role of intrinsic target features. The signatures arise due to the injection of dense fuel and ablator material into the low-density center during early stages of hot-spot formation. First, we show that the defect modeling creates an advance of hot-spot emission during the implosion history, such as has been observed and which is not accounted for by the model with imprinting. Second, we have found a reduction of the discrepancy when the ablation front is separated from the hot spot by increased cryogenic payload, providing strong support for an origin in ablation front instability. Lastly, we show that measurements used to infer ion and electron temperatures indicate an equilibration exceeding 1-D models, an expected result of the mass injection.