Radiochemical Signatures of Interfacial Areal Density and Mix in NIF Implosions

Recent experimental results from the Radiochemical Analysis of Gaseous Samples (RAGS) diagnostic facility fielded at the National Ignition Facility (NIF) have demonstrated $^{13}$N production from charged particle nuclear reactions. This radiochemical product is very sensitive to the fuel-ablator interface areal density. Two specific reactions dominate $^{13}$N production: $^{12}$C(d,n)$^{13}$N and $^{13}$C(p,n)$^{13}$N. The short range of the energetically up-scattered deuterons from the cold DT fuel layer restricts the production to the proximate ablator interface thus providing high sensitivity to the interfacial configuration. Although the proton-mediated reaction is almost equally favorable, the small natural abundance of $^{13}$C suppresses this contribution to $^{13}$N production. Representative HYDRA simulations are used to illustrate these observed effects.