First bromine doped cryogenic implosion at the National Ignition Facility

TL;DR

This study demonstrates the first use of bromine doping in cryogenic capsules at NIF to investigate nuclear reactions, showing significant impact on yield and potential for new diagnostic methods.

Contribution

Introduces bromine doping in cryogenic capsules at NIF and explores nuclear reactions on dopants as a diagnostic tool in inertial confinement fusion.

Findings

Bromine doping reduced DT yield by 2.6 times.

Detection of reaction products confirms nuclear reactions on dopants.

Nuclear reactions on dopants are feasible for diagnostics.

Abstract

We report on the first experiment dedicated to the study of nuclear reactions on dopants in a cryogenic capsule at the National Ignition Facility (NIF). This was accomplished using bromine doping in the inner layers of the CH ablator of a capsule identical to that used in the NIF shot N140520. The capsule was doped with 3$\times$10$^{16}$ bromine atoms. The doped capsule shot, N170730, resulted in a DT yield that was 2.6 times lower than the undoped equivalent. The Radiochemical Analysis of Gaseous Samples (RAGS) system was used to collect and detect $^{79}$Kr atoms resulting from energetic deuteron and proton ion reactions on $^{79}$Br. RAGS was also used to detect $^{13}$N produced dominantly by knock-on deuteron reactions on the $^{12}$C in the ablator. High-energy reaction-in-flight neutrons were detected via the $^{209}$Bi(n,4n)$^{206}$Bi reaction, using bismuth activation foils located 50 cm outside of the target capsule. The robustness of the RAGS signals suggest that the use of nuclear reactions on dopants as diagnostics is quite feasible.