Measurements of improved stability to achieve higher fuel compression in ICF
Author:
Do A.1ORCID, Casey D. T.1ORCID, Clark D. S.1ORCID, Bachmann B.1ORCID, Baker K. L.1ORCID, Braun T.1ORCID, Briggs T. M.1, Chapman T. D1ORCID, Celliers P. M.1ORCID, Chen H.1ORCID, Choate C.1, Dewald E. L.1ORCID, Divol L.1ORCID, Fathi G.1, Fittinghoff D. N.1ORCID, Hall G. N.1ORCID, Hartouni E.1ORCID, Holunga D. M.1ORCID, Khan S. F.1ORCID, Kritcher A. L.1ORCID, Landen O. L.1ORCID, MacPhee A. G.1ORCID, Millot M.1ORCID, Marley E. V.1, Milovich J. L.1ORCID, Nikroo A.1ORCID, Pak A. E.1, Schlossberg D. J.1ORCID, Smalyuk V. A.1, Stadermann M.1ORCID, Strozzi D. J.1ORCID, Tommasini R.1ORCID, Weber C. R.1ORCID, Woodworth B. N.1ORCID, Yanagisawa D. K.1, Birge N. W.2ORCID, Danly C. R.2ORCID, Durocher M.2ORCID, Freeman M. S.2ORCID, Geppert-Kleinrath H.2ORCID, Geppert-Kleinrath V.2ORCID, Kim Y.2ORCID, Meaney K. D2ORCID, Wilde C. H.2ORCID, Johnson M. Gatu3ORCID, Allen A.4ORCID, Ratledge M.4, Kong C.4ORCID, Fehrenbach T.5ORCID, Wild C.5ORCID
Affiliation:
1. Lawrence Livermore National Laboratory 1 , Livermore, California 95377, USA 2. Los Alamos National Laboratory 2 , Los Alamos, New Mexico 87545, USA 3. Massachusetts Institute of Technology 3 , Cambridge, Massachusetts 02139, USA 4. General Atomics 4 , San Diego, California 92121, USA 5. Diamond Materials GmbH 5 , Freiburg 79108, Germany
Abstract
While nuclear fusion ignition has been achieved at the National Ignition Facility in inertial confinement fusion (ICF) experiments, obtaining higher gain and more efficient burn is still desired. In that regard, increasing the compression of the fuel is an important factor. In recent indirect-drive capsule implosions, the SQ-n campaign is testing the hypothesis that reducing the hydrodynamic growth of perturbations is key to achieving higher compression of high-density carbon based-ablators for ICF. SQ-n uses a design at lower adiabat with a ramped foot laser pulse shape to minimize early-time hydrodynamic instability growth, predicted to be reduced by a factor of 10, and an optimized ablator dopant distribution. Subsets of experiments were conducted within the SQ-n campaign to study the implosion symmetry, laser backscatter, stability, and compression. Only the latter two will be reviewed here. Shock timing experiments using the velocity interferometer system for any reflector diagnostic enabled the development of a gently accelerating shock velocity. The ice–ablator interface acceleration, important for managing the Richtmyer–Meshkov phase growth, was observed with refraction enhanced radiography and the ablation front growth was measured using radiography of pre-imposed modulations. Finally, layered tritium-hydrogen-deuterium (∼75% H, ∼25% T, ∼2–10% D) and deuterium–tritium implosions demonstrate that between 15% ± 3% and 30% ± 6% improved compression has been achieved.
Funder
U.S. Department of Energy
Subject
Condensed Matter Physics
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