Speaker
Dr
Andrei Simakov
(Los Alamos National Laboratory)
Description
Low-mode implosion asymmetry and hydrodynamic instabilities of the capsule are considered the main obstacles for achieving ignition in indirect drive inertial confinement fusion (ICF). Superior ablation properties of beryllium (Be) ablators as compared with plastic and diamond ablators may help overcome these obstacles. In particular, higher Be ablation pressure permits use of either thicker fuel layers and thereby lower ICF capsule convergence; or of lower radiation drive temperatures and thereby larger hohlraums and case-to-capsule ratios. Both effects are predicted to be beneficial for implosion symmetry. Higher ablation velocity can provide enhanced ablation front stabilization and reduce detrimental effects of hydrodynamic instabilities. "High-foot" plastic campaign on the National Ignition Facility (NIF) has demonstrated importance of the suppression of instabilities, in particular by reducing the perturbation induced by the capsule support membranes that hold the capsule in the hohlraum - a major factor degrading earlier implosions. Initial measurements using hydro-growth radiography have shown that Be ablators are even more stable. In addition, high-adiabat Be implosions in 5.75 mm hohlraums with high-density (1.6 mg/cm^3) helium gas fill showed that performances of Be and comparable plastic targets were similar. Difficult-to-model non-linear plasma physics effects strongly degrade X-ray drive properties and the capsule implosion symmetry in such high-fill hohlraums. To fully test the predicted Be ablator advantages, hohlraums where such effects are suppressed need to be used. Beryllium integrated hohlraum experiments that started in the Fall of 2015 have been using larger (6.72 mm) hohlraums with lower (<0.6 mg/cm^3) fill densities and purposely reduced radiation drive temperature, and have demonstrated significantly improved laser-capsule coupling and good Be ablator performance. This suggests a future possibility of using even larger hohlraums to control symmetry if necessary. We will next employ these well-performing hohlraums with the goal of obtaining Be capsule implosions with good in-flight and stagnation symmetry.
| Country or International Organization | U.S. A. |
|---|---|
| Paper Number | IFE/P5-7 |
Primary author
Dr
Andrei Simakov
(Los Alamos National Laboratory)
Co-authors
Dr
Abbas Nikroo
(Lawrence Livermore National Laboratory)
Dr
Alex Zylstra
(Los Alamos National Laboratory)
Dr
Andrew MacPhee
(Lawrence Livermore National Laboratory)
Dr
Bernard Kozioziemski
(Lawrence Livermore National Laboratory)
Dr
Bruce Hammel
(Lawrence Livermore National Laboratory)
Dr
Craig Alford
(Lawrence Livermore National Laboratory)
Dr
Daniel Clark
(Lawrence Livermore National Laboratory)
Dr
David Strozzi
(Lawrence Livermore National Laboratory)
Dr
Debra Callahan
(Lawrence Livermore National Laboratory)
Dr
Denise Hinkel
(Lawrence Livermore National Laboratory)
Dr
Denise Hoover
(General Atomics)
Dr
Douglas Wilson
(Los Alamos National Laboratory)
Dr
Eduard Dewald
(Lawrence Livermore National Laboratory)
Dr
George Kyrala
(Los Alamos National Laboratory)
Dr
H. Xu
(General Atomics)
Dr
Haibo Huang
(General Atomics)
Dr
Hans Rinderknecht
(Lawrence Livermore National Laboratory)
Dr
Harry Robey
(Lawrence Livermore National Laboratory)
Hong Sio
(Massachusetts Institute of Technology)
Dr
James Rygg
(Lawrence Livermore National Laboratory)
Dr
Jay Salmonson
(Lawrence Livermore National Laboratory)
Dr
John Kline
(Los Alamos National Laboratory)
Dr
Jose Milovich
(Lawrence Livermore National Laboratory)
Dr
Joseph Ralph
(Lawrence Livermore National Laboratory)
Dr
Kelly Youngblood
(General Atomics)
Dr
Marilyn Schneider
(Lawrence Livermore National Laboratory)
Dr
Michael Edwards
(Lawrence Livermore National Laboratory)
Dr
Michael Marinak
(Lawrence Livermore National Laboratory)
Dr
Michael Stadermann
(Lawrence Livermore National Laboratory)
Dr
Neal Rice
(General Atomics)
Dr
Omar Hurricane
(Lawrence Livermore National Laboratory)
Dr
Peter Celliers
(Lawrence Livermore National Laboratory)
Dr
Praveshkumar Patel
(Lawrence Livermore National Laboratory)
Dr
Riccardo Tommasini
(Lawrence Livermore National Laboratory)
Dr
Richard Olson
(Los Alamos National Laboratory)
Dr
Salmaan Baxamusa
(Lawrence Livermore National Laboratory)
Dr
Shahab Khan
(Lawrence Livermore National Laboratory)
Dr
Steven Batha
(Los Alamos National Laboratory)
Dr
Steven Haan
(Lawrence Livermore National Laboratory)
Dr
Sunghwan Yi
(Los Alamos National Laboratory)
Dr
Tammy Ma
(Lawrence Livermore National Laboratory)
Dr
Theodore Perry
(Los Alamos National Laboratory)
Dr
Yi-Ming Wang
(Lawrence Livermore National Laboratory)
