A path to a hydro-equivalent ignition demonstration for laser direct-drive on the OMEGA laser
ORAL · Invited
Abstract
Laser direct drive (LDD) offers significant advantages in terms of target simplicity, improved energy coupling and large fuel masses over indirect drive. However, performance degradations from hydrodynamic and laser-plasma instabilities seeded and driven by the direct illumination pose limitations on the parameter space available for achieving ignition. Recent advances in target design and prediction capability using statistical modeling led to significant improvements in performance to achieve a Lawson triple product that hydrodynamically scales to about 90% of the value required for ignition if equivalent laser-target coupling is achieved at the 2 MJ energy level of the NIF. New design improvements are identified to forge a path forward for a hydro-equivalent ignition demonstration. The first is related to controlling the mode-1 asymmetry through a novel analysis that quantifies the individual contributions from target offset, laser mispointing, power imbalance and a residual systematic mode. It uses flow measurements, mode-1 simulations and statistical regressions over a large database of shots to determine the optimum target offset to be applied in the experiments to minimize mode-1 amplitude. The second improvement comes from cooling the ice layer below the triple point right before shot time. This leads to lower DT vapor densities and higher convergence. While subcooling is an effective way to increase areal density, it requires mitigation of mode 1 due to greater sensitivity to low modes. One implosion with 2.5K subcooling achieved record hot spot pressure. The third improvement comes from a new formulation of the statistical model (SM) used to accurately predict target performance directly from input parameters such as laser pulse shape and target specifications. This new SM formulation provides direct guidance on target dimensions and laser beam to target radius to achieve the highest performance on the OMEGA laser.
*This material is based upon work supported by the DOE [National Nuclear Security Administration] University of Rochester "National Inertial Confinement Fusion Program" under Award Number DE-NA0004144 and the Department of Energy (DOE) Office of Fusion Energy Sciencesunder Award Numbers DE-SC0022132, DE-SC0024456, DE-SC0024381.
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Presenters
Aarne Lees
University of Rochester - Laboratory for Laser Energetics
Laboratory for Laser Energetics, University of Rochester
University of Rochester
Authors
Aarne Lees
University of Rochester - Laboratory for Laser Energetics
Laboratory for Laser Energetics, University of Rochester
University of Rochester
Riccardo Betti
Laboratory for Laser Energetics, University of Rochester
Laboratory for Laser Energy, Rochester, NY, USA.
Varchas Gopalaswamy
Laboratory for Laser Energetics, University of Rochester
Laboratory for Laser Energetics - Rochester
James P Knauer
Laboratory for Laser Energetics, University of Rochester
University of Rochester
Luke A Ceurvorst
Laboratory for Laser Energetics, University of Rochester
University of Rochester
Dhrumir P Patel
University of Rochester
Pericles Silouanos Farmakis
Laboratory for Laser Energetics, University of Rochester
University of Rochester
Laboratory for Laser Energetics
Rahman Ejaz
Laboratory for Laser Energetics, University of Rochester
Ka Ming Woo
Laboratory for Laser Energetics, University of Rochester
Duc M Cao
Laboratory for Laser Energetics, University of Rochester
U. Rochester/LLE
Cliff A Thomas
University of Rochester
Laboratory for Laser Energetics, University of Rochester
Igor V Igumenshchev
Lab for Laser Energetics
P. B Radha
Los Alamos National Laboratory
University of Rochester
Kenneth S Anderson
Laboratory for Laser Energetics, University of Rochester
Timothy J Collins
Laboratory for Laser Energetics, University of Rochester
Valeri N Goncharov
Laboratory for Laser Energetics, University of Rochester
University of Rochester, Laboratory for Laser Energetics
Rahul C Shah
Laboratory for Laser Energetics - Rochester
University of Rochester - Laboratory for Laser Energetics
Laboratory for Laser Energetics, University of Rochester
Chad Forrest
Laboratory for Laser Energetics
Laboratory for Laser Energetics, University of Rochester
Christian Stoeckl
Laboratory for Laser Energetics, University of Rochester
University of Rochester
Vladimir Glebov
Lab for Laser Energetics
Dana H Edgell
University of Rochester - Laboratory for Laser Energetics
Michael J Rosenberg
University of Rochester Laboratory for Laser Energetics (LLE)
Laboratory for Laser Energetics, University of Rochester
University of Rochester
Kristen Churnetski
University of Rochester
Peter V Heuer
Laboratory for Laser Energetics
Sean P Regan
Laboratory for Laser Energetics, University of Rochester
Roger T Janezic
Laboratory for Laser Energetics, University of Rochester
David R Harding
University or Rochester Laboratory for Laser Energetics
Laboratory for Laser Energetics
Mark J Bonino
University or Rochester Laboratory for Laser Energetics
Laboratory for Laser Energetics, University of Rochester
Siddharth Sampat
Laboratory for Laser Energetics
Maria Gatu Johnson
Plasma Science and Fusion Center, Massachusetts Institute of Technology
