December 7, 2021 @ 3:00 pm - 5:00 pm
Join us for a seminar with Mark J. Schmitt of Los Alamos National Laboratory, titled “The Quest for Inertial Confinement Fusion using Large Directly Driven Targets with 1, 2 or 3 Concentric Shells”.
The seminar will begin at 3pm ET on December 7, 2021.
Please contact Rachel Wise for connection information.
Recent progress has been made assessing the use of large directly-driven spherical targets consisting of 1, 2 or 3 shells to achieve ignition on the NIF using both single shell and double shell polar direct drive (PDD) implosions. The fundamental goals of these experiments is to validate the outer ablator shell hydro-efficiency, kinetic energy transfer efficiency between concentric shells, and adequate drive symmetry to compress the inner DT fuel. It is shown that large capsules driven at low intensity with the existing NIF laser can provide an extremely high coupling efficiency to the target with virtually no degradation from laser-plasma instabilities. For example, the Revolver triple-shell ignition target requires high (>90%) coupling of direct-drive laser energy to its large 5-6 mm outer shell to demonstrate high hydro-efficiency (~10%) of PDD laser energy into inward kinetic energy for small laser-beam-to-capsule radius ratios (~1/3). Moreover, high implosion kinetic energy transfer efficiency between the outer two colliding shells (>50%) is needed. Recent experiments employing 5 mm outer shells were measured using both x-ray self-emission imaging and x-ray backlit radiography. The post-collision inner shell trajectory was measured with backlighting showing good agreement with simulation. Diagnostic measurements indicate scattered light levels less than 2%. More recently, simulations of large single shell target using a similar polar direct drive configuration to ablate mainly the liquid DT fuel to drive the implosion have shown nuclear yields approaching 100 MJ for laser drive energies of 1.5 MJ. Details of these concepts will be discussed.
Research supported under LANL’s LDRD Program projects 20180051DR, 20200765ER and the US Department of Energy under contract 89233218CNA000001.
Dr. Schmitt received his PhD from UCLA and is currently a staff member in the Plasma Theory and Applications Group of the Computational Physics Division at Los Alamos National Laboratory. Mark has a broad background in the simulation of laser related applications including inertial confinement fusion (ICF), free-electron lasers (FELs), laser-plasma instabilities, short-pulse laser ion generation, laser-induced plasma discharge channels, laser-driven flyer plates, laser propagation and laser remote sensing. He most recently was the Principle Investigator for the Revolver direct-drive triple-shell project and the current polar direct drive double shell experiments on National Ignition Facility (NIF). Over his career at Los Alamos he has held many technical leadership roles for multi-disciplinary teams including projects to design high-power FELs, laser remote sensing systems, and ICF implosion experiments at both the Omega laser and the NIF. His ICF team executed the largest Be capsule implosions on NIF, conducted the first direct-drive CH capsule implosions on NIF, obtained the first 2D backlit images of direct-drive capsules on NIF and were the first to perform polar direct drive implosions of double shell targets on the NIF. Mark has mentored many students and post-docs during his tenure at LANL. He is a member of the APS and the Eta Kappa Nu Honor Society and is a Senior Member of the IEEE. He has well over 100 publications.