Join us for a seminar with David Frost, McGill University, 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.

Abstract:

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. Bio: 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.

Join us for a seminar with David Frost, McGill University, titled “Enhanced Blast Pressure, Temperature, and Impulse from Metalized Explosive Fireballs”.

The seminar will begin at 3pm ET on November 2, 2021.

Please contact Rachel Wise for connection information.

Abstract:

Fireballs generated by metalized explosives are highly heterogenous, with large spatial variations in gas and particle density and temperature, and exhibit multiple internal wave interactions driven by particle jetting. For fuel-rich systems with high solid particle mass loading, there is insufficient oxidizing species in the detonation products, and the particles continue to burn as they move into the shocked air. For fuel-lean systems, early-time enhancement of the blast pressure suggests that a substantial fraction of the metal particles release their energy on the timescale of the detonation propagation (10s of microseconds), consistent with the early-time enhancement of metal acceleration in plate-push experiments using the same metalized explosive. Surprisingly, the blast augmentation due to particle energy release is not a systematic function of particle size, indicating that we need to completely rethink how the particles release their energy in the extreme conditions behind the detonation wave and within the detonation products. Other interesting effects result from the interaction of shock waves with the metalized fireball, particle collision and fragmentation, relative motion between the particles and gas, and the particular mode of combustion of different metals. I will illustrate some of the features of this complex multiphase reacting environment using a variety of experimental techniques, and highlight some of the outstanding issues that need to be resolved.

Bio: 

David Frost is currently a Professor in the Mechanical Engineering Department of McGill University in Montreal. This year he will be happy to finish his term as Associate Dean and reduce his Zoom-fatigue from innumerable Covid-related meetings. His research interests are in the areas of metal combustion, multiphase combustion processes and shock wave physics. He joined McGill after completing his PhD at Caltech where he studied the dynamics of explosive boiling at the superheat limit. Past projects have involved steam explosions due to molten metal/water interactions, bubble detonations, shock interactions with compressible materials, and the synthesis of ballistic ceramics. For the last few decades he has been studying the combustion of dust clouds and blast waves from metalized explosives. Everything he knows about metal combustion and optical diagnostics he learned from discussions with his great colleagues, including Sam Goroshin, Jeff Bergthorson, Nick Glumac, Mike Soo, among others, frequently over beer.

Writing Archival Papers K.T. Ramesh Alonzo G. Decker, Jr. Professor of Science and Engineering Department of Mechanical Engineering Johns Hopkins University

October 12, 2021 3-5 PM ET

Registration link This workshop focuses on the processes associated with the publication of archival journal papers within the scientific literature. We will discuss journals, editorial boards, reviewers; submission guidelines; how submitted papers are reviewed; and what reviewers and editors look for in papers.We will then discuss the mechanics of writing a paper (assuming the research has already been done). This includes the identification of the story that you want to tell, the typical structure of the journal paper, and the questions of authorship and plagiarism.

K.T. Ramesh, the Alonzo G. Decker, Jr. Professor of Science and Engineering at Johns Hopkins, is a leading authority in the areas of impact physics and the failure of materials under extreme conditions. Ramesh is a professor in the Department of Mechanical Engineering, and also holds joint appointments in the Department of Earth and Planetary Sciences and the Department of Materials Science and Engineering. He is the founding director of the Hopkins Extreme Materials Institute (HEMI), which develops science and technology to protect people, structures and the planet. HEMI brings together experts from Johns Hopkins’ Whiting School of Engineering, Krieger School of Arts and Sciences, and Applied Physics Laboratory, as well as scientists and engineers from the federal government, U.S. national laboratories, industry, and research institutions across the world.

Please register for this event here. Interested participants who do not register will not get sent the Zoom link required to attend the event.

Join us for a seminar with Dr. Jimmie Oxley, University of Rhode Island, titled "Toward Small-scale Characterization of Energetic Materials".

The seminar will begin at 3pm ET on October 5, 2021.

Please contact Rachel Wise for connection information.

Abstract: As money, time, and resources shrink, it is imperative we develop smarter ways to assess the performance and safety of new energetic materials. Development time from lab to production is on the order of decades. Our lab is focused on developing ways to screen new explosives molecules and formulations at the gram-scale or smaller.

Bio: Dr. Jimmie Carol Oxley is Professor of Chemistry at the University of Rhode Island (URI), the former co-Director of the Department of Homeland Security (DHS) Center of Excellence (CoE) in Explosive Detection, Mitigation, and Response, and co-Director of the Forensic Science Partnership of URI. Her Ph.D. in chemistry is from the University of British Columbia (Chemistry), and her first faculty position was at New Mexico Institute of Mining & Technology (NMT). In 1995 she and her research group moved to URI, where her lab continues to study energetic materials. Dr. Oxley has organized numerous symposia and short courses for government and industrial laboratories on topics ranging from hazards analysis to bomb threats. She is the past chair of the Gordon Research Conference (GRC) on Energetic Materials; co-founder of Life Cycles of Energetic Materials and the GRC on Illicit Substance Detection. Dr. Oxley has served on seven NRC panels/committees, a 2-year term on the NIST Organization of Scientific Area Committees on Fire Debris and Explosives, and a 3-year provisional term on the DoD Strategic Environmental R&D Program.