Inertial confinement fusion: a defence context
Almost 30 years since the last UK nuclear test it remains necessary to regularly underwrite the safety and effectiveness of the National Nuclear Deterrent. To do so has been possible to date because of the development of continually improving science and engineering tools running on ever more powerful High-Performance Computing platforms and underpinned by cutting edge experimental facilities. While some of these facilities, such as the Orion laser, are based in the UK, others are accessed by international collaboration. This is most notably with the USA via capabilities such as the National Ignition Facility (NIF), the Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) and the Los Alamos Neutron Science Centre (LANSCE) to name but a few, but also with France where a joint hydrodynamics facility is nearing completion following establishment of a Treaty in 2010. Despite the remarkable capability of the science and engineering tools, there is an increasing requirement for experiments as materials age and systems inevitably evolve further from what was specifically trialled at underground nuclear tests (UGTs). While the data from such tests will remain the best possible representation of the extreme conditions generated in a nuclear explosion, it is also essential that new capabilities are realised that will bring us closer to achieving laboratory simulations of these conditions. For High Energy Density Physics the most promising technique for generating temperatures and densities of interest is Inertial Confinement Fusion (ICF). We will therefore need ICF for Certification of the deterrent in decades to come and hence work closely with the international community to develop this science.
Perspectives on high-energy-density science and inertial confinement fusion
Dr Kimberly S Budil, Lawrence Livermore National Laboratory, USA
At the Lawrence Livermore National Laboratory, the need to ensure the continuing reliability of the US nuclear deterrent has been the driver for a remarkable set of scientific advances in theory, computation, and experiments. In particular, the need to probe the physics of fusion ignition and matter at extremes of temperature, pressure, and density has driven extensive focus on high-energy-density (HED) science and inertial confinement fusion (ICF) research.
Novel experimental platforms and a wide range of diagnostic tools are delivering data to improve our models of hydrodynamic behavior, radiation transport, and material properties and to address the known barriers to fusion ignition. These ever-growing experimental opportunities provide a rich environment for developing the skills of our next-generation workforce and building collaborations with the worldwide HED community.
This work is performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Dr Njema J Frazier, NNSA Office of Experimental Sciences, USA
From Bethe to Betti, fusion research and the exploration of ‘hot’ science has been part of US and UK lexicons since the 1940s. Since that time, the search for ways to understand, contain, and use the energy of fusion has been part of nationwide research efforts in government, industry, and academia. This talk will cover past, present, and future highlights and opportunities in the area of inertial confinement fusion for stockpile stewardship.
Direct Drive Laser Fusion, status, plans and future
Dr Mike Campbell, Director Laboratory for Laser Energetics, University of Rochester, USA
Laser direct drive (LDD), along with laser indirect (x-ray) drive (LID) and magnetic drive with pulsed power is one of the three viable approaches to achieving fusion ignition and gain in inertial confinement fusion (ICF). In this talk the present status and future plans for LDD will be presented. The program is being executed on both the OMEGA at Laboratory for Laser Energetics (LLE) and the National Ignition Facility (NIF) and Lawrence Livermore National Laboratory (LLNL). LDD research on OMEGA includes cryogenic implosions, fundamental physics including material properties, hydrodynamics, and laser-plasma interaction physics. LDD research on NIF is focused on energy coupling and laser plasma interactions physics at ignition scale plasmas. Limited implosions on NIF in the ‘Polar Drive’ configuration where the irradiation geometry is optimised for LID are also a feature of LDD research. LDD implosions on OMEGA, developed by a statistical data based model that employs machine learning, have achieved record performance and hydrodynamically scaled to NIF energies would be predicted to produce fusion yields approaching a MegaJoule. Systematic experiments enabled by the high shot rate of OMEGA and advanced diagnostics to explore three dimensional implosion performance are routinely fielded to understand degradation mechanisms that limit the fusion performance and to develop mitigation strategies. Laser-plasma interaction (LPI) physics continues to be a major focus of LLD research. Innovative diagnostics for example that measure electron distribution functions on a single shot and increased laser/facility capabilities that enable a quantitative understanding of LPI over a range of plasma conditions created at both OMEGA and NIF have advanced our understanding of LPI. The present state of research and future plans to eventually determine acceptable operating parameters and laser requirements for LDD ignition will be presented. All present major ICF facilities are based on laser science and technology developed decades ago. To increase the operating space for target designs, LLE has developed a concept for producing a broadband (bandwidth >10 THz) UV laser with a flexible pulse format. This concept and plans for demonstrating the laser and conducting experiments on both LPI suppression and laser imprint will also be discussed in the presentation.
Progress and opportunities for inertial fusion energy in France and Europe
In this talk, Professor Tikhonchuk will consider the motivation, recent results and perspectives for the ICF studies conducted in Europe in collaboration with other research laboratories worldwide. After recalling the basic principles of the inertial fusion and its major advantages and issues, he will advocate the European approach based on the direct drive scheme with the preference for the central ignition boosted by a strong shock. It was chosen about ten years ago within the framework of the HiPER project, and the collaboration is maintained thanks to the support of the EuroFusion consortium. Compared to other schemes, shock ignition offers a higher gain needed for design of a future commercial reactor and relatively simple and technological targets, but implies a more complicated physics of laser-target interaction, energy transport and ignition. Unfortunately, Europe today does not dispose a laser installation allowing integrated ICF experiments. Consequently, the Europe laboratories are addressing physical issues of shock ignition scheme related to the target design, laser plasma interaction and implosion by the code developments and conducting experiments in collaboration with US and Japanese physicists providing access to their installations Omega and Gekko XII. Some examples of the resent results will be presented. The ICF research in Europe can be further developed only if European scientists will acquire their own academic laser research facility specifically dedicated to the controlled fusion energy. It should not be limited to the ignition issues but aim beyond ignition to the physical, technical, technological and operational problems related to the future fusion power plant. Such a programme may be realised only if the ICF community demonstrate to the political deciders that there is a critical mass of scientists and a significant amount of scientific and technical knowledge guaranteeing the success. Professor Tikhonchuk will show that indeed, there are strong arguments for that. Compared to the magnetic confinement, inertial confinement offers more compact and less expensive reactors, much smaller tritium inventory and a more efficient modular design. Recent results show significant progress in: i) our understanding and simulation capabilities of the laser plasma interaction and implosion physics; ii) our understanding of materials behaviour under strong mechanical, thermal and radiation stresses; and iii) commissioning at ELI Beamlines the first high energy laser facility with a high repetition rate opens opportunity for qualitatively innovative experiments. Professor Tikhonchuk believes that by consolidating these achievements and better organising European scientific community we may build a new international project for the inertial fusion energy in Europe.