Newsletters (Spring 2020, Page 13
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Spring 2020, Number 16 Department of Physics Newsletter COVID EARTH Oxford Physics researchers and alumni join the race to help understand more about the SARS-CoV-2 virus THE FUTURE OF INERTIAL FUSION A STEP CLOSER INNOVATION NOBEL PHYSICS TO BUILDING – THE NEXT LAUREATE VISITS THE FIRST MUON GENERATION OXFORD COLLIDER www.physics.ox.ac.uk PROUD WINNERS OF: SCIENCE NEWS SCIENCE NEWS www.physics.ox.ac.uk/research www.physics.ox.ac.uk/research be shown that to create those 2 x 1016 currently undertaking will soon be that propagates through the fuel. The neutrons, a process known as ‘alpha able to address this question. burn-wave converts the kinetic energy burn’ must be taking place – that is of the imploding fuel capsule into the THE FUTURE OF to say the alpha particles produced by fuel’s thermal energy by the time the fusion are themselves starting to heat TO RELEASE ENERGY, FUSION wave reaches stagnation at the capsule COMBINES TWO NUCLEI; FISSION up surrounding colder deuterium and SPLITS A NUCLEUS centre. Commercialising inertial fusion tritium nuclei, causing them in turn to energy requires repeated injection of INERTIAL FUSION fuse. It is as though the target is starting All approaches to nuclear fusion must fusion pellets and the deployment of Prof Peter Norreys This March, at a Hooke Discussion Meeting at The Royal Society, Peter Norreys, Professor to ‘fizz’, or ‘glow’, but not yet fully ignite. satisfy a criterion, memorised by high-repetition (5–10 repetitions per of Inertial Fusion Science at Oxford University’s Department of Physics, brought together INDUSTRIAL fusion scientists, which states that the second) burn-wave drivers. A further reason for excitement is product of the density, temperature nearly 100 leading fusion scientists from around the globe. They met to discuss the future SPIN-OFFS the sheer neutron flux itself, and the of producing net electrical power from the nuclear reactions that take place inside igniting and confinement time of the fusion OFTEN applications that the result brings. fuel must exceed a certain threshold WELL-TIMED TECHNOLOGICAL ASPIRATION nuclear fuel at the extremes of compression, heat, and electromagnetic radiation. The goal ACCOMPANY These huge numbers of neutrons are value for the energy gain to be positive produced from a tiny compressed core of this initiative was an internationally endorsed roadmap that could assess the viability of a instead of negative. To maintain the If achievable, the realisation of IFE TECHNOLOGICAL about 100 microns in diameter, and potentially ‘transformative’ technology. fuel’s required ultra-high temperature, could be transformative for humankind Prof Gianluca Gregori the fusion reaction is over in about 100 ADVANCES, AND all fusion devices must prevent the because it allows us to envisage strategies The motivation and objectives for nucleus. This process takes place during fusion research has been impressive picoseconds. As such, the neutron flux FUSION BREAK- fusion fuel from coming into thermal for minimising the human causes of this international collaboration arose compression and stagnation before relative to its modest government- emanating from the core at the time of contact with the surrounding reactor climate change. There are no long- from an Enabling Research grant from the fuel eventually expands from the provided research budget, especially THROUGHS ARE implosion (neutrons per second per vessel. lived radioactive by-products if the EUROFusion, part of EURATOM, increasingly high pressure. While two in areas related to the assembly and unit area) is not very far off that which NO DIFFERENT reactor chamber materials are carefully awarded in January 2019 to Professor hydrogen nuclei are sufficiently close, understanding of the high-energy- exists when a supernova explodes! There To reach the fuel’s required ultra-high selected. An inertial fusion energy Norreys. The funding supports even for this short duration, the strong density conditions in the compressed are thus already a wealth of ground- density and temperatures, all fusion reactor must be compatible with the preparations for experiments on the but short-range nuclear force dominates fuel, as well as in the enabling breaking scientific discoveries, ranging devices must inject energy into the fuel. existing electricity infrastructure PETAL/LMJ facility in Bordeaux, over the tendency of ‘like charges’ to technologies required for inertial fusion from stellar astrophysics to quantum Magnetic confinement fusion uses strong Prof Justin Wark distribution and generation grid. The France, and focuses on advancing repel, inherent to the hydrogen pair’s energy applications. These technologies electrodynamics, that can be unleashed confining magnetic fields over ultra-long process is inherently safe from nuclear inertial fusion energy science and positive electric charge, that dominates include high-repetition-rate lasers, by studying physics related to the pursuit time-scales at intermediate energy meltdown, each nation can have security engineering using high-power laser when separation exceeds the nuclear heavy-ion beam drivers, pulsed-power of IFE, even before (or if) it is realised density. This research is now underway of abundant long-lasting fuel supply, and facilities across the European Union. The force’s range. magnetic-compression generators, and as an eventual goal. That is to say, we at the Culham Centre for Fusion Energy helium-exhaust emission is friendly to project’s consortium comprises fifteen high-reproducibility cryogenic-target can undertake extremely exciting with experiments at the Joint European the environment. laboratories in nine nations, including During each fusion event, a sudden and ‘assembly and qualification’. We believe fundamental research whilst at the Torus (JET), the spherical tokamak the United Kingdom. intense release of energy occurs because that the work done by hundreds of same time furthering our understanding MAST and StEP programmes at Culham Industrial spin-offs often accompany the rest mass of the fusion products (a scientists in this field has brought us The project’s of what a potential fusion power plant and the International Thermonuclear technological advances, and fusion helium nucleus and a free neutron) is closer to the point where controlled may look like. Experimental Reactor (ITER) in France. breakthroughs are no different. For COULD INERTIAL FUSION MAKE AN less than the combined masses of the fusion reactions can be attained in a consortium Research underway at the Lawrence example, investment in the laser- IMPACT IN EFFORTS TO COMBAT The latter, however, still remains a very deuterium and tritium ions. (Remember repeatable manner, although still not at comprises Livermore National Laboratory in related photonics industry will generate CLIMATE CHANGE? challenging task, with many hurdles that energy equals mass multiplied the repetition rate and cost that would be the USA (as mentioned above), and many new spin-offs and highly skilled fifteen yet to overcome. In addition, honest For many years, fusion energy has been by the square of the speed of light, ie necessary for a reactor. For example, the the Laser MegaJoule facility in France jobs. The Institute of Physics (IoP) 2 assessments are needed to ascertain described as the holy grail of the world’s E=mc .) If these fusion reactions occur international facility closest to achieving laboratories in (figure 1) uses inertial confinement estimates that the photonics industry whether any potential technologies energy problems – a limitless and clean at a sufficient rate, then more energy is ‘breakeven’ is the National Ignition over ultra-short time-scales at high in the UK contributes £13B annually nine nations, could impact on the timescales relevant energy source that would address the generated than is expended to drive the Facility (NIF) – a giant laser at Lawrence energy density. to the economy. The IoP has recently to the current pressing climate issues, ever-increasing demands, free from compression in the first place. This heat, Livermore Laboratory in California, including pointed out that the industry’s status or whether they might instead form In the inertial fusion approach, the carbon emissions. This is an aspiration if captured in a surrounding blanket, that holds the record for the largest the United as an enabling technology for multiple part of a second wave of clean energy energy is injected by suddenly impacting that has stimulated the minds of great as in a conventional power plant, can number of neutrons produced in a single uses across numerous sectors means 16 Kingdom technologies. The research we are a fuel capsule with a fusion burn-wave scientists, but the path towards an drive a steam turbine that generates laser-driven fusion event (2 x 10 ). To that it still lacks a singular champion economically viable fusion power plant electric power. put this in the context of IFE, this vast of the importance of photonics. The is an arduous one. number of neutrons has an energy of Figure 1. The 10 m IoP’s recent report (https://beta.iop. However, the reality is that controlled only a few percent of the close to 2MJ diameter target org/health-photonics) by the photonics Inertial fusion energy (IFE) requires the thermonuclear fusion has not yet been laser pulse that created the reaction that chamber installed community has appeared online. It thousand-fold compression of matter to proven. Indeed, the idea of laser-driven produced them. Furthermore, the NIF in the laser bay of provides a powerful insight into the ultra-high densities and temperatures fusion was first put forward by John can only fire shots to achieve such fusion the Laser MegaJoule forthcoming photonics revolution. In to mimic the compressional effect Nuckolls in 1972, close to half a century reactions about twice a day – for a power facility, Bordeaux, the longer term, the UK government of gravity in the sun, nature’s very ago, and despite enormous progress plant this would need to happen ten France. The target is committed to significantly increased effective nuclear fusion reactor.