There are many situations in both laboratory and astrophysical plasmas where violent eruptions can occur. Such dramatic events, with very short time-scales, cannot be explained solely in terms of linear theory. This research project will develop a theoretical understanding of the non-linear mechanisms responsible for such explosive growth. The focus will be on two types of instability that are relevant in laboratory tokamak plasmas, which are confined by magnetic fields to achieve the conditions necessary for fusion. These are called the edge-localised mode (ELM) and the neoclassical tearing mode (NTM). The ELM is a particularly violent event in a tokamak plasma which leads to a massive, sudden ejection of heat and particles from the plasma surface. We have developed a non-linear theory to explain this phenomenon, and in the process have identified a possible link between ELMs in tokamaks and solar eruptions. Our theory predicts that filaments of plasma erupt from the surface, and these have since been observed on many of the world's major fusion tokamak experiments. A first step of this research project will be to provide a computer code to solve the non-linear equation we have derived, which is interesting in itself as it contains a fractional derivative and a finite time singularity. The code will be used to make quantitative predictions that can be compared with experimental data. We still know little about how these filaments can release so much energy (around a megajoule) in such a short time (around 100 microseconds). A major part of the proposed work will be to explore the energy release mechanism, which will require new physics studies, possibly involving reconnection of the magnetic field lines. Understanding this is particularly important for the next step, multi-billion Euro, international tokamak called ITER, which will be constructed in France. There is a major concern that these ELM events could affect the performance of ITER, and could even cause serious damage to its structure. As well as benefits to the fusion community, we also expect the results to shed light on mechanisms for astrophysical eruptions.The tokamak plasma is generally stable to the NTM unless it gets a 'kick' from another instability. An NTM can then be excited. This kick could come from the ELM described above or, more usually, from another type of rapid instability in the plasma core called the 'sawtooth'. The NTM causes magnetic field lines to break and reconnect because of filamentary currents in the plasma, to create large coherent structures called magnetic islands . The modified magnetic topology is much less effective at confining heat and particles, which is a concern for ITER. We will adapt our theory for the ELM to explore whether or not it can explain the explosive nature of the sawtooth instability also. We will then study the implications of the model for triggering an NTM. There are two important questions for the NTM:(1) How big is the 'kick' that is provided by the ELM or sawtooth (the 'seed')?(2) How big does the kick have to be to trigger an NTM (the 'threshold')?We shall address the first through our improved understanding of ELMs and sawteeth. To answer the second question we will explore how the magnetic islands interact with fine-scale phenomena (such as the particle orbits or plasma turbulence) that influence the transport of pressure and momentum in the plasma. These transport processes influence the filamentary currents that give rise to the NTM. In fact, we believe that under certain conditions they may heal small magnetic islands, providing a threshold for NTM growth. We shall explore the mechanisms which govern this by constructing a new, state-of-the-art computer code. With this code, supported by analytic solutions to simplified model equations, we shall shed new light on reconnection events in plasmas in general, and the NTM in particular.

Enormous numbers of energetic neutrons are released when helium is produced by the fusion of deuterium and tritium at high temperatures, as in our Sun. This promises to solve the World's long-term energy needs if a controlled version can be carried out on Earth. JET at Culham has been one of the leading experimental reactors for magnetically confined fusion using gaseous plasmas, and has been an important step towards designing the international thermonuclear experimental reactor, ITER. UK fusion technology is now on the fast track and will demand a new generation of materials for commercial reactor construction. The selection of materials for ITER has been based on those available some years ago, but there are trade-offs in deciding whether to use high temperature metals that are resistant to plasma erosion but liable to be damaged by radiation and also contaminate the pure plasma, or to use light elements that are toxic (beryllium) or more easily eroded and may absorb significant amounts of tritium fuel (graphite). We want to establish a materials capability for the next generation, and in particular to exploit our capability in diamond films as a route to designer carbons as plasma-facing wall materials. This proposal intends to coat carbon tiles with diamond on a large scale, in order to lower the erosion rates, dust formation, and tritium absorption, by using the unique properties of diamond, namely high temperature stability, radiation resistance, high atomic density and unsurpassed chemical stability in the presence of hydrogen plasmas. This solution enables the preferred use of low atomic number plasma-facing materials. Computational modelling of carbon structures will complement the experimental programme in optimising the chemical and physical structure of a composite functional material exposed to radiation. If successful, this approach would enable reactors to operate for longer periods before component replacements and without compromising the tritium inventory.

Enormous numbers of energetic neutrons are released when helium is produced by the fusion of deuterium and tritium at high temperatures, as in our Sun. This promises to solve the World's long-term energy needs if a controlled version can be carried out on Earth. JET at Culham has been one of the leading experimental reactors for magnetically confined fusion using gaseous plasmas, and has been an important step towards designing the international thermonuclear experimental reactor, ITER. UK fusion technology is now on the fast track and will demand a new generation of materials for commercial reactor construction. The selection of materials for ITER has been based on those available some years ago, but there are trade-offs in deciding whether to use high temperature metals that are resistant to plasma erosion but liable to be damaged by radiation and also contaminate the pure plasma, or to use light elements that are toxic (beryllium) or more easily eroded and may absorb significant amounts of tritium fuel (graphite). We want to establish a materials capability for the next generation, and in particular to exploit our capability in diamond films as a route to designer carbons as plasma-facing wall materials. This proposal intends to coat carbon tiles with diamond on a large scale, in order to lower the erosion rates, dust formation, and tritium absorption, by using the unique properties of diamond, namely high temperature stability, radiation resistance, high atomic density and unsurpassed chemical stability in the presence of hydrogen plasmas. This solution enables the preferred use of low atomic number plasma-facing materials. Computational modelling of carbon structures will complement the experimental programme in optimising the chemical and physical structure of a composite functional material exposed to radiation. If successful, this approach would enable reactors to operate for longer periods before component replacements and without compromising the tritium inventory.

The UK has recently become a net importer of energy. It is recognized that commercial fusion power development will provide an important strategic option for energy supply by mid century. Fusion is uniquely attractive because it does not rely on the conversion of fossil fuels to greenhouse gases, nor give rise to issues associated with the long term storage of nuclear waste. The physical principles underlying thermonuclear fusion in plasmas are also central to the UK's strategic defence science capabilities. The UK is a key stakeholder in the new generation of international fusion plasma research facilities. These include the magnetic confinement facility ITER, supported by six treaty partners: the EU, the USA, Russian Federation, Japan, the People's Republic of China, and the Republic of Korea. The Culham Science Center hosts the world's flagship magnetic fusion facility, JET, together with the pioneering MAST experiment. The UK's defence science needs in this field are met in part by the US National Ignition Facility (NIF, at Lawrence Livermore National Laboratory) and by the new laser facility ORION being initiated at Aldermaston. The UK Government endorses the Fast Track strategy for magnetic confinement fusion power development and is funding the new defence-related facilities.Fusion plasma research is central to the energy, environmental, and defence needs of UK PLC. In addition, contemporary fusion plasma research offers the attractions of a scientific grand challenge, combined with a new generation of advanced large scale international facilities. This proposal seeks to create a new centre of excellence in fusion plasma physics at Warwick, with strong links to the UK magnetic fusion programme at Culham. This will be a step change enhancement that builds on the successful interdisciplinary track record of the Warwick-Culham collaboration, whose work is supported both by EPSRC (primarily through Culham) and by PPARC (primarily through a rolling grant to Warwick). The project will be jointly directed by Prof Sandra Chapman (Warwick) and Prof Richard Dendy (Culham) who have an extensive record of joint scientific and managerial collaboration. To create a new group in fusion plasmas, Warwick would appoint a permanent academic in each of three fields of fusion plasma research: experimental plasma data interpretation and prediction; analytical theory; and computational plasma physics using high performance supercomputing (HPC), linked to the Warwick Centre for Scientific Computing (CSC). The initial scientific focus will be on collisionless, kinetic effects; these are a distinctive feature of fusion plasmas approaching the ignition regime. These appointments are designed to increase UK capacity in this field, and therefore must be attractive internationally as well as nationally. Warwick will therefore in addition undertake to advertise, and subsequently support, these permanent academic posts up to the level of Reader where merited by the quality of the candidate. Each academic will be assisted by two postdocs and a PhD project student. The appointment of up to six postdocs will provide a UK-based career development channel which does not at present exist: this is particularly timely given the recent surge in numbers of high quality UK PhDs in fusion plasma physics. Close engagement with the experimental programme at Culham (MAST and JET) will be developed, and it is expected that some appointees will, for example, participate actively in JET Task Forces.

Ever wondered what makes the Sun shine? What process is capable of keeping it burning for 5 billion years and will keep it burning for 5 billion more? That process is fusion - and a tour through the inflatable Sun dome will answer all your questions! The journey starts inside the darkened dome with a high speed trip into the Sun - played as an exciting graphical animation above your heads. Here, the fusing of light atoms will be visualised, with an explanation of how this process releases vast amounts of energy and keeps the Sun burning bright.Now, with the interior lit up, the fusion process is explained further. Using the dome as an impromptu theatre stage, members of the audience are invited to 'become' atoms. With guidance from the fusion scientists on hand, they will be dressed as atoms and shown how to form the states of matter (solid, liquid, gas and plasma), how atoms/nuclei combine in the fusion process, what forces are at work and what energies are required. They thereby gain a deep understanding of the fundamentals of fusion as well as more general science themes relevant to the national curriculum (charges, atoms, forces etc.).For the final part of the journey, the lights are dimmed again, and a further graphical animation above the heads of the audience shows how fusion research is striving to harness this enormous source of power to generate electricity in the future. This will be put in the context of climate change and the continued use of non sustainable reserves of energy - again linking to broader national curriculum subjects (energy, environmental science etc. ).The Sun Dome will be a pioneering and fun journey of scientific discovery - touching on several aspects of basic science and the importance of sustainable energy to the future of the world.