Fusion is the energy-releasing process that powers the sun and other stars. If it can be harnessed economically on earth it would be an essentially limitless source of safe, environmentally responsible energy. Fusion energy is therefore strongly mission-orientated. The most promising method uses strong magnetic fields in a tokamak configuration to allow a high temperature deuterium-tritium plasma to be generated while minimising contact with the surrounding material surfaces.The UK contributes to fusion research in two ways: (i) through the UK's own programme focused on the spherical tokamak experiment MAST, and (ii) by contributing to the Joint European Torus (JET) programme. The MAST and JET facilities are situated at Culham Science Centre. International co-operation is strong with the focus on the International Tokamak Experimental Reactor (ITER), which will be the first fusion device to achieve energy gain and sustained burn.Experimental programmes on the MAST and JET tokamaks are performed to help resolve and refine understanding of key physics issues for ITER. In addition, experimental programmes on MAST focus on testing the potential of the spherical tokamak as a more compact option for future fusion devices. A strong theory and modelling group supports the experimental programmes and contributes to the research and development of fusion materials and to studies of conceptual fusion power stations. Expansion of the research and development of ITER specialist (i.e. diagnostic and heating) systems, focuses on securing major roles for the UK in the provision of two or three of these large complex projects.The results of the research are presented in reports and publications, and at conferences, expert groups and specialist committees. Collaborations with researchers in other areas of science and technologies are pursued strongly, where the research overlaps with fusion R&D.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Many current challenges in Non-Destructive Evaluation (NDE) stem from the increased use of advanced materials and manufacturing processes that push the limits of materials' performance. NDE techniques are required that can cope with extreme environments (high temperature / radioactive environments), restricted access (inside engines or though access ports), and complex geometries. To address these challenges, this project will develop a new capability for real-time, remote ultrasonic imaging that can be used for NDE. This engineering challenge will be achieved by introducing a conceptual change to phased array ultrasonics, beyond the limits of geometrical, ultrasonic frequency and mode array characteristics, by adapting the array to the demands of the inspected structure, on-the-fly, and thus transforming the field. The long-term vision behind this project goes beyond inspection, to develop a method for monitoring and control of in-process parameters, in places of extreme environments such as fusion reactors or turbine engines. The industrial importance of the project is demonstrated by the significant cash and in-kind contributions of the project partners.

This research project will apply aperture synthesis, a diagnostic technique used routinely in radio astronomy, to make the first time-resolved measurements of the current density in the tokamak plasma edge. This measurement is crucial for understanding violent eruptions known as ELMs which could be extremely damaging for ITER, the next generation fusion device. At EUR10Bn, ITER is one of the largest international science projects on Earth.Fusion involves making two positively-charged nuclei collide to produce a heavier nucleus, releasing energy in the process. This can only occur at temperatures of about 100 million degrees. The fundamental challenge to performing fusion is to confine the hot ionised gas (plasma) sufficiently well. The principle behind the leading candidate design for a fusion power plant (called a tokamak) is to use the fact that the charged particles of the plasma state respond to electromagnetic fields, which can be used to confine them away from the material walls of the device. If sufficient heating power is injected into a tokamak plasma, then it enters a high-confinement mode. In this mode, the thermal energy of the plasma increases by about a factor of two due to the creation of a highly insulating layer near the plasma edge, which is typically only a few centimetres thick, compared to the body of the plasma which can be a metre or so across. The pressure gradient in this edge layer is extremely high, so there is a vulnerability to instabilities. The plasma experiences a repetitive series of violent plasma eruptions called Edge Localised Modes, or ELMs, which expel large amounts of energy typically within about a hundred millionths of a second. These are an interesting scientific phenomenon on today's tokamaks but on ITER, where the ejected power in an ELM is expected to be an order of magnitude larger, they could cause serious damage if not controlled. There are ideas for how to control ELMs that work on existing tokamaks, but to extrapolate them reliably to ITER requires a more detailed understanding of the physics. In order to test and constrain theoretical models for ELMs, we need to be able to measure the current density and pressure gradient in the thin edge layer. While a number of tokamaks have a good measurement of the pressure gradient, the current density is much more challenging, and the role of the current density in ELMs remains unconfirmed experimentally.This project will develop a novel diagnostic technique to measure the edge current density on the MAST tokamak routinely (in the sense that in principle the process could be automated). Our diagnostic technique will also have good time resolution, being able to make several measurements of the edge current density through an ELM and address the intriguing question of how (or whether) the current density is flushed out of the plasma edge region within the ELM time-scale (ie about 100 microseconds).The physical basis for this diagnostic technique is the directional emission of electron Bernstein wave (EBW) radiation, which is an example of electron cyclotron emission (ECE). Bernstein waves are electrostatic plasma waves generated in the plasma core at frequencies typically around tens of gigahertz. Most of these outgoing waves are reflected back into the core from a cut-off layer, but waves travelling at a particular angle with respect to the equilibrium magnetic field undergo a mode conversion to an electromagnetic wave that enables them to travel to the plasma edge and to be observed. The EBW emission profile allows us to measure both the direction of the magnetic field, and the rate at which it is changing. Since we know the absolute value of the toroidal magnetic field (it varies inversely proportionally with the distance from the centre of the device), we can use the rate of change of direction of the field to calculate the current density.

Summary For a lot of academic and industrial research into nuclear energy, using NNUF and other facilities, it is important that neutron-irradiated material of known provenance is available. Getting samples irradiated in reactors is both time-consuming and expensive, and as much use as possible should be made of existing material. There is a wide range of surveillance and other samples in the UK, owned by organisations like the Nuclear Decommissioning Authority (NDA), EDF Energy and Rolls-Royce. Establishing either a central or distributed archive of a selection of this material that can be accessed by researchers has been identified as a priority by the UK Government's Nuclear Innovation and Research Advisory Board (NIRAB). The archive is the second item in the table of favoured investments in EPSRC's NNUF Phase 2 call. While the Irradiated Materials Archive Group (IMAG), comprising universities, National Nuclear Laboratory (NNL), UK Atomic Energy Authority (UKAEA), NDA and other stakeholders, has developed this concept, further work is required before the key stakeholders are in a position to decide if and how to proceed. Options could range from leaving the material where it presently is and having systems that enable individuals to ascertain the material and pedigree available, and request samples for their research, to bringing samples from locations in the UK to dedicated stores at Sellafield (higher activities) and UKAEA's Culham site (low-activity). It is, therefore, proposed that the archive is taken forward in two stages. Stage 1 is an option study and the subject of this proposal. At the end of Stage 1, key stakeholders - including EPSRC, the owners of the material and the managers of proposed stores - would decide whether to proceed and with which option. Stage 2 would require a new proposal for funding based on cost estimates established in Stage 1. However, an upper bound for the latter is indicated in this proposal. Important considerations in Stage 1 include: ascertaining what material samples are available and which are of interest to UK researchers; logistical issues including ownership and liability, transport and waste disposal; and the requirements for the archive database(s). An attractive option for the last of these may be for NDA and other owners of material to manage their own databases in a way that permits users to interrogate these and request samples. UKAEA, NNL and the University of Bristol (UoB) propose to undertake Stage 1 and produce an options appraisal for EPSRC and its NNUF Management Team, having consulted all stakeholders. This would take 19 months and require £524,000. Wide-ranging support for this proposal is confirmed by letters from Dame Sue Ion (first chair of NIRAB), the CEO of the Henry Royce Institute for Advanced Materials and AWE. The NDA has been consulted in the drafting of this proposal and expressed its willingness to collaborate in the project, as has Rolls-Royce in its letter of support. The US has had a national archive for some years and learning from its experience would be part of this project; a letter confirming the value of the archive is from the Director of Nuclear Science User Facilities at Idaho National Laboratory.