Fatigue is the most pervasive failure mode that affects nearly all industrial sectors - including energy industries involving power plants, anemo-electric and tidal stream generators; transport vehicles and aircraft; national infrastructure such railway and bridges; military equipment from a blade in an engine to a whole ship; medical devices and human body implants. The economic cost of fracture has been enormous, approaching 4% of GDP, whereas 50-90% of all these mechanical failures are due to fatigue. Most fatigue failures are unexpected, and can lead to catastrophic consequences. In safety-critical sectors such as the aero-space and nuclear industries, there are ever increasing demands for better understanding of fatigue with respect to the microstructure of metallic components and the demanding environments that they are placed in. The ultra-small, ultra fast fatigue testing techniques I have created are able to make a breakthrough by addressing the classic needle in haystack problem in fatigue crack initiation (FCI) and short crack growth (SCG). Fatigue at these early stages is localized within a few hundred micro-meters. However, they account for more than 50% life in low cycle fatigue (LCF) and approximately 90% in the high cycle fatigue (HCF) regime, and contribute to the largest portion of scatter. My micro- and meso- cantilever techniques are capable of isolating FCI and SCG in selected microstructure features, allowing for the systematic exploration of slip evolution, slip band decohesion and short crack propagation in the context of an exquisitely well characterised volume of material. The ultra-fast testing rate up to 20 kHz means robust exploration can be achieved to 10^9 cycles and beyond, in hours in contrast to months or years demanded by the conventional method. This proposal, through further development of state-of-the-art extremely small and fast fatigue testing techniques, looks to radically change the technical scope of fatigue analysis by allowing environmental effects to be systematically explored at the levels of FCI and SCG and across the HCF and LCF regimes. In-situ ultrasonic fatigue testing rig will be installed in an advanced scanning electron microscope, enabling in-situ observation of the progression of HCF FCI and SCG at the resolution of ~ 1 nm. I will apply these cutting edge techniques to underpinning major fatigue issues in Ti and Ni alloys of technologically importance to the aero-engine industry and proton accelerators, specifically: (i) To achieve a breakthrough in mechanistic understanding of HCF FCI and SCG in titanium alloys with respect to the environments and deliver essential HCF FCI and SCG properties; (ii) To make groundbreaking study of fatigue in Alpha Case and dwelling fatigue in titanium alloys, which are major issues in aero-engine industry; (iii) To determine the effect of the heavy irradiation on HCF performance of Ti-alloys that will be used in the next generation proton accelerators; (iv) To achieve comprehensively understanding of the environmental effect on fatigue in single-crystal nickel superalloys that have the heterogeneous distribution of gamma' phase and element segregation; (v) To determine the HCF and LCF performance of the multi-functional coatings on the surface of a nickel turbo blade in the context of atmosphere, temperature and pre-corrosion treatment. A Ultrasonic Fatigue Testing Centre will be established to satisfy the frequent HCF assessment requests from the industry. The new functions developed on the ultrasonic fatigue testing rig in this project will be transferred to the national lab at Culham to update the bespoke rig in a 'hot cell', for study of active materials in support of fission and fusion innovation.

THz frequency (300GHz to 1THz) radiation sources are used in a number of diverse applications such as radars, the study of the fundamental properties of materials, security imaging, magnetic resonance spectroscopy, plasma diagnostics, medical imaging and chemical sensing. The power that can be generated from 'bench top' free electron radiation sources in the hundreds of GHz to THz frequency range has been limited by the fact that as the frequency is increased, the size of the interaction region has to be reduced in order to prevent the maser becoming overmoded which results in a loss of the temporal or spatial coherence of the output radiation. As the frequency increases it becomes increasingly difficult (if not impossible) using conventional thermionic cathodes to focus and form high current density, high quality electron beams through the small size interaction region of the THz maser. A pseudospark plasma cathode can overcome current density limitations imposed by thermionic emission as well as being able to generate a sheet electron beam without the need to use an external magnetic field. A psuedospark-sourced sheet electron beam will be used to power a planar Extended Interaction Klystron Amplifier (EIKA) which is extended in one direction as compared to conventional EIKAs based on a cylindrical electron beam produced by a thermionic cathode. A 12mW, 365GHz signal generated by a solid state source will amplified to 100W by the Pseudospark Sheet beam planar Extended Interaction Klystron Amplifier (PS-EIKA). As no guide magnetic field is required the PS-EIKA will be compact, reliable, robust and can generate 100ns duration pulses at high (kHz) pulse repetition frequencies. In addition a pseudospark source sheet electron beam will be used to drive a planar Extended Interaction Oscillator (EIKO) to generate 10W of output power at 1THz. The proposed research will be conducted jointly by two leading research groups in microwave device engineering with complementary expertise, in Univ. of Strathclyde and QMUL. Knowledge of pseudospark Extended Interaction Klystron amplifier (PS-EIKA) and oscillator design and construction will be transferred to our Project Partner. A community network of THz amplifier users in magnetic resonance spectroscopy, plasma diagnostics and mm-wave radar applications will be built up to the benefit of future co-created research collaborations. These include the use of the PS-EIKA in Electron Paramagnetic Resonance (EPR) and to improve the sensitivity by many orders of magnitude of Nuclear Magnetic Resonance (NMR) through DNP techniques. The EPR and DNP enhanced NMR (including the possibility of pulsed DNP-NMR and the use of phase and amplitude modulation) experiments will strongly enhance the UK's position as a world leader in a wide range of academic research areas in physics, chemistry, biology, engineering and medicine. These sources are also of national and international importance in the areas of magnetically confined fusion for plasma diagnostics and mm-wave radar systems. New high power sub-millimetre wave amplifiers and terahertz oscillators will be constructed for radically improved sensitivities in NMR/DNP and EPR instruments in high magnetic fields, enhanced plasma diagnostics and THz imaging. Network activities as part of the proposal will bring together leading groups/industries in the magnetic resonance spectroscopy, microwave plasma diagnostics community and the high power amplifier and microwave/mm-wave source community. Increased capability in these areas as well as enhanced capability to measure fast and slow moving objects using sub-millimetre wave radars will be exploited via our Project Partner. All network members have an outstanding track record in relevant technology and methodology development and all have strong links with National and International applications programs with multiple collaborators across RF and Microwave science and technology application areas.

Fusion is the process that powers the sun. If we can harness fusion power on Earth, it would provide effectively limitless, carbon-free, safe energy. There are two approaches. In inertial fusion energy (IFE), high power lasers (or other 'drivers') compress a pellet of frozen deuterium-tritium fuel to very high density and temperature, confined for short times associated with the fuel's inertia (nanoseconds). The other approach, presently the more advanced, is magnetic fusion energy (MFE). Here the hot, low density fuel is held in a toroidal chamber using magnetic fields for confinement times of seconds. When the fuel is heated to fusion temperatures (100,000,000K), the electrons are stripped from the nuclei, creating an ionised gas called a plasma. Plasmas are susceptible to a range of waves and instabilities that drive turbulence and degrade confinement. In MFE this determines the device size. For example, the 16Bn Euro ITER facility is large enough to give the required confinement despite the turbulence, providing a fusion yield of 10 times the applied heating power. Scheduled for completion in 2020, ITER will provide the first plasma with heating dominated by the energetic alpha particles produced by the fusion reactions, allowing the final physics questions to be answered to build a demonstration power plant, DEMO. For example, how do the alpha particles affect the plasma stability and turbulence, and how do we exhaust them from the plasma once they have cooled to avoid dilution extinguishing the fusion burn? The other fusion product is a 14MeV neutron to be captured in a blanket to extract its energy and react it with lithium to produce tritium. Understanding how materials behave under this energetic neutron irradiation, combined with exposure to hot plasma, is something we still know little about because ITER will be the first device to create these conditions. ITER will also address a range of fusion technologies, such as heating systems, tritium breeding blankets and exhaust handling: issues that integrate plasmas with materials. The flagship IFE facility is NIF in the US. It tried to achieve fusion conditions during 2012, but did not succeed. The reasons require more research, but again plasma instabilities are a likely cause. Once the issues at NIF are resolved the priorities for future laser-based systems (e.g. HiPER) can be defined on the route to inertial fusion energy. Then the materials issues discussed above for MFE apply to IFE also. IFE creates extreme states of matter with high energy density that have important applications beyond energy. One is to create conditions suitable for benchmarking the computer codes that contribute to the UK's nuclear deterrent, avoiding the need for weapons testing: important in the strategy to avoid proliferation. AWE has recently commissioned a large laser facility, Orion, primarily for this purpose. Fusion research interfaces with several fields. There are synergies with the nuclear industries where the next generation fission reactors will have high energy neutrons and so share some materials issues with fusion. Space plasmas share phenomena also found in MFE plasmas while energetic astrophysical phenomena can be simulated in the lab using high power lasers. In industry, low temperature plasmas with similar characteristics to those at the edge of a MFE plasma have applications in manufacturing, from advanced coating technologies to computer chips. The focus of our CDT is fusion, training 5 cohorts, each of 15-16 PhD students, across the range of plasma, materials, IFE and MFE, as well as related fusion technologies. This will position the UK to take advantage of new high power laser and MFE facilities, advancing fusion energy. IFE, along with lab astrophysics, will develop skills relevant to the UK's national security strategy. Our training programme will seek to benefit other students in related fields, such as technological plasmas and nuclear materials.

Ceramic-matrix composites (CMCs) have the qualities of being strong, tough, lightweight and stable at high temperatures; they are considered as a serious material candidate to replace superalloys for many applications, such as in the core of gas-turbine engines with the aim of increasing operating temperatures, reduce the need for air cooling, and thus enable superior fuel efficiency to reduce harmful emissions. Over the last ~20 years, CMCs have been used in the augmentor sections of large military engines. Followed major investment from numerous companies and R&D organisations, mainly in the US, EU and Japan, new carbide technologies have been developed to aid the transition of CMCs to commercial gas-turbine engines, not to mention future applications in hypersonics. Despite the fast-growing CMC market, there is not yet an established CMC materials supply chain in the UK. Internationally, the design and processing of the CMCs also are still a challenge due to their complex microstructure (fibre, matrix and porosity). Therefore, there is an important opportunity for the UK to participate and ultimately lead, or at least share in, the global effort in CMC development. These are definitely the prime structural materials of the immediate future. As a structural material, the mechanical performance of CMCs at elevated temperatures has been a critical factor for consideration in materials validation and adoption. To achieve an optimised design for a particular application, a sound understanding of the evolution of damage and failure mechanisms in CMCs, and how they relate to the intrinsic processing-microstructure-property relationships under extreme conditions, is undoubtedly the key. This sets the imperative and the horizon of the proposed work programme. In this project, a unique and step-changing, real-time, 3D imaging method will be used to capture the deformation and fracture of CMCs at ultrahigh temperatures (~1000C to 1800C) representative of potential service conditions. By combining with techniques such as diffraction, micro-scale mechanical and multi-scale modelling methodologies, the underlying mechanics controlling the damage evolution in these materials at unprecedented temperatures can be understood and related to processing for improved material design. The materials studied in this project will be processed or designed in the UK with the aim of enhancing UK-based industrial expertise in CMCs, but also access to international materials that are available. The primary materials of interest are two CMC types that are of high demand in aerospace, automotive and energy applications: continuous fibre reinforced SiC-SiC and alumina-alumina CMCs with the former being most important as a game-changer for advanced, lightweight, super-efficient propulsion units. However, compared to conventional superalloys, these materials are new; what has been lacking from a scientific perspective has been their characterisation in terms of two key aspects: (i) the local properties of the individual constituents, fibre/matrix interfacial strength and residual stresses in the fibre/matrix as a function of process parameters, and (ii) the real time imaging of their damage accumulation leading to crack initiation, in relation to their 3D microstructures, at realistic service conditions, i.e., ultrahigh temperatures, to simulate the working environment of these CMCs. This project will target at both material types with the support from materials processing partners (e.g., Birmingham Univ.) and end-users (e.g., Rolls-Royce plc, Cross-Manufacturing and Westinghouse). Last but not the least, this project will work closely with modelling experts (e.g., Oxford Univ., Delft Univ. of Technology, and Institute Eduardo Torroja of Construction Sciences) by providing experimental results over multiple length-scales to develop a framework of a microstructure-based mechanistic model for the evaluation of the damage tolerance of CMCs.

The science and engineering of materials have been fundamental to the success of nuclear power to date. They are also the key to the successful deployment and operation of a new generation of nuclear reactor systems. The next-generation nuclear reactors (Gen IV) operating at temperatures of 550C and above have been previously studied to some extent and in many cases experimental or prototype nuclear systems have been operated. For example, the UK was the world-leading nation to operate the Dounreay experimental sodium-cooled fast nuclear reactor (SFR) for ~19 years and a prototype fast reactor for ~20 years. However, even for those SFRs with in total of 400 reactor-years international operating experience, their commercial deployment is still held up. A formidable challenge for the design, licensing and construction of next-generation Gen IV SFRs or the other high-temperature nuclear reactors is the requirement to have a design life of 60 years or more. The key degradation mechanisms for the high-temperature nuclear reactors is the creep-fatigue of steel components. When structural materials are used at high temperature, thermal ageing and inelastic deformation lead to changes in their microstructures. The creep and creep-fatigue performance of structural materials are limited by the degradation of microstructures. The underlying need is to develop improved understanding and predictive models of the evolution of the key microstructural features which control long-term creep performance and creep-fatigue interaction. This Fellowship will use an integrated experimental and modelling approach covering different length and time scales to understand and predict the long-term microstructural degradation and creep-fatigue deformation and damage process. I will then use the new scientific information to make significant technological breakthroughs in predicting long-term creep-fatigue life that include microstructural degradation process. I will thereby realise a radical step beyond the current phenomenological or a functional form of constitutive models which received very limited success when extrapolated to long-term operational conditions. This research will put me and the UK at the forefront of nuclear fission research. This Fellowship will enable the 60 years creep-fatigue life of the next-generation high-temperature nuclear systems by developing a materials science underpinned and engineering based design methodology and implement it into future versions of high-temperature nuclear reactor design codes. In consequence, Gen IV reactor technologies will become commercially viable and Gen IV SFRs will be built globally to provide an excellent solution for recycling today's nuclear waste. This fellowship aims to influence the international organisations responsible for the next-generation nuclear design codes and gaining an early foothold in the international nuclear R&D via this research will give the best chance to secure Intellectual Property and return long term economic gains to our UK.