The Origins and Development of Free-Electron Lasers in the UK

This review article covers close to 45 years of free-electron laser (FEL) activity in the UK from the mid 1970s until 2022. Technical details of the projects are given together with personal insights provided by those who worked on specific projects. Both funded and unfunded projects are included to highlight the breadth of ideas generated over the years; this approach also clearly reveals the evolution in FEL activities from the early imperative to reproduce and understand first results at long wavelength towards the development of ever-higher-quality FEL output at very short wavelengths. Also included are the longer-term and broader benefits of the early projects. One aspect of this is the many years of UK experience in the design, operation and use of FEL facilities (in the UK and abroad) which reveal the wider value, financial and intellectual, of much of the work that has been undertaken and that is often not apparent. Continuous development of the UK technological base in this area has led to innovative contributions on a global scale and considerable financial return.