Yotta - exploring routes to the ultimate intensity regime

The year 2010 marks 50 years since the invention of the laser and during this time lasers have undergone several major advances with far reaching impact on science and industrial/every-day applications. Historically each advance in laser performance (whether pulse duration, power or wavelength) was quickly followed by corresponding leaps in scientific progress. New regimes accessed with increasing intensity were non-linear optics, strong field physics and relativistic plasma science. Currently, the highest power lasers available are rated in Petawatt (10^15 W) units but on the horizon (5-10 years) systems are being designed to operate at the Exawatt (10^18 W) level with focused beam intensity exceeding 1024 Wcm-2 (Yotta = 10^24). This latest step change will unlock the door to the next predicted regime encompassing the exotic, unexplored world of non-linear QED (Quantum Electro-Dynamics) where electric fields are sufficiently large that it becomes possible, for example, to create particles (electron-hole pairs) from the vacuum. The over-arching strategic goal of this proposal is to ensure that the applicants' research grouping, within the Centre for Plasma Physics at QUB and known as PLIP (Plasma and Laser Interaction Physics), can build on its prominent international position in ultra-intense laser physics and on its current research interests and grow into a world leader in this emerging field. Interaction of high power lasers with matter generates a wide range of effects ranging from the generation of beams of multi-MeV particles to coherent beams of kilovolt photons. Increasing access to ultra-intense lasers allows the study of laser-plasma interactions in the relativistic regime and this opens up exciting opportunities to study and understand many non-linear processes. The general topic area has the potential to provide new approaches to many related areas including tumour therapy, space science and warm dense matter. The PLIP group covers the major research areas in the field and combines theory and experiment. Current topics include proton acceleration, harmonics from relativistic plasmas, warm dense matter (WDM), X-ray lasers (XRL) and plasma simulation.The group has recently established an internationally competitive laser facility. The TARANIS (Terawatt Apparatus for Relativistic and Non-linear Interdisciplinary Science) dual beam laser delivers 30J pulses in 1 nsec or 20J pulses in 1 psec synchronously from either beamline. Focussed intensities > 10^19 Wcm-2 enable a range of pump-probe type experiments to investigate phenomena on ultrafast timescales. Home-based work is used as a platform to access larger lasers, including FEL and XFEL systems, at national and international facilities and this approach has led to over 40 publications in Nature/Science/PRL in the last five years. There is scope to develop TARANIS to provide even higher intensity and during the platform grant period we will explore options to extend the specification to include a synchronised beamline delivering several Joule pulses with sub 10-fsec duration. Internationally, there are several very large projects (eg ELI, which promises Exawatt power levels) under development which offer access to even higher focussed intensities, approaching the regime (>10^24 Wcm-2) where non-linear QED effects are expected to become observable. Our main strategic aim is to use the flexibility of Platform Grant funding to explore some of the theoretical physics, practical problems and characterisation problems associated with this new era of scientific opportunity. A platform grant will provide a stable base within the PLIP group and the opportunity to plan ahead and engage in more speculative experiments which might otherwise not be funded. It is envisaged that we develop and consolidate a major team which will be seen as a strategic investment for UK science in the non-linear QED activity looming on the horizon.

The platform grant (PG) will provide a valuable resource for the development and training of young researchers (YRs) in the field of high intensity laser-plasma interaction physics. In addition to the specialist skills and knowledge pertaining to lasers and plasmas, students and staff working on the programme will gain experience in problem solving, team-working, high level IT skills, data analysis, project planning, communication etc - all desirable and transferable to diverse career pathways. Past PhD and PDRA personnel from our group have contributed their expertise in a range of areas including industry, academia, government laboratories, teaching and finance. Immediate benefit will fall to the 3 named YRs who are currently on short-term contracts and showing great promise. They will have opportunities to gain more experience both in-house through work on Taranis and through access to national and international facilities. YRs funded on other grants, able to make useful contributions to our planned work, will be able to access bridging funds to further develop their career paths with us before moving on. We will also recruit excellent, new blood PDRA personnel to broaden the experiences of our team. During the 48 month grant period exceptional students will complete their PhDs and we can keep them as YRs if RM or other funding is not immediately available. All post-docs will be mentored carefully - indeed they will participate in the same appraisal schemes used at QUB for members of staff and designed, in particular, for career and professional development of junior staff. As our post-docs reach an appropriate stage in their development we will actively encourage them to apply for Career Acceleration Fellowships. The main focus of our planned work on the PG will be related to development of understanding of non-linear quantum electro-dynamic effects (NL-QED) but this must be accomplished in parallel with progressing current and planned activities which also relate to high intensity laser interactions. Taken together, our research output will be useful to others working in related areas and who (like us) will benefit from new basic knowledge disseminated but there are implications with longer timescales (perhaps 10-20 years) for impact on wider communities. For example, contributions to demonstrating suitability of laser-driven ion beams to tumour therapy will attract increasing interest from the medical community. Likewise, contributions to the physics associated with the fast ignitor approach to laser fusion has the possibility of leading to the eventual construction of power plants to help solve the energy crisis. Although our research is specific to laser-plasma physics, it has a common theme with many other branches of physics, chemistry, biology etc in that it relies on diagnostics incorporating camera-based detectors which require continual development and improvement. To this end we have worked with local scientific camera manufacturer Andor Technology in test and development work on customised cameras. We are currently in discussions regarding some novel designs which may help our research ability and boost their sales lines; we will explore these options further during the period of the PG. An indirect impact which we wish to achieve relates to the UK-wide problem of attracting young people into STEM subjects. We are aware that high profile local media releases (eg firsts achieved by QUB researchers) and ability to show off world leading facilities like the Taranis laser at Open Days and School Tours attracts local interest. We plan to develop facilities for preparing and showing research-related video clips in the Taranis Control Room area for such tours and visits in an attempt to interest more young people in Northern Ireland in Science/Physics. There is scope to do this in collaboration with staff (including Physics graduate contacts) in the Belfast W5 - Interactive Discovery Centre.