Coherent and incoherent attosecond x-ray sources based on laser-plasma interactions

PhDs are offered in an exciting and challenging research area, with a vibrant group of experimentalists and theoreticians developing and applying ultra-compact accelerators and x-ray sources based on laser-plasma interactions. Students will have access to dedicated Strathclyde (ALPHA-X http://phys.strath.ac.uk/alpha-x/, SCAPA http://www.scapa.ac.uk/) and international (RAL, GSI, ELI etc) laser facilities. Our research is collaborative and involves theoretical and experimental teams working closely together. the stundet will have opportunites to interact with international collaborators and visitors. Much of our work is cross-disciplinary e.g. X-ray holography, and radiotherapy studies based on laser-driven particle beams.

The project will focus on developing the next generation of attosecond pulsed X-ray and XUV sources using both experimental and theoretical methods. There will be an opportunity to undertake either a pure theoretical PhD, an experimental PhD using high power lasers at SCAPA, or a combination of both.

The group has made pioneering advances in laser-plasma wakefield accelerators (LWFAs) and radiation sources based on them. A diverse range of topics is available for study: laser-driven accelerators and radiation sources [1-4,8-10,13,14], high field physics and radiation reaction [6,7,12], coherence development, parametric processes [5], amplification in plasma [5,14-16], attosecond science, imaging, radiobiology using particles and radiation [11], free-electron lasers (FELs) based on plasma channels [4] etc.
LWFAs can produce relativistic electron beams with energies up to several GeV by exploiting the large electric fields produced when intense laser pulses interact with plasma [1,3]. The group has demonstrated diverse applications of LWFAs, e.g. as driving compact synchrotron sources [21], gamma ray production [1] and radiotherapy [15]. The accelerating structure of the LWFA consists of a string of micron-sized “bubbles” of evacuated regions of plasma that are created by the combination of the ponderomotive force of intense, ultra-short laser pulses and the restoring force of the ions on displaced plasma electrons. Electrons can be injected into this structure from background plasma, which results in high brightness particle beams are produced with narrow energy spreads less than 1 percent [1], low emittance less than 1 pi mm mrad [13] and ultra-short duration, <1 femtosecond to attoseconds [17]. These attractive parameters should make them suitable for driving compact FELs [5], which would drastically reduce their size (from kms to metres!). PhD students will have the opportunity of working on this revolutionary technology, which could change the way science is done by making ultra-compact radiation sources widely available.

Stimulated Raman and Compton backscattering in plasma are potential methods of amplifying laser pulses to reach exawatt powers because plasma can withstand extremely high electric fields and has unique nonlinear optical properties [5,14-16]. The Strathclyde group studies Raman chirped pulse amplification (CPA) using an ultra-short probe (seed) pulse interacting with a long 1-2 J counter-propagating chirped pump pulse in a capillary discharge plasma waveguide. These are being extended to the high efficiency Raman/Compton regime using higher energy pump pulses at RAL, where the group has demonstrated the highest power amplified probe pulses to date. Higher energy Raman-CPA studies will continue at SCAPA. Theoretical studies use both particle-in-cell simulations and reduced models to investigate the nonlinear regimes and efficiency.

To explore high field physics the group is investigating Compton scattering, where momentum is exchanged between an electron and a photon. This process is central to experiments at SCAPA, RAL 10 PW and ELI, where electron bunches will interact with intense laser pulses. By developing computationally efficient models of nonlinear Compton scattering, we are investigating how this and related fundamental processes (such as radiation reaction and the Cherenkov effect) [6,7,12] will affect properties of the electron bunch, and how this will be reflected in the radiation spectrum. PhD students will have the opportunity to work in a completely new area of fundamental physics based on high power lasers.

PhD training will be given through advanced courses via the SUPA Graduate School, and tailor made residential courses, involving collaborators, for in-depth research and transferable skills training. The group has an excellent reputation in placing PhD graduates in industry, large facilities and academia. Several joint ELI-Strathclyde studentships are available on topics relevant to ELI, the Extreme Light Infrastructure, which consists of three unique EU facilities applying high power lasers. Strathclyde is a Member of the Cockcroft Institute, which provides links to the accelerator community.