Relativistic plasma optics and collective particle dynamics in dense plasma

Exploiting relativistic phenomena in intense laser-plasma interactions has led to significant breakthroughs in applications such as charged particle acceleration and the generation of ultra-short bursts of high energy radiation. Even the most fundamental properties of a relativistic plasma such as its index of refraction are profoundly affected by nonlinearities in electron motion. The interplay between intense laser light and the plasma not only modifies the light propagation, but also defines the properties of high energy particles and radiation produced.
One such relativistic phenomena - induced transparency - can produce laser self-focusing, the transmission of shorter pulses with a fast rising edge (through thin foils) and is predicted to change the laser polarisation. If developed and controlled, these effects could be applied for the active manipulation of intense laser pulses for applications. We have recently shown that a self-generated relativistic plasma aperture is produced in a thin foil undergoing transparency, which induces diffraction of the transmitted laser light. The resulting near-field diffraction pattern transversely displaces plasma electrons and can be controlled to produce helical plasma structures and other collective electron motion. This concept can be used to manipulate the charge separation-induced electrostatic fields responsible for ion acceleration.

The project builds on this programme of work and will provide new understanding of the properties of the laser radiation transmitted during RSIT and thus underpin the development of relativistic plasma photonics aimed at achieving tuneable temporal, spatial and polarisation control of laser pulses at ultrahigh intensity and contrast. This will include experimental investigations using the new 350TW state-of-the-art laser at the Scottish Centre for the Application of Plasma Accelerators (SCAPA) in the Physics department and external larger scale high power laser facilities at the Central Laser Facility in Oxfordshire. Opportunities also exist for the student to contribute to future experiments at the new Extreme Light Infrastructure (ELI) facilities under development. The project also involves numerical simulation of intense laser-plasma interaction phenomena to help guide the interpretation of experiment results.

The objectives of the project are to:
1. Characterise the laser pulse temporal shaping and gating
2. Determine the influence of the laser focus spatial-intensity distribution
3. Investigate Relativistic transparency-induced laser polarisation distributions