Laser-driven fusion: the Polar Direct Drive Shock Ignition approach
Join Robbie Scott at the Central Laser Facility (STFC) and Nigel Woolsey in the Physics Department (York) and contribute to an international effort to achieve fusion energy gain through Inertial Confinement Fusion (ICF). This project will explore the possibility of using the National Ignition Facility (NIF) in the USA to pursue an advanced approach to ICF referred to as ‘polar direct drive shock ignition’. The project will have a computational bias but is firmly based around the interpretation of experiments. You’ll have the opportunity to use advanced radiation hydrodynamic models to study implosions, and new computational techniques to address the complex physics associated with laser-plasma interaction and the effect of overlapping many laser beams to assess the impact of multiple overlapping beams
This is an exciting time, as NIF is in the process of acquiring the optics needed for polar direct drive and you’ll have the opportunity to collaborate on NIF experiments with the Universities of Rochester (who also operate the Omega laser) and Alberta. You’ll have opportunities to travel as well as develop expertise in computational and theoretical approaches and link this to an exciting experimental programme of work.
Currently, the NIF is configured to drive ICF experiments using indirect drive. Here the NIF beams (192 of them) enter both ends of cylindrical cavity, called a hohlraum, from the north- and south-poles to create a uniform x-ray drive. This x-ray, i.e. indirect, drive implodes a millimetre scale spherical capsule containing deuterium and tritium fuel placed at the centre of the hohlraum. In direct drive, there is no hohlraum, and laser beams irradiate the capsule directly. As the NIF beams are arranged around the north- and south-poles of a sphere, new optical elements are needed to shape the laser focal spots to create a so-called polar direct drive platform. Shock ignition separates the compression of the fuel from the process raising the fuel temperature to initiate nuclear fusion burn. In this scheme a strong shock is launched late in the compression phase and the collision of shocks close to the compressed capsule centre rapidly raises the temperature to hundreds of millions of Kevin. These temperatures are needed to ensure there are enough nuclear reactions to sustain a fusion burn.