Maximising plasma turbulence in the hot spot of inertial fusion targets

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

The student will investigate, using relativistic fluid theory and Vlasov-Maxwell simulations, the local heating of a dense plasma by two crossing electron beams generated during multi-PW laser-plasma interactions with a pre-compressed, inertial fusion target. Heating occurs as an instability of the electron beams that drives Langmuir waves, which couple non-linearly into damped ion-acoustic waves and into the background electrons. Initial simulations show a factor-of-2.8 increase in electron kinetic energy with a coupling efficiency of 18%. By considering the collisionless energy deposition of these electron beams, we are able to demonstrate, via sophisticated radiation-hydrodynamic simulations, that this results in significantly increased energy yield from low convergence ratio implosions of deuterium-tritium filled wetted foam capsules, as recently demonstrated on the National Ignition Facility. This approach promises to augment the heating of the central hot spot in these targets, and is attractive as a complementary approach that of fast ignition inertial fusion.

The student will:
Simulate (Vlasov or possibly particle-in-cell) parameter scan of the energy cascade. The question is how dependent are we upon the electron energy, thermal spread, divergence, beam-to-background density ratio.
Simulate the energy cascade process in an inhomogeneous plasma.
Simulate energy cascade using finite beams.
Help design experiments verifying the energy cascade process.
The student will also use machine learning to study the optimisation of the energy deposition process.

This projects falls under the EPSRC plasma and laser theme.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R513295/1 01/10/2018 30/09/2023
2285085 Studentship EP/R513295/1 01/10/2019 30/03/2023 Robert William Paddock