Effect of Different Charged Particle Stopping Power Models on Icg Ignition

Thermonuclear fusion holds the potential to be a source of clean abundant energy. Inertial confinement fusion (ICF) is one means of achieving significant, controlled fusion burn. In ICF, a small amount of frozen deuterium/tritium fuel is compressed to many times solid density and temperatures greater than 10,000 eV. In these targets, fusion burn initiates in a low density hot spot and then propagates into the cold fuel. The burn wave propagates by way of fusion products being born in the hot spot then slowing down in the fuel and heating it in the process.

In this thesis, we study the stopping power models that describe charged particle slowing. In particular, we analyze the assumptions made in theses models and how those assumptions limit the use of these models in ICF ignition conditions. We implement twelve of these models in a stopping power library called "Deeks" that includes both the stopping power calculations and the consistency constraints of the models. We then integrate Deeks into a 1D multi-physics radiation-hydrodynamics code called "Bucky" to perform integrated target implosions with the stopping power calculations of the fusion product transport performed by Deeks.

We use a shock ignition target as a test bed to compare the effect of different stopping power models on target performance. As some fraction of target conditions are expected to be outside many models consistency constraints, we use a three tiered model for calculating stopping powers that gradually degrades to simpler models as target conditions get further away from conditions consistent with the stopping power model's derivation. We find the conditions of the cold fuel to be substantially inconsistent with the ubiquitous assumption of weak plasma coupling and the application of weakly coupled stopping power models to ICF ignition to be very limited.

Finally, facilitate the use of shock ignition targets as a fusion burn test-bed, we have developed a program for automatically tuning a shock ignition laser pulse for a given target.