I am a PhD student in the superconductivity group at Durham University, supervised by Prof. Damian Hampshire.The commercialisation of fusion energy as a source of energy production poses many challenges, with one of the biggest ones being the cost that comes with it. Observed values of the critical current densities in superconductors are found to be orders of magnitude smaller than values predicted by theoretical models. Through an understanding of the mechanisms that lead to this, finding improvements in the critical current density in superconductors by even a factor of two would lead to substantial reductions in costs associated with superconductors in next generation tokamaks. As part of my project, I will be using Time-Dependent Ginzburg-Landau (TDGL) Theory in conjunction with the power of computation to simulate low and high temperature polycrystalline superconductors in 3D to determine the mechanisms that govern the critical current density of high-field superconductors in fusion tokamaks.