Nuclear fusion has the potential to provide a sustainable, environmentally friendly, reliable energy source. One of the main obstacles to commercial fusion energy is the availability of sufficiently resilient materials. Components in the first wall of a fusion reactor will be exposed to extreme temperatures, intense irradiation and ion bombardment. Tungsten and tungsten alloys are very promising candidate materials for these components. With colleagues from Oxford Materials and the Culham Centre for Fusion Energy we study how the conditions in a fusion reactor would change mechanical, physical and transport properties of tungsten. We do this using ion irradiation, synchrotron X-ray diffraction, nano-indentation and electron microscopy experiments. These are combined with theoretical simulations from the atomic to the macroscopic scale.