29 May 2014
Professor Donnelly’s group works on laser-based fusion, for which they need to deliver micron-size particles to the focus of the THOR laser. They use a second laser pulse to blast particles off a prepared silicon wafer. This scanning electron micrograph shows the damage left on the silicon wafer after the ablation pulse has cleared an area of 2-micron-diameter spheres. The hexagonal close packing pattern of dots of damage suggest that either some sort of lensing is occurring performed by the spheres or the residue which holds the spheres in place remains on the surface after ablation.