Speaker
Description
The performance and efficiency of the future linear accelerators is determined by the quality of the RF structures used to accelerate the particle beams. This quality is affected by the inner surface of the structures which are subject to field emission of electrons and even cause vacuum breakdowns at the desired high acceleration gradients. Better understanding of the mechanism of the forming of the field emitting spots under the electric field is needed to mitigate the breakdown process. We are addressing that issue with an atomic scale study of the surface of the accelerator structure by measuring breakdown, pre-breakdown and Fowler-Nordheim tunneling curves in the scanning electron microscope (SEM). Our in-SEM high voltage system setup measures the tunnel current in a DC mode between a sharp needle and surface under vacuum conditions. The needle and the sample is positioned using in-situ piezo stage which provides nanometer lateral resolution. To understand the structural and chemical modifications at the mono-layer of the surface in the breakdown region we use high resolution SEM and X-ray photon electron spectroscopy. We present the latest results and progress of the project.
