Nano-Crystalline Diamond-Carbon Multi Layer Stripper Foils

Next-generation, nuclear physics research facilities, including the Rare Isotope Accelerator (RIA), will have much higher beam power densities (2,000-3,000 kW/cm2). This will require significant improvements to the currently-used stripper foils. In previous work, it was demonstrated that a three-layer, nano-crystalline, diamond-carbon stripper foil, made with a combination of pulse arc deposition (which produces tensile stressed layers) and pulse laser deposition (which produces compressively stressed layers) techniques, increased the lifetime of stripper foils to as much as 100 coulombs per foil. This project will scale up this technology by increasing the number of layers to control the stress in the foils, thereby enabling the manufacture of thicker, self-supporting diamond foils (as thick as 20mg/cm2) with longer lifetime. In Phase I, the pulse laser system will be modified to add an arc source, enabling the continuous fabrication of alternate layers in a single vacuum system. The stress in each layer, as well as for the total foil, will be monitored so as to produce nearly zero total stress, thereby reducing the curling and fracture of foils during fabrication. A large number of foils with different layer thicknesses and number of layers will be fabricated and tested at various high-energy accelerator facilities. Commercial Applications And Other Benefits as described by the Applicant: The improved stripper foils should have a very significant impact on the operating conditions of next generation nuclear accelerator facilities, not only for scientific research but also for medical and commercial isotope manufacturing. As an example, the radio-pharmaceuticals manufactured in these facilities are used to treat (by radiation therapy) millions of people with cancer around the world. Other future R&D applications of this thin-film coating technology include fabrication of hard, wear resistant diamond coatings for cutting tools and moving parts; free standing films for x-ray windows; and scratch resistant diamond coatings for various types of optics, including eyeglasses.