Design and implementation of an ion beam energy degrader for use in the study of nuclear materials

A new design for an ion beam energy degrader has been developed and tested at the Reactor Materials Testing Laboratory at Queen`s University. With the use of a dual rack multi-foil system, it is now possible to implant helium uniformly throughout a nickel target to a depth of 33 µm with helium ions. Aluminium foils are used in the degrader with thicknesses ranging from 2–84 µm, causing deceleration of the incident particle and thus a shallower penetration depth in the target with increased Al foil thickness. The design was successfully tested with the helium implantation of nickel superalloy, Inconel X-750. Using transmission electron microscopy, helium bubbles were imaged following an implantation of 8000 appm helium. A continuous formation of helium bubbles was observed with implantation depth, matching the predicted implantation range. The prediction for helium implantation using the aluminium foils to degrade the incident particle is carried out with data generated from SRIM calculations and an inhouse optimization code.