K. W. Lachenberg, S. D. Stecker, R. C. Salo, Sciaky, Inc., Chicago, IL; J. W. Elmer, Lawrence Livermore National Laboratory, Livermore, CA
Introduction
The development of diagnostic tools for characterizing electron beams has been growing in prominence. The Enhanced Modified Faraday Cup (EMFC) also known as EB-Profiler, developed at Lawrence Livermore National Laboratory (LLNL) and licensed by Sciaky to build, provides measurements of the general size and shape of the beam and the power density distribution across its width. This tool has been utilized in a number of applications, including the characterization of machine performance and repeatability for electron beam welding (EBW) equipment, the transfer of parameters between welders at remote locations, and as a process control tool. The EB-Profiler is proving to be a useful tool in monitoring & diagnosing EBFFF performance.
Results/Discussion
Previous work with the EB-Profiler has been limited to high voltage (150 kV) machines with fixed guns. In this work, the use of the EB-Profiler tool has been expanded to include enhanced low voltage (60 kV) EBW/EBFFF machines with moveable gun configurations designed and manufactured by Sciaky, Inc. Tests have been performed at Sciaky on machines with different configurations and process conditions. Variations in the characteristics of the beams produced by the different generation machines and the differences in sharp focus beams at various work distances will be discussed. The utility of the diagnostic tool in providing a better understanding of the operation of the equipment to improve, monitor and control the EBFFF process will be presented. The outputs from the EB-Profiler include peak power density and through computer tomographic reconstruction, a 3D model of the energy distribution. Differences in output can be a result of many factors including differences in vacuum levels and other operating conditions. Once a process has been qualified, diagnostic tools of this type will insure that the process is properly maintained in production.
Summary: The development of diagnostic tools for characterizing electron beams is proving to be useful in monitoring and diagnosing Electron Beam Free Form Fabrication performance. The use of the diagnostic tool (EB-Profiler) in providing a better understanding of the EBFFF process will be presented.
