Periodic Surface Morphology Characteristics of Tungsten Under Simultaneous Helium and Deuterium Bombardment at 30 keV

Abstract

The ITER divertor will feature tungsten monoblocks as the plasma-facing component (PFC) that will be subject to extreme temperature and radiation environments. This paper reports the development of surface morphologies on tungsten under helium bombardment at high temperatures, which has important implications for safety, retention, and PFC erosion. Polycrystalline tungsten samples were implanted in the Dual Advanced Ion Simultaneous Implantation Experiment dual-beam ion implantation experiment at the University of Wisconsin-Madison with He-only and simultaneous He-D implantation at incidence angles of 55 deg, ion energies of 30 keV, and surface temperatures of 900°C to 1100°C. Morphologies resulting from angled incidence conditions differed from those produced under normal incidence bombardment at similar energy and temperature conditions in previous work. A variety of ordered and disordered morphologies dependent on grain orientation were observed for fluences up to 6 × 10¹⁸ He cm⁻². These morphologies displayed dependencies on crystal orientation at low fluences and incident beam directions at higher fluences. These structures appeared, with variation, under both single-species He and mixed He-D implantations.

Keywords:

• Tungsten
• helium
• morphology
• plasma-facing component

Acknowledgments

This work has been funded in part by the University of Wisconsin, Grainger Foundation, Greatbatch Foundation, and TAE Technologies. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.