Be–W alloy formation in static and divertor-plasma simulator experiments

Collaborative Be–W interaction experiments conducted at UC-San Diego PISCES Laboratory, and Sandia National Laboratories, Livermore, CA (SNL/CA), are reported. In the divertor-plasma simulator PISCES–B, W targets are exposed to Be seeded D2 plasma in the temperature range 1070–1320K. All reveal the formation of surface Be–W alloying. The alloy reaction rate is found to increase with surface temperature in the range 1023–1123K in SNL vacuum-deposition phase formation experiments. In both sets of experiments the efficiency of surface alloying is found to depend on the availability of surface deposited Be. This availability is reduced by evaporation at high temperature, and also by plasma re-erosion in the case of PISCES–B targets. Surface analysis of targets using Auger electron spectroscopy (AES), wavelength dispersive X-ray spectroscopy (WDS), and X-ray diffraction (XRD) reveals Be12W as the dominant alloy composition where Be surface availability is optimal.