Response of beryllium to deuterium plasma bombardment

Experiments have been conducted in the PISCES-B device to investigate the erosion and deuterium retention characteristics of beryllium. The impurity fractions of both carbon and oxygen in a deuterium plasma have been reduced to 0.2% for carbon and 0.2% or less for oxygen. Under these conditions, the measured sputtering yield of the beryllium samples agrees with beryllium-oxide sputtering. The clean plasma conditions allow for investigation of the surface morphology of the samples under various exposure conditions. During high-temperature exposure the surface develops a porous structure, unlike the smooth surface resulting from low-temperature exposures. The hydrogen isotope retention characteristics of beryllium are measured under conditions which simulate the ITER first wall and baffle plasma interaction regions. The beryllium samples develop a saturated surface layer under these high-flux bombardment conditions. Thermal desorption spectroscopy (TDS) is used to measure the release temperature of the retained deuterium. The TMAP4 code is used to model the deuterium release from the beryllium.