The role of beryllium deuteride in plasma-beryllium interactions

Beryllium deuteride has been measured in plasma-exposed surfaces and in the plasma column of the PISCES-B experiment. XPS measurements of high-purity BeH2 samples, used as standards, confirm the presence of beryllium deuteride in beryllium codeposited material (Be 1s energy of BeH2 bond = 115.0 eV). TDS measurements of high-purity BeD2 samples are used to accurately determine the decomposition temperature of the beryllium deuteride molecule (∼540 K). Deuterium release is observed from plasma-exposed beryllium samples and from Be codeposited layers at this temperature. BeD molecular (A–X) band emission is observed in beryllium seeded plasma discharges and during deuterium sputtering measurements of beryllium. Band emission intensities during Be-seeding are used to estimate the photon emission coefficient, <σv>, for the band. The <σv> value verifies that molecular sputtering of BeD (from beryllium targets saturated with deuterium from the plasma exposure) is a small fraction of the physical sputtering of beryllium atoms.