MEASUREMENTS AND MODELING OF THE ANGULAR-RESOLVED SPUTTERING YIELD OFD-SOAKED BE BY 100, 300, 500 AND 700 EV D+

The angular-resolved sputtering yield of Be by D+ was predicted and th en measured. An ion beam at 100, 300, 500 and 700 eV from a Colutron i on source was focused onto S-65 C grade Be samples. The sample was exp osed in situ to a 350 V de D plasma to remove oxide, load the surface with D and more-nearly simulate the surface which would be found durin g steady-state fusion device operating conditions. The angular distrib ution of the sputtered atoms was measured by collection on a highly or dered pyrolytic graphite witness plate. The areal density of Be (and B eO, after exposure to air) was then measured using a scanning Auger sp ectrometer. Total deposition was measured by deposition onto a quartz crystal oscillator placed alongside the witness plate. A three-dimensi onal version of vectorized fractal TRIM (VFTRIM3D). a Monte-Carlo comp uter code which includes surface roughness characterized by fractal ge ometry, was used to predict the angular distribution of the sputtered particles and a global sputtering coefficient, One-quarter million tra jectories were simulated to determine the azimuthal and polar angle di stributions of the sputtered atoms. A fractal dimension of 2.05, and a surface binding energy of 3.38 eV, both standard values for Be, were used. Results show reasonable agreement between the code and experimen tal values for total yield with the experimental yields somewhat lower . The measured angular distribution is broader (less forward peaked) t han predicted by the computer simulation.