Department: Center for Energy Research (CER)
Sergei Krasheninnikov ; Russell Doerner
Name: Eider Oyarzabal
Email: eoyarzabal @ ferp.ucsd.edu
Grad Year: 2007
Molybdenum and Carbon cluster (C2 and C3) angular sputtering distributions are measured during Xenon ion bombardment from a plasma, with incident ion energy EXe ranging between 75 and 225 eV. These angular sputtering distributions are important in order to model and predict the long term performance of the studied materials in different applications; ion thruster grid materials (Molybdenum and Carbon) and divertor component material in the case of detached plasmas (Carbon). There are only a few studies for energies under 200 eV and no information is available on the angular distribution of sputtered carbon at these low energies. A quadrupole mass spectrometer (QMS) is used to detect the fraction of sputtered neutrals that is ionized in the plasma, and to obtain the angular distribution by changing the angle between the target and the QMS aperture. The angular sputtering distribution for Molybdenum presents a maximum at 60, and this maximum becomes less pronounced as the incident ion energy increases. The dependence of the total sputtering yield on incident ion energy is in good agreement with previous experiments. There is a large increase of about one order of magnitude in the sputtering yield from EXe = 75 to 125 eV, and a more moderate increase for higher energies. Sputtered C2 and C3 clusters exhibit a similar angular sputtering distribution with a maximum at around 60-75 for C2 and around 60for C3; however, this maximum becomes more pronounced for higher incident energies, in contrast to the molybdenum case. The C2 cluster sputtering yield increases by less than one order of magnitude from EXe = 75 to 225 eV while the C3 cluster sputtering presents a maximum at EXe 175 eV. This may be the result of these clusters being less stable during high energy ion bombardment of the surface.
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