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We report measurements of total C sputtering yields for amorphous deuterated carbon thin films irrradiated by equal velocity D + , D 2 + , and D 3 + beams in the energy range 30-200 eV/D. The C sputtering yields were deduced from crater volumes determined from 2-D ellipsometry scans, the known thin film C density, and the measured total number of incident D particles during the beam exposures. While our results for incident D 3 + ions are in good agreement with mass loss measurements for D 3 + , our results for D 2 + and D + incident ions fall systematically below the D 3 + results, indicating a significant molecular size effect. A molecular size effect has been previously found for CD 4 production during low energy impact of same-velocity D + , D 2 + , and D 3 + ions incident on ATJ graphite, which, however, was smaller in magnitude. The total C sputtering yields obtained from ellipsometry are in reasonable agreement with recently deduced total C production yields based on a mass spectroscopy approach.

We have obtained estimates of plasma potentials and energy spreads characterizing an electron cyclotron resonance ion source plasma under different source conditions. Our estimates are obtained from analysis of ion beams extracted from the ion source at 10 kV that are subsequently decelerated into a floating surface scattering chamber where their current intensity incident on a solid sample is measured as function of retardation voltage. The deceleration occurs outside the measurement chamber, permitting beam current measurements in a field-free region. Absence of grids in the deceleration section avoids potential issues of field penetration. The behavior of our deceleration optics was modeled with SIMION. The simulation indicated a linear beam attenuation dependence close to full retardation where the beam current goes to zero. Deviations from this linear dependence observed close to zero beam energy give information on the initial energy spread of the ions extracted from the source. Our decelerated beams measurements are compared with recent in situ probe results and external beams results based on magnetic analysis.

Articles you may be interested in X-ray enhanced sputter rates in argon cluster ion sputter-depth profiling of polymersa) Formation of doubly positively charged diatomic ions of Mo 2 2+ produced by Ar + sputtering of an Mo metal surface Abstract. In this paper the sputtering of lunar regolith by protons and solar wind heavy ions is considered. From preliminary measurements of H + , Ar +1 , Ar +6 and Ar +9 ion sputtering of JSC-1A AGGL lunar regolith simulant at solar wind velocities, and TRIM simulations of kinetic sputtering yields, the relative contributions of kinetic and potential sputtering contributions are estimated. An 80-fold enhancement of oxygen sputtering by Ar + over same-velocity H + , and an additional x2 increase for Ar +9 over same-velocity Ar + was measured. This enhancement persisted to the maximum fluences investigated (~10 16 /cm 2 ). Modeling studies including the enhanced oxygen ejection by potential sputtering due to the minority heavy ion multicharged ion solar wind component, and the kinetic sputtering contribution of all solar wind constituents, as determined from TRIM sputtering simulations, indicate an overall 35% reduction of near-surface oxygen abundance. XPS analyses of simulant samples exposed to singly and multicharged Ar ions show the characteristic signature of reduced (metallic) Fe, consistent with the preferential ejection of oxygen atoms that can occur in potential sputtering of some metal oxides.