''On-line'' analyses of simulated solar wind implantations of terrestrial analogs of lunar materials

To help assess possible water reserves on the moon derived from the solar wind that could supply a lunar base, oligoclase, ilmenite, and simulated lunar glass have been irradiated with a beam of 2.5 keV/amu deuterium ions to simulate solar wind proton bombardment of lunar materials. For ilmenite and simulated lunar glass the areal density of deuterium D(ϕ) (D/cm2) increases with the incident ion fluence ϕ until a critical reemission fluence is reached (ϕ = 3.3–3.5×1017 D/cm2). At this point deuterium begins to be lost from both targets until D(ϕ) reaches a saturation value Ds = 2–4×1017 D/cm2 at ϕ8 = 1–2 × 1018 D/cm2. Oligoclase begins losing deuterium when the beam is turned on; D(ϕ) never reaches a saturation value up to the limit of our experiment (≈ 3×103 D/cm2). There is a small yield of ∼10−4 D2O+/Dincident during the implantation. Thermal release patterns for D2 in our targets do not correspond to those observed for H2 in lunar soils, but the differences may be explainable after further experiments. Although ilmenite stores about twice as much deuterium as the other target materials, it is unknown whether this small enrichment factor will be sufficient to make it a potential source of lunar water.