Ion scattering experiments on lunar analogs
2024 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Student thesis
Abstract [en]
The Moon is a rocky body, like the Earth, but without a protective atmosphere or magneticfield and is therefore subject to space weathering processes. Sputtering of surface atoms bybombarding projectiles is one such process, accompanied by the scattering of the projectiles.However, few have studied the angular distribution of the sputtered and scattered particles,which is important to understand the proportion of products at any given observation angle.Our experiments were performed to observe a bombarded target surface at observation anglesof 0° to 75° relative to the surface normal. Calcium-rich plagioclase and calcium-richpyroxene rock samples, representing common lunar minerals, were bombarded with ionizedargon and proton projectiles. Proton projectiles were used at 400 eV to 1500 eV energies, andargon ion projectiles at 800 eV to 3000 eV energies. Proton projectiles scattered continuouslyalong the observed angles, at energies between 100 eV to 1100 eV. Few sputtered targetswere observed, at energies below 100 eV. Argon ion projectiles scattered non-uniformlybetween 100 eV and 1100 eV. Observations of scattered projectiles decrease at angles closerto the surface normal. Sputtered targets were observed at energies below 100 eV and werequite homogeneous across their energy and angular range. A classical scattering single-collision model can explain both proton and argon ion scattering, considering scattering targetmasses equivalent to oxygen or a silica-oxygen tetrahedron, respectively. The model cannotexplain the sputtering distributions for either projectile species, potentially due to multiple-collision processes, or chemical effects like bonding strengths not considered in the model.The two rock-types were shown to produce similar scattering and sputtering products.
Place, publisher, year, edition, pages
2024. , p. 34
Keywords [en]
Moon, space weathering, minerals, sputtering, scattering.
National Category
Geosciences, Multidisciplinary
Identifiers
URN: urn:nbn:se:umu:diva-226328OAI: oai:DiVA.org:umu-226328DiVA, id: diva2:1871038
External cooperation
With the Swedish institute of space physics, IRF, Kiruna, with Gabriella Stenberg Wieser
Subject / course
Examensarbete i Geovetenskap/naturgeografi avseende masterexamen
Supervisors
Examiners
2024-08-192024-06-162024-08-19Bibliographically approved