| 1. |
- Biber, Herbert, et al.
(author)
-
Solar wind Helium ion interaction with Mg and Fe rich pyroxene as Mercury surface analogue
- 2020
-
In: Nuclear Instruments and Methods in Physics Research Section B. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 480, s. 10-15
-
Journal article (peer-reviewed)abstract
- The surface of Mercury is continuously exposed to impinging solar wind ions. To improve the understanding of space weathering and exosphere formation, a detailed investigation of the ion-surface interaction is necessary. Magnesium and iron rich pyroxene (Ca,Mg,Fe)(2)[Si2O6] samples were used as analogues for Mercury's surface and irradiated with He+ ions at solar wind energies of 4 keV. Several regimes of implantation and sputtering were observed there. The total estimated mass of implanted He coincides with the mass decrease due to He outgassing during subsequent Thermal Desorption Spectroscopy measurements. Comparison to established modeling efforts and SDTrimSP simulations show that a He saturation concentration of 10 at.% has to be assumed. A complete removal of He is observed by heating to 530 K. On the surface of Mercury, temperatures between about 100 K and 700 K are expected. This temperature will therefore influence the implantation and release of He into Mercury's exosphere.
|
|
| 2. |
- Kantre, Karim-Alexandros, et al.
(author)
-
Combined in-situ ion beam analysis and thermal desorption spectroscopy for studying deuterium retention in tungsten
-
Other publication (other academic/artistic)abstract
- We demonstrate a combinatory approach integrating ion implantation followed by thermal annealing and simultaneous in‑situ ion beam analysis with thermal desorption spectroscopy to be used for investigating the retention of deuterium in tungsten. All sample preparation, modification and analysis steps are performed in a single system. Atomic and molecular deuterium ions of 3 keV were implanted into tungsten bulk samples with highest doses significantly exceeding 1x1022 ions/m2. We demonstrate depth profiling of different hydrogen species by elastic recoil detection analysis, while the outgassing rate of molecular deuterium was simultaneously monitored by thermal desorption spectroscopy in different annealing processes (continuous and stepwise temperature ramping) from room temperature up to ≈1400 K. No pronounced narrow peaks were detected in the thermal desorption spectra regardless of the annealing procedure. The combination of the two techniques in a full in‑situ approach is shown capable to identify the distinct retention behavior of deuterium at different temperatures and in different reservoirs, e.g. located close to the surface and deuterium diffused deeper in the material from a single sample. Simultaneously, protium was detected in small amounts close to the sample surface. Ex-situ scanning electron microscopy analysis confirmed blister formation induced by ion implantation, and a recovery of the initial surface morphological aspect after high temperature annealing, confirming the analogy of our model system to earlier comprehensive ex‑situ studies.
|
|
| 3. |
- Szabo, Paul S., et al.
(author)
-
Dynamic Potential Sputtering of Lunar Analog Material by Solar Wind Ions
- 2020
-
In: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 891:1
-
Journal article (peer-reviewed)abstract
- Pyroxenes ((Ca, Mg, Fe, Mn)(2)Si2O6) belong to the most abundant rock forming minerals that make up the surface of rocky planets and moons. Therefore, sputtering of pyroxenes by solar wind ions has to be considered as a very important process for modifying the surface of planetary bodies. This is increased due to potential sputtering by multiply charged ions; to quantify this effect, sputtering of wollastonite (CaSiO3) by He2+ ions was investigated. Thin films of CaSiO3 deposited on a quartz crystal microbalance were irradiated, allowing precise, in situ, real time sputtering yield measurements. Experimental results were compared with SDTrimSP simulations, which were improved by adapting the used input parameters. On freshly prepared surfaces, He2+ ions show a significant increase in sputtering, as compared to equally fast He+ ions. However, the yield decreases exponentially with fluence, reaching a lower steady state after sputtering of the first few monolayers. Experiments using Ar8+ ions show a similar behavior, which is qualitatively explained by a preferential depletion of surface oxygen due to potential sputtering. A corresponding quantitative model is applied, and the observed potential sputtering behaviors of both He and Ar are reproduced very well. The results of these calculations support the assumption that mainly O atoms are affected by potential sputtering. Based on our findings, we discuss the importance of potential sputtering for the solar wind eroding the lunar surface. Estimated concentration changes and sputtering yields are both in line with previous modeling for other materials, allowing a consistent perspective on the effects of solar wind potential sputtering.
|
|
