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- Biber, Herbert, et al.
(författare)
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Solar wind Helium ion interaction with Mg and Fe rich pyroxene as Mercury surface analogue
- 2020
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : ELSEVIER. - 0168-583X .- 1872-9584. ; 480, s. 10-15
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Szabo, Paul S., et al.
(författare)
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Dynamic Potential Sputtering of Lunar Analog Material by Solar Wind Ions
- 2020
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Ingår i: Astrophysical Journal. - : IOP PUBLISHING LTD. - 0004-637X .- 1538-4357. ; 891:1
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Tidskriftsartikel (refereegranskat)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.
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| 3. |
- Gariboldi, Nicola, et al.
(författare)
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CIGRE JWG A3.43 progress report “Tools for lifecycle management of T&D switchgear based on data from condition monitoring systems"
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In March 2019 the joint working group A3.43 "Tools for lifecycle management of T&D switchgear based on data from condition monitoring systems" started its activities with the goal to provide inside three years a guide on how to use the data from monitoring activities of switchgear.The working group counts presently 34 members, from 17 different countries met already five times and work is ongoing on the main Technical Brochure (TB) structure as follows: 1. Executive summary 2. Introduction3. Literature Review4. Condition indicators of T&D switchgear5. Tools and Criteria for lifecycle management and Switchgear Health Index6. Compliance with digital substation for data management7. User’s experiences of end-of-life of T&D switchgear: survey, case studies and interviews8. Future needs and trendsA literature review offers a glimpse into state of the art tools and techniques for lifecycle management and the equipment used. A very steep increase of publications on this matter is observed in the last years with implications in other aspects beyond lifecycle management. Second, the condition indicators as determined in the TB737 are taken over and used in this work as proxies for the switchgear variables evaluation.The main part of the work concentrates on the tools and techniques their framework established. The works from other WG’s on substation level on B3 study committees are introduced as an organic part of the activities. A fundamental decision has been made to follow Health Index concepts as defined in B3.48 concentrating on providing valuable inputs specifically for switchgear. The main focus is on Tools and Criteria for lifecycle management for which the target is to propose models which can condense the specific and deep knowledge of the members to arrive to an advanced and reliable assessment. Some concrete examples are planned to act as guidelines on how to apply the theory to real life scenarios. The digitization of substation equipment is an ongoing process, which is radically changing how assets will be controlled in the substation. IEC 61850 is today the followed standard on which this automation revolution is based for operation and protection. Four members from study committee B5 are part of the group specifically to identify the potential benefit of a technology which has not been driven by monitoring. User experiences are under evaluation. Preliminary results, not presented here, have shown mixed opinions between use and necessity.Finally, the future trends identified so far are discussed. The role of condition monitoring systems as enablers for future developments in the networks is discussed.
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