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- Bécoulet, A., et al.
(författare)
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Science and technology research and development in support to ITER and the Broader Approach at CEA
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10
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Tidskriftsartikel (refereegranskat)abstract
- In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches, disruption-generated runaway electrons, edge-localized modes (ELMs), the development of imaging surveillance, and heating and current drive systems for steady-state operation. The WEST (W Environment for Steady-state Tokamaks) project, turning Tore Supra into an actively cooled W-divertor platform open to the ITER partners and industries, is presented.
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- Oberst, J., et al.
(författare)
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Planetary polar explorer – the case for a next-generation remote sensing mission to low Mars orbit
- 2022
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 54, s. 695-711
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Tidskriftsartikel (refereegranskat)abstract
- We propose the exploration of polar areas on Mars by a next-generation orbiter mission. In particular, we aim at studying the seasonal and regional variations in snow-deposits, which – in combination with measurements of temporal variations in rotation and gravity field – will improve models of the global planetary CO2 cycle. A monitoring of polar scarps for rock falls and avalanche events may provide insights into the dynamics of ice sheets. The mapping of the complex layering of polar deposits, believed to contain an important record of climate history, may help us understand the early climate collapse on the planet. Hence, we propose an innovative next-generation exploration mission in polar circular Low Mars Orbit, which will be of interest to scientists and challenging to engineers alike. Schemes will be developed to overcome atmosphere drag forces acting upon the spacecraft by an electric propulsion system. Based on the experience of missions of similar type in Earth orbit we believe that a two-year mission in circular orbit is possible at altitudes as low as 150 km. Such a mission opens new opportunities for novel remote sensing approaches, not requiring excessive telescope equipment or power. We anticipate precision altimetry, powerful radars, high-resolution imaging, and magnetic field mapping. © 2022, The Author(s).
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| 7. |
- Pais, V., et al.
(författare)
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Enabling remote access to projects in a large collaborative environment
- 2010
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Ingår i: Fusion Engineering and Design. - : Elsevier BV. - 0920-3796. ; 85:3-4, s. 633 - 636
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Konferensbidrag (refereegranskat)abstract
- In the context of the Integrated Tokamak Modelling Task Force, a large number of software projects are made available to the task force members, including developers and end-users. This has been achieved through a combination of tools and technologies.The front-end is represented by a Java based portal system exposing a PHP project management system, GForge. These two applications are linked by a single sign-on mechanism, Shibboleth [1], and through secure HTTP [2] request rewriting, where appropriate. Furthermore, the underlying storage facility is an OpenAFS [3] distributed file system and the user base comes from both a network information server and an LDAP [4] directory. Security mechanisms are those of a distributed system, with multiple access points and protocols used for reading and writing data.The present paper presents the challenges of integrating these different technologies and programming languages into a single, working, application presented to its users as a web portal. Chaining of the tools is explored through the user perspective, with an in-depth overview of the background transitions between the various systems involved with regard to security requirements for the front-end nodes and the policies as seen by the users.
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| 8. |
- Ramsdale, J. D., et al.
(författare)
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Grid-based mapping: A method for rapidly determining the spatial distributions of small features over very large areas
- 2017
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Ingår i: Planetary and Space Science. - : Elsevier BV. - 0032-0633. ; 140, s. 49-61
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Tidskriftsartikel (refereegranskat)abstract
- The increased volume, spatial resolution, and areal coverage of high-resolution images of Mars over the past 15 years have led to an increased quantity and variety of small-scale landform identifications. Though many such landforms are too small to represent individually on regional-scale maps, determining their presence or absence across large areas helps form the observational basis for developing hypotheses on the geological nature and environmental history of a study area. The combination of improved spatial resolution and near-continuous coverage significantly increases the time required to analyse the data. This becomes problematic when attempting regional or global-scale studies of metre and decametre-scale landforms. Here, we describe an approach for mapping small features (from decimetre to kilometre scale) across large areas, formulated for a project to study the northern plains of Mars, and provide context on how this method was developed and how it can be implemented. Rather than. "mapping" with points and polygons, grid-based mapping uses a "tick box" approach to efficiently record the locations of specific landforms (we use an example suite of glacial landforms; including viscous flow features, the latitude dependant mantle and polygonised ground). A grid of squares (e.g. 20 km by 20 km) is created over the mapping area. Then the basemap data are systematically examined, grid-square by grid-square at full resolution, in order to identify the landforms while recording the presence or absence of selected landforms in each grid-square to determine spatial distributions. The result is a series of grids recording the distribution of all the mapped landforms across the study area. In some ways, these are equivalent to raster images, as they show a continuous distribution-field of the various landforms across a defined (rectangular, in most cases) area. When overlain on context maps, these form a coarse, digital landform map. We find that grid-based mapping provides an efficient solution to the problems of mapping small landforms over large areas, by providing a consistent and standardised approach to spatial data collection. The simplicity of the grid-based mapping approach makes it extremely scalable and workable for group efforts, requiring minimal user experience and producing consistent and repeatable results. The discrete nature of the datasets, simplicity of approach, and divisibility of tasks, open up the possibility for citizen science in which crowdsourcing large grid based mapping areas could be applied.
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- Butcher, Frances E.G., et al.
(författare)
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Eskers associated with buried glaciers in Mars' mid latitudes: recent advances and future directions
- 2022
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Ingår i: Annals of Glaciology. - : Cambridge University Press. - 0260-3055 .- 1727-5644. ; 63:87-89, s. 33-38
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Tidskriftsartikel (refereegranskat)abstract
- Until recently, the influence of basal liquid water on the evolution of buried glaciers in Mars' mid latitudes was assumed to be negligible because the latter stages of Mars' Amazonian period (3 Ga to present) have long been thought to have been similarly cold and dry to today. Recent identifications of several landforms interpreted as eskers associated with these young (100s Ma) glaciers calls this assumption into doubt. They indicate basal melting (at least locally and transiently) of their parent glaciers. Although rare, they demonstrate a more complex mid-to-late Amazonian environment than was previously understood. Here, we discuss several open questions posed by the existence of glacier-linked eskers on Mars, including on their global-scale abundance and distribution, the drivers and dynamics of melting and drainage, and the fate of meltwater upon reaching the ice margin. Such questions provide rich opportunities for collaboration between the Mars and Earth cryosphere research communities.
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