arXiv subjects

S. Lion

Publications and source records attributed to S. Lion.

2 recordsLinked to original sources

arXiv2026

The SVOM French Science Center Infrastructure

At the heart of the SVOM French ground segment, the French Science Center is a cloud-based platform which provides services and tools for the management, storage, scientific processing and visualization of SVOM data for the French community. This digital center is a critical node of the SVOM system since it is the single point of access to SVOM scientific data for the French community and the only component of the ground system connected to the SVOM VHF network allowing near-time communication from the satellite. Scientific processing pipelines are fully integrated into its infrastructure, allowing the automated production of high-level scientific data and the generation and broadcast of alerts to the scientific community at large. The software components of the French Science Center are running 24/7 and thus require a high level of automation, which led to the development of dedicated software relying on modern technical solutions such as micro-services, application containerization, infrastructure-as-code and continuous integration and deployment. In this paper, we describe the FSC infrastructure design, technological choices, and the process of SVOM data ingestion, archiving, and automated processing by the FSC scientific pipelines. We present analysis on the FSC performances in terms of availability, amount of data processed as well as processing speed.

astro-ph.IM↗

arXiv2017

Coherent structures at ion scales in fast solar wind: {\it Cluster} observations

We investigate the nature of magnetic turbulent fluctuations, around ion characteristic scales, in a fast solar wind stream, by using {\it Cluster} data. Contrarily to slow solar wind, where both Alfvénic ($δb_{\perp} \gg δb_{\parallel}$) and compressive ($δb_{\parallel} \gg δb_{\perp}$) coherent structures are observed \cite[]{per16}, the turbulent cascade of fast solar wind is dominated by Alfvénic structures, namely Alfvén vortices, with small and/or finite compressive part, with the presence also of several current sheets aligned with the local magnetic field. Several examples of vortex chains are also recognized. Although an increase of magnetic compressibility around ion scales is observed also for fast solar wind, no strongly compressive structures are found, meaning that the nature of the slow and fast winds is intrinsically different. Multi-spacecraft analysis applied to this interval of fast wind indicate that the coherent structures are almost convected by the flow and aligned with the local magnetic field, i.e. their normal is perpendicular to {\bf B}, that is consistent with a two dimensional turbulence picture. Understanding intermittency and the related generation of coherent structures could provide a key insight into the nonlinear energy transfer and dissipation processes in magnetized and collisionless plasmas.

physics.plasm-ph↗