SOLAR ORBITER: Extreme Ultraviolet Imager 12 avril 2005 PNST, IAP

Contenu Objectifs scientifiques Instrument Points durs

Questions fondamentales Quels sont les processus fondamentaux présents dans l’atmosphère solaire et l’héliosphère? Pourquoi le Soleil varie-t-il et comment la dynamo solaire fonctionne-t-elle? Quel est le lien entre le champ magnétique de la couronne et le flux de particules dans l’héliosphère? Ces questions sont pernitentes pour l’Astrophysique en général

Résoudre les échelles fondamentales SOHO/EIT TRACE Futur Chromosphère Chromosphère Chromosphère 1850 km pixels 350 km pixels 70 km pixels Résoudre les échelles spatiales telles que le libre parcours moyen du photon, la hauteur d’échelle et le diamètre des tubes de champ magnétique

Concept de l’EUI

EUV Imager (EUI) Overview Imaging of the sun disk in EUV Resolution/sampling = 0.5 arc-sec Field of view = 2.7° (sun angular diameter at 0.21 AU) Two instruments: HRI for resolution: 0.5 arc-sec in 17 arc-min field (2k x 2k detector array) FSI for field: 4.75 arc-sec (  9.5 arc-sec) in 5.4° field (4k x 4k); field of FSI is twice the sun angular diameter to account for HRI depointing HRI spectral bands: 13.3 nm, 17.4 nm, 30.4 nm  3 different HRI telescopes optimised for each spectral band FSI spectral bands: TBD in 17.1 – 30.4 nm  single telescope Diameter of HRIs and FSI = driven by radiometry and not diffraction (FSI 5 mm, HRI 30 mm)

EUV Imager (EUI) Functional block diagram aperture door mechanism detector front end electronics back end electronics 28 V EUV filter telescope field stop relay optics baffle

EUV Imager (EUI) HRI and FSI configurations HRI : single structure ("optical bench") for all 3 telescopes baffles thermally decoupled from the "optical bench" to minimise heat-flux and thermoelastic distortion FSI : baffle decoupled from optical bench filter supported by baffle

EUV Imager (EUI): interfaces HRI sampling field diameter 0.5 arc-sec 17 arc-min 30 mm FSI sampling field diameter 9.5 arc-sec 5.4° 5 mm focal plane2k x 2k volume 900 x 110 x x 250 x 190 mass*20 kg Power25 W * excluding window, enclosure & radiators& other ancillary equipment

EUV Imager (EUI): Points durs Heat rejection of EUV filters and baffles EUV Detectors (as EUS) back-thinned CMOS 4 k x 4 k  2 k x 2 k format with 9 µm pixels alternative detectors : Diamond or GaN/AlGaN  credible in large format ? Cooling of CMOS detectors at – 80°C Telemetry: huge compression or data selection required