PHEBUS FASE E 2017 (DFM.AD005.205)

Area tematica

Scienze fisiche e tecnologie della materia

Area progettuale

Struttura responsabile del progetto di ricerca

Istituto di fotonica e nanotecnologie (IFN)

Responsabile di progetto

MARIAGUGLIELMINA PELIZZO
Telefono: 049-9819581
E-mail: pelizzo@dei.unipd.it

Abstract

PHEBUS is a double spectrometer (Chassefiere 2010) working in the Extreme UltraViolet (EUV) and Far UltraViolet (FUV) spectral ranges that will investigate the composition and dynamic of Mercury's exosphere on board of the BepiColombo Mission. Its distinctive feature is to work in the EUV region allowing for the first time observations of additional species like He, Ar, N, etc (Chassefiere 2010, Yoshioka 2008). It consists of two distinct channels working in the EUV (55-155 nm) and FUV (145-315 nm) spectral ranges with an extension for two extra visible lines at 404.7 nm and 422.8 nm. The optical scheme includes two drawing blocks: the collecting and the spectrometer parts. The collecting one is composed of the straylight rejection baffle, the primary mirror and the entrance slit. The mirror is an off-axis parabolic mirror, 50° incidence angle and 170 mm focal length. The mirror is positioned at the baffle exit and accommodated inside a scanner rotating mechanism. The main function of the scanner mechanism is to point the spectrometer's line-of-sight selected for the observations and provides the whole coverage of the Mercury exosphere to fulfill the scientific objectives of PHEBUS

Obiettivi

The spectrometer part is instead composed by two channel, the EUV and the FUV one. Two holographic gratings share the same mechanical mount and are accommodated in front of the slit. The light is then diffracted and collected by two Multi Channel Plates detectors. The aberration corrected holographic gratings of PHEBUS are made of aluminum covered by platinum coating. The holograph process has been adopted in order to obtain a Variable Line Space gratings with a mean groove density of 1600 grooves/mm for the FUV grating and 2700 grooves/mm for the EUV one respectively. The groove profiles are laminar ion-etched optimized for the respective spectral range. The purpose of the calibration activities planned for Probing of Hermean Exosphere By Ultraviolet Spectroscopy (PHEBUS) is to define a complete and versatile radiometric model. The ground calibration activities include the characterization of the optical subsystems along time (i.e. including aging and ions irradiation effects), and the measure of the efficiency and geometrical acceptance in term of étendue at the full instrument level. The purpose of such calibration is the development of a full radiometric model in which all th

Data inizio attività

01/11/2017

Parole chiave

spectrometer, extreme ultraviolet, space instrumentation

Ultimo aggiornamento: 28/04/2025