THROUGHPUT OF A NORMAL INCIDENCE SPECTROMETER DESIGN IN DIFFERENT WAVELENGTH RANGES Luca Teriaca Max Planck Institut für Sonnensystemforschung

Expected throughput for spatially resolved observations. A=3.848×10 −3 m 2, area of the entrance aperture (primary mirror of D=7 cm). S=2.56×10 10 m 2, area of the solar surface imaged over one pixel at perihelion (160×160 km 2 ) by EUS. Equivalent to 1″/pixel angular scale. r=3.2912×10 10 m, Solar Orbiter–Sun distance at perihelion (0.22 AU). R P (λ)=Reflectance of the primary SiC mirror. R G (λ)=Reflectance of the concave variable line-spacing SiC grating (diffraction efficiency times SiC reflectance). V(λ)=Slit vignetting. Here a 1” wide slit is assumed. D QE (λ)=Detector quantum efficiency. L(λ)=Spectral radiance (ph m –2 s –1 sr –1 nm –1 ). Both average quiet Sun and active region spectra are considered. ΔλΔλ=Spectral resolution element. A value of nm is assumed.

Reflectance of SiC mirrors

Bare and KBr-coated MCPs

Grating diffraction efficiency (SUMER) λ (nm) efficiency (%) efficiencies at higher orders are taken equal to that of the first order

1165 – 1265 Å: Quiet Sun

1165 – 1265 Å: Active Region

950 – 1050 Å: Quiet Sun C III H I Ly γ H I Ly β O VI Si XII

950 – 1050 Å: Quiet Sun C III H I Ly γ H I Ly β O VI Si XII

950 – 1050 Å: Active Region Fe XVI Si XII

950 – 1050 Å: Active Region Fe XVI Si XII

700 – 800 Å: Quiet Sun O III O II O V Ne VIII O IV N IV S V Mg IX

700 – 800 Å: Quiet Sun O III O II O V Ne VIII O IV N IV S V Mg IX

700 – 800 Å: Active Region O III O II O V Ne VIII O IV N IV S V Fe XVI Mg IX

700 – 800 Å: Active Region O III O II O V Ne VIII O IV N IV S V Fe XVI Mg IX