THROUGHPUT OF A NORMAL INCIDENCE SPECTROMETER

DESIGN IN DIFFERENT WAVELENGTH RANGES

Luca TeriacaMax Planck Institut für Sonnensystemforschung

Expected throughput for spatiallyresolved observations.

A = 3.848×10−3 m2, area of the entrance aperture (primary mirror of D=7 cm).

S = 2.56×1010 m2, area of the solar surface imaged over one pixel at perihelion (160×160 km2) by EUS. Equivalent to 1″/pixel angular scale.

r = 3.2912×1010 m, Solar Orbiter–Sun distance at perihelion (0.22 AU).

RP(λ) = Reflectance of the primary SiC mirror.

RG(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.

DQE(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.

Δλ = Spectral resolution element. A value of 0.005 nm is assumed.

LDVRRr

SA

t

NQEGP2

Reflectance of SiC mirrors

Bare and KBr-coated MCPs

Grating diffraction efficiency (SUMER)

λ (nm) efficiency (%) 77 17100 28122 28

efficiencies at higher orders are taken equal to that of the first order

1165 – 1265 Å: Quiet Sun

1165 – 1265 Å: Quiet Sun

1165 – 1265 Å: Quiet Sun

1165 – 1265 Å: Active Region

1165 – 1265 Å: Active Region

1165 – 1265 Å: Active Region

950 – 1050 Å: Quiet Sun

C III

H I Ly γ H I Ly β O VI

Si XII Si XII

950 – 1050 Å: Quiet Sun

C III

H I Ly γH I Ly β O VI

Si XII Si XII

950 – 1050 Å: Active Region

Fe XVI

Si XII Si XII

950 – 1050 Å: Active Region

Fe XVI

Si XII 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