EUS NI spectrograph design constraints Contents: design of normal-incidence spectrograph with ZEMAX optical quality of the single-mirror off-axis telescope possibility of three wavelength ranges between 58 nm and 126.8 nm design of focal plane with 116.8 nm to 126.8 nm channel some thoughts on thermal aspects: Semi-transparent telescope mirror Heat rejection mirror Udo Schühle Max-Planck-Institute for Solar System Research Solar Orbiter 5th EUS consortium Meeting at RAL on 3. March 2006 Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

normal-incidence design optical calculations Based on previous design of Roger Thomas: development of varied-line-space grating surface for ZEMAX ZEMAX calculation with ellipsoid VLS grating modified RT design for longer wavelength channel verified the design complies with specs some possible thermal design solutions Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Design of NI spectrograph off axis parabola telescope: aperture size: 70 mm distance from vertex: 50 mm focal length: 700 mm image scale: 1arcsec = 3.4 microns spectrograph: grating: varied-line-space on ellipsoid magnification: 3.6 image scale: 12 mm/arcsec dispersion: 5 A/mm spectral scale: 60 mA/12mm (40 mA/8mm) Design of NI spectrograph 1 arcsec Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Design of single-mirror telescope off axis parabola telescope: aperture size: 70 mm distance from vertex: 50 mm focal length: 700 mm image scale: 1arcsec = 3.4 microns 1 arcsec 1 arcsec Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Accommodation of three wavelength bands possible? favoured wavelength ranges : 52 nm – 63 nm 72 nm – 80 nm 97 nm – 104 nm 116.5 nm – 126.8 nm possible with siliconcarbide optics normal incidence design with three wavelength ranges from 58.0nm to 126.8nm Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Accommodation of three wavelength bands possible! slit 71.0 nm 80.0 nm 250 mm 97.0 nm 104.5 nm TVLS grating 116.5 nm (58 nm) 126.8 nm (63 nm) 700 mm Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Accommodation of long-wavelength band Si III C III N V C I Si I Mg X Mg X O V He I O IV Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Accommodation of long-wavelength band More useful dynamic range with selective photocathode distribution Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006 Presentation of wavelength channels to be given by Luca Teriaca

Study of a dichroic telescope mirror for 58 nm up mirror coating for wavelengths 58 nm and up: SiC (CVD, hex) a thin coating of ~10 nm provides good VUV reflectivity of 35% to 45% longer wavelengths can be transmitted by a transparent substrate mirror temperature can be minimised detailed thermal study is possible.  dichroic telescope mirror can transmit 90% of the heat! Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Study of a dichroic telescope mirror for 58 nm up Calculations of David Windt 2001 using optical constants of SiC Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Study of a dichroic telescope mirror for 58 nm up 10 nm SiC on LiF substrate* independent study is ongoing with samples of SiO2 and SiC coating of 5 nm, 10 nm, 20 nm thickness * calculation using optical constants of Palik et al. ==> heat will be transmitted towards a radiator Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Design of single-mirror telescope: heat rejection mirror and baffle field of incident radiation at slit plane: +-2.6° (= size of solar image + pointing range) corresponds to circular range of 64 mm diameter! unpredictable thermal distortions during orbit and pointing changes unpredictable stray light in front of the spectrometer slit  toroidal pre-slit mirror Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Design of single-mirror telescope: heat rejection mirror and baffle radiator radiator toroidal heat rejection mirror Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006

Thermal baffle design requires space for heat rejection mirror 900 mm 70 mm slit 75.0 nm 85.0 nm 250 mm 97.0 nm 104.0 nm TVLS grating 116.5 nm (58 nm) 126.8 nm (63 nm) heat rejection mirror 700 mm Udo Schühle 5. Solar Orbiter EUS Consortium Meeting RAL, 3. March 2006