The Solar-B EUV Imaging Spectrometer: an Overview of EIS

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The Solar-B EUV Imaging Spectrometeran Overview
of EIS

• J. L. Culhane
• Mullard Space Science Laboratory
• University College London

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EIS Optical Diagram
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EIS Calibration

• Each element measured independently at Brookhaven
• Complete instrument calibrated end-to-end at RAL
• Instrument contamination budget maintained by
  keeping at positive dry Nitrogen pressure
• Continuous QCM monitoring pre and post launch
• Temperature insensitive lines in QS measured
  throughout mission
• Two GSFC EUNIS rocket flights during mission
• Philosophy based on SOHO CDS approach.

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EIS Effective Area
Primary and Grating Measured - flight model data
used Filters Measured - flight
entrance and rear filters CCD QE
Measured - engineering model data used Following
the instrument end-to-end calibration, analysis
indicates that the above data are representative
of the flight instrument
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Spectroscopic Performance Long Wavelength Band

• Ne III lines near 267 Å from the NRL NeMg
  Penning discharge source
• Gaussian profile fitting gives the FWHM values
  shown in the right-hand panel

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Spectroscopic Performance Short Wavelength Band

• Mg III lines near 187 Å from the NRL NeMg
  Penning discharge source
• Gaussian profile fitting gives the FWHM values
  shown in the right-hand panel

• Following further new line identifications in
  the Penning source spectrum, an absolute
• wavelength scale may be possible

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• END OF TALK

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Observables

• Observation of single lines
• Line intensity and profile
• Line shift (??) ? Doppler motion
• Line width (?w) and temperature
• ? Nonthermal motion
• Observation of line pair ratios
• Temperature
• Density
• Observation of multiple lines
• Differential emission measure

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EIS Field-of-View
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EIS Sensitivity
Detected photons per 1??1? area of the Sun per 1
sec exposure.
Ion Wavelength (A) logT Nphotons Nphotons
Ion Wavelength (A) logT AR M2-Flare
Fe XVI 251.07 6.40 - 108
Fe XXII 253.16 7.11 - 71
Fe XVII 254.87 6.60 - 109
Fe XXVI 255.10 7.30 - 3.3?103
He II 256.32 4.70 16 3.6?103
Si X 258.37 6.11 14 62
Fe XVI 262.98 6.40 15 437
Fe XXIII 263.76 7.20 - 1.2?103
Fe XIV 264.78 6.30 20 217
Fe XIV 270.51 6.30 17 104
Fe XIV 274.20 6.30 14 76
Fe XV 284.16 6.35 111 1.5?103
Ion Wavelength (A) logT Nphotons Nphotons
Ion Wavelength (A) logT AR M2-Flare
Fe X 184.54 6.00 15 36
Fe XII 186.85 / 186.88 6.11 13/21 105/130
Fe XXI 187.89 7.00 - 346
Fe XI 188.23 / 188.30 6.11 41 / 15 110/47
Fe XXIV 192.04 7.30 - 4.0?104
Fe XII 192.39 6.11 46 120
Ca XVII 192.82 6.70 31 1.8?103
Fe XII 193.52 6.11 135 305
Fe XII 195.12 / 195.13 6.11 241/16 538/133
Fe XIII 200.02 6.20 20 113
Fe XIII 202.04 6.20 35 82
Fe XIII 203.80 / 203.83 6.20 7/20 38/114
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Doppler Velocity and Line Width Uncertainties

• One-s uncertainty in
• - Doppler shift (dv in km/s)
• - Non-thermal line width
• (d FWHM in km/s)
• Values are plotted against
• number of detected photons
• in the line for
• - Bright AR line
• (Fe XV/284 Å)
• - Flare line
• (Fe XXIV/255 Å)

Photons (1??1? area)-1 sec
Photons (1??1? area)-1 (10sec)-1
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First 90 Day Observing Plan

• Flare Trigger and Dynamics
• Spatial determination of evaporation and
  turbulence in a flare
• Active Region Heating
• Spatial determination of velocity field in AR
  loops for a range of Te values
• Quiet Sun Studies
• Correlate coronal Te, ne, v with the magnetic
  topology inferred from FPP
• Coronal Holes and Hole Boundaries
• Measurement of intensity and velocity field at a
  coronal hole boundary and at selected sites in
  coronal holes

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SUMMARY

• Following SOHO CDS, the EIS instrument will
  provide the next steps in EUV spectral imaging of
  the corona
• x 10 enhancement in Aeff from use of multilayers
  and CCDs
• x 5 enhancement in spectral resolution
• x 3 enhancement in spatial resolution
• Like CDS absolute calibration performed to 20
• EIS will
• Address a broad range of coronal science topics
• Enable major goals of Solar-B mission by relating
  coronal response to magnetic flux emergence and
  material flows

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EIS - Instrument Features

• Large Effective Area in two EUV bands 170-210 Å
  and 250-290 Å
• Multi-layer Mirror (15 cm dia ) and Grating both
  with optimized Mo/Si Coatings
• CCD camera Two 2048 x 1024 high QE back
  illuminated CCDs
• Spatial resolution 1 arc sec pixels/2 arc sec
  resolution
• Line spectroscopy with 25 km/s per pixel
  sampling
• Field of View
• Raster 6 arc min8.5 arc min
• FOV centre moveable E W by 15 arc min
• Wide temperature coverage log T 4.7, 5.4, 6.0
  - 7.3 K
• Simultaneous observation of up to 25
  lines/spectral windows

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EIS on the Solar-B Spacecraft Roles and
Responsibilities
UK (MSSL (PI), Birmingham, RAL) ? CCD cameras,
Structure, On-board Processor,
Filter Housing, Calibration USA (NRL, GSFC,
Columbia) ? Optics, Coatings, Mechanisms,
Filters, Japan (NAOJ, ISAS) ? Testing,
Integration with Spacecraft Norway (UiO)
? EGSE Software
All participants are involved in Post-launch
Mission Operations and Data Analysis
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Processed Science Data Products

• Intensity Maps (Te, ne)
• images of region being rastered from the
  zeroth moments of
• strongest spectral lines
• Doppler Shift Maps (Bulk Velocity)
• images of region being rastered from
  first moments of the
• strongest spectral lines
• Line Width Maps (Non-thermal Velocity)
• images of region being rastered from second
  moments of the
• strongest spectral lines

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Doppler Velocity and Line Width Uncertainties
Photons (1??1? area)-1 sec-1 Photons
(1??1? area)-1 (10sec)-1
Number of detected photons
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Primary Mirror Assembly

• Multilayer-coated mirror
• shown installed in the
• instrument structure

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Grating Assembly
Grating
Focus Drive
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Atomic Force Microscope Profile of Laminar
Grating

• AFM profile of grating grooves in a
• 1 µm x 1 µm region near grating center
• for grating FL-8

• .
• Mean groove depth is 6.4 nm and the
• land width is 108 nm (4200 lines/mm)

• Grating substrates fabricated by Zeiss
• - Holographic technique used to form a
• sinusoidal groove pattern
• - Ion beam etching used to shape laminar
• grooves and to achieve specified groove
  depth

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CCD Camera and Readout Electronics
Camera and associated electronics installed in
the instrument structure
CCDs with cold finger attachments
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Slit/Slot and Shutter Assembly
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EIS Instrument Pre-Calibration