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The Solar-B EUV Imaging Spectrometer: an Overview of EIS. J. L. Culhane Mullard Space Science Laboratory University College London. Primary Mirror. Entrance Filter. CCD Camera. Front Baffle. Grating. EIS Optical Diagram. Each element measured independently at Brookhaven

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


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the solar b euv imaging spectrometer an overview of eis

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

J. L. Culhane

Mullard Space Science Laboratory

University College London

eis optical diagram

Primary Mirror

Entrance Filter

CCD Camera

Front Baffle

Grating

EIS Optical Diagram

EIS Instrument Overview

slide3
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.

EIS Calibration

EIS Instrument Overview

eis effective area
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

EIS Instrument Overview

slide5

l/Dl ~ 4600

57.7 mÅ

58.1 mÅ

57.9 mÅ

Spectroscopic Performance

Long Wavelength Band

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

EIS Instrument Overview

slide6

l/Dl ~ 4000

47 mÅ

47 mÅ

Spectroscopic Performance

Short Wavelength Band

  • Mg III lines near 187 Å from the NRL Ne–Mg 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

EIS Instrument Overview

slide7
END OF TALK

EIS Instrument Overview

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



w

Observables

EIS Instrument Overview

eis field of view

Shift of FOV center with coarse-mirror motion

Maximum FOV for raster observation

360 

900 

900 

512 

512 

512 

Raster-scan range

250 

slot

40 

slot

EIS Slit

EIS Field-of-View

EIS Instrument Overview

eis sensitivity
EIS Sensitivity

Detected photons per 11 area of the Sun per 1 sec exposure.

EIS Instrument Overview

slide11

Flare line

Bright AR line

Doppler velocity

Line width

Doppler Velocity and Line Width Uncertainties

  • One-s uncertainty in:

- Doppler shift (dv in km/s)

- Non-thermal line width

(dFWHM 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

EIS Instrument Overview

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

First 90 Day Observing Plan

EIS Instrument Overview

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

SUMMARY

EIS Instrument Overview

slide14
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 min×8.5 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

EIS - Instrument Features

EIS Instrument Overview

slide15

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

EIS Instrument Overview

processed science data products
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

EIS Instrument Overview

slide17

Flare line

Bright AR line

Doppler velocity

Line width

Doppler Velocity and Line Width Uncertainties

Photons (11 area)-1 sec-1

Photons (11 area)-1 (10sec)-1

Number of detected photons

EIS Instrument Overview

slide18

Raster

Drive

Primary Mirror

Primary Mirror Assembly

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

EIS Instrument Overview

grating assembly
Grating Assembly

Grating

Focus Drive

EIS Instrument Overview

atomic force microscope profile of laminar grating
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

EIS Instrument Overview

slide21

Dual CCD Camera

CCD Camera and Readout Electronics

Camera and associated

electronics installed in the

instrument structure

CCDs with cold finger

attachments

EIS Instrument Overview

slit slot and shutter assembly

Slit/Slot Wheel

- before blackening

Shutter

Slit/Slot Wheel

Slit/Slot and Shutter Assembly

EIS Instrument Overview