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Science Investigation Goals and Instrument Requirements

Dr. George A. Doschek

EIS US Principal Investigator

Naval Research Laboratory

Phone: 202-767-3527, FAX: 202-404-7997

e-mail: gdoschek@ssd5.nrl.navy.mil

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Solar-B Spacecraft

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Solar Photosphere at 5800 K

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Solar Atmosphere at 105 K

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Solar Atmosphere at 106 K

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Solar Atmosphere >106 K

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Coronal Mass Ejection

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Extreme-Ultraviolet Imaging Spectrometer (EIS)

• EIS Records Solar Extreme-Ultraviolet (EUV) Spectra That Contain Information on the Dynamics, Velocity, Temperature, and Density of the Emitting Plasma

• Spectra Are Obtained With High Spatial Resolution

– Spectra at Many Locations Within an Entire Solar Structure Can Be Recorded

• Spectra Are Obtained With Sufficient Time Resolution to Determine the Dynamics As a Function of Position Within Solar Flare and Active Region Loops

• Spectra Can Be Accurately Related to the Images Obtained From the Solar-B White Light and X-Ray Telescopes

• EIS Is the First EUV Solar Spectrometer Capable of Obtaining High Spectral Resolution Data With Both High Spatial and Temporal Resolution

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EIS Science Objectives

• Determine the Physical Mechanism(s) Responsible for Coronal Heating in the Quiet Sun and Active Regions (Detect Magnetic Reconnection, Wave Heating, Etc.)

• Determine the Physical Mechanism(s) Responsible for Transient Phenomena in the Solar Atmosphere: Explosive Events, Eruptive Prominences, Coronal Mass Ejections, Solar Flares (Determine Energy Transport and Mass Motions in Different Atmospheric Regions During Transient Events)

• Determine the Relationship of Coronal Phenomena to the Dynamics of Photospheric Magnetic Fields (Relate EIS Observations to Data Obtained by the Solar-B White Light and X-Ray Telescopes)

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Simplified Schematic of EIS

SunFilter

GratingPrimary

CCD Long

CCD Short

Slit

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EIS Instrument Requirements for Satisfying the Science Objectives

• Spatial Resolution: EIS Is Required to Resolve Solar Structures Equal to or Less Than 1400 km In Size (2 Arcsec)

• Spectral Resolution: EIS Is Required to Determine Spectral Line Wavelengths to an Accuracy of About 3 km/s, and Is Required to Measure Nonthermal Motions As Small As 20 km/s From Line Widths

• Temporal Resolution: EIS Is Required to Obtain Accurate Measurements of Strong Line Intensities and Line Widths Every 3 s in Highly Dynamic Events Such As Flares, and As Rapidly As Every 10 s in Less Dynamic Phenomena Such As Active Region Loops

• Temperature Coverage: EIS Is Required to Obtain Imaging/Spectral Measurements From Spectral Lines Emitted in the Transition Region (0.1 - 1 MK), Corona (1 - 3 MK), and Hot Portions of Solar Flares (6 - 20 MK)

– This Requires Observations in the Extreme Ultraviolet (EUV)

– The Selected Wavelength Bands Are: 180 - 204 Å and 250 - 290 Å

• Instrument Alignment: EIS Images Are Required to Be Co-Aligned With Images From the Other Solar-B Instruments (Use He II 256 Å)

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Fe XXIV Energy Levels

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Short Wavelength Band

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Long Wavelength Band

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Long Wavelength Band for Different Solar Regions

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Schematic Spectral Line Profiles

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Explosive Event

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Electron Density Sensitive Line Ratios

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Electron Density Above a Polar Coronal Hole

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The EIS Subsystems Provided By NASA

• An Articulated Multi-Layer Coated Telescope Mirror

• A Multi-Layer Coated Grating With Focussing Capability

• A Thin Aluminum Entrance Filter and Mount

• A Post Slit Thin Aluminum Filter and Mount

• A Slit Assembly Mechanism (Interchangeable Slits and a Shutter)