Model instruments baseline specification and key open issues

EUV/FUV High-Throughput Spectroscopic Telescope

Toshifumi Shimizu

(ISAS/JAXA)

2012.8.13 1SCSDM-4

4th Solar-C Science Definition MeetingAt St. Andrews, U.K.

EUVST’s roles in Solar-C• EUV~FUV spectroscopic telescope (EUVS or EUVST) is a key component for

achieving Solar-C science goals.• It will provide the crucial link between the photospheric and chromospheric

magnetic field and plasma characteristics obtained by the SUVIT and the high temporal and spatial resolution images of the corona provided by the XIT.

• Key science requirements– Simultaneous spectroscopic measurements in emission lines sampling all

temperature regions present in the solar atmosphere, i.e., Chromosphere – TR – Corona - Flare

– Resolving 0.3” spatial scale to validate the structure connections among all temperature regions

– Effective area an order of magnitude higher than currently available for solar studies, much improving temporal cadence.

• As major European contribution to Solar-C, this telescope with naming LEMUR (Large European Module for Solar Ultraviolet Research) has been proposed to ESA as a mission of opportunity in the 2010 Cosmic Vision Call.

2012.8.13 SCSDM-4 2

SCSDM-4 3

EUVST(LEMUR): instrument requirements

& layout

Slit assembly

2012.8.13

• Optics: single off-axis mirror (30cmf=360cm) and a grating

• Telescope length: 430cm

With low scattering optics, for exploring low EM regions (MR and CH).

EUVST/LEMURItem DescriptionTelescope Off-axis single mirror telescope: diameter of primary: 30 cm

Focal Plane Instruments Spectrographs, Slit imaging camera for co-alignment

Wavelength coverage Spectrographs: First order: 17–21 nm, 69 – 85 nm, 92.5 – 108.5 nm, 111.5–127.5 nm Second order: 46–54 nm, 56–64 nm Slit imaging camera: A chromospheric line/band (e.g., continuum around 160 nm)

Temperature coverage 0.01 – 20 MK

Imaging performance 0.28″ in 80% encircled energy over nominal field of view (FOV) (0.14″ reachable in the 17-21 range on a reduced FOV)

Spatial sampling 0.14” at detector

Slit 0.14″, 0.28″, 0.56″, 1″, 5″

Spectral resolution ( 17,000~30,000

Exposure time 1 – 5 s for 0.28 arcsec sampling 0.1 – 0.5 s for 1 arcsec sampling

Field of view 280 arcsec (along slit) × 300 arcsec (scanning direction)

2012.8.13 4SCSDM-4

Temperature coverage and radiometric performances

5

• Broad temperature coverage 104 K to 107 K• Performance at two temperature regions important for coronal heating studies

Flare lines: Fe XVIII 974 Fe XIX 592 Fe XX 721 Fe XXI 786 Fe XXIII 1079 Fe XXIV 192

2012.8.13 SCSDM-4

For active region plasma

Cou

nts/

s/ar

csec

NeVIII FeiX Mg X FeXI FeXII

FeXVIIIOIV NV, OV

SiIII CIII

SiII HI

IRIS

oo

o

oo

oo

OVI

SCSDM-42012.8.13

• For observing nanoflares, it is important to probe 5-10 MK plasmas with good temperature discrimination. • It is confirmed that the Fe XVIII 974.86 line (log Te~6.80) is strong and unblended. It will allows ~1s

cadence observations of line radiances, profiles, and Doppler flows in hot (6 MK) plasma.• Ca XIV, XV, XVI, XVII lines (log Te =6.55-6.75) are available, but need

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Temperature coverage 1) High temp Corona

Radiometric performance after the revision (2012/1)

SUMER campaign on 8 Nov 2011

(Teriaca et al. 2012)

longer exposures.• Flare lines are

available.

AR (log T/K < 6.2) - 1s exposureAR (log T/K > 6.2) - 1s exposure

log (T/[K])4 5 6 7

FeIX

FeX/XI

MgX

FeXII

FeXIII

FeXIV

SiXII CaXIV

CaXV

CaXVI

CaXVII

FeXVIII

FeXIX

FeXIX

FeXIX

FeXX

FeXXIII

FeXXIIFeXXIV

FeXXI

SCSDM-42012.8.13

Temperature coverage 2) High TR to Corona

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• To properly follow mass and energy flows in the temperature region from high TR to corona, where morphological changes are observed, a further line is needed between the strong OVI 1032 (log Te=5.50) and Ne VIII 770 (log Te=5.75), especially in active region studies.• Having the Ne VII 465 line (log Te= 5.75) becomes possible with modification of instrument design (larger detectors).

SUMER – AR, nearly simultaneous

OVI 1032 NeVIII 770

Intensity

Doppler velocity

AR (log T/K < 6.2) - 1s exposureAR (log T/K > 6.2) - 1s exposure

log (T/[K])4 5 6 7

NeVII

OVI

OV

NeVIII

FeIX

FeX

MgX

OIV

Radiometric performance after the revision (2012/1)

Determine structures and evaluate energy and mass flows from observations

• Trace changes on Poynting flux as a function of space (along B & across B) and time, by observing changes on velocities (Doppler & turbulent) and density (Intensity).

– It is important to identify signatures of energy dissipation, such as temporal and/or spatial damping of waves

2012.8.13 SCSDM-4 8

• Determine “dynamical” structures and their connections in ch.-TR-corona system.

• For oscillations, frequencies, phase speeds and temporal/spatial variation of transverse displacements are measurable. Compare the properties and theoretically modeled wave modes for inferring wave mode.

SCSDM-4 92012.8.13

• SOT imaging obs. tells 0.3~0.4” as typical width of chromospheric spicules.

• Spectroscopic measurements with EIS suggests only ~10% of volume in coronal loops (~0.3” in length) is filled with hot plasma.

CaIIH spicules on the limb

DiskCenter (C)

Limb (L)

White lines: Magnetic field lines

• Unresolved high-speed (>100km/s) jets at base of coronal loops

• Unresolved dynamic events and structures

Corona (~1”)Chromosphere (~0.3”)

Chr.(CaII) 3-5min, TR(Si IV) in bursts of up to 30 min, Corona(NeVIII) more diffuse

Resolving 0.3” spatial scale essential to trace structure connections in atmospheres

High cadence to follow physical changes

• “Fast” scan observations– Effective area an order of magnitude

higher than currently available instruments

2012.8.13 SCSDM-4 10

(DePontieu et al.2007)Repeated scan for 5”

Hinode/SOT Spicles

Observation mode examples

slit width 1” 5s (AR) – 15s (QS) for 5” width 0.28” 18s (AR) - 54s (QS) for 5” width if 1s for AR and 3 s for QS is used as exposure.

Powerful to measure properties of oscillating structures (waves).

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EUV/UV High-throughput Spectroscopic Telescope

Slit assembly

2012.8.13

• One of key instruments for archiving Solar-C science goals

With low scattering optics, for exploring low EM regions (MR and CH).

2012.8.13 SCSDM-4 12

EUVST/LEMURItem Science

requirementsScience backgrounds

Related hardware limitations

Telescope aperture 30 – 40 cm High sensitivity Primary mirror acts as a scanning mirror as well.

Wavelength (or line) selection

Spectrometer: Fist order: 17–21 nm, 69 – 81 nm 96 – 109 nm, 115–127 nmSecond order: 48–54 nm, 58–64 nm Slit jaw imager:Band candidates: H I Ly-alpha 122 nm, Mg II 280 nm, Ca II 393 nm

Spectrometer: Coverage of chromosphere (104K) to corona (107 K in flare) by strong emission lines in EUV and VUV wavelength bandSlit jaw imager:Alignment with imaging data of other instruments

Spectrometer: Visible-light sensitive detector for 17-21nm band, visible-light blind for others

Spectral resolution λ/Δλ ~30,000 - Enhancement in velocity resolution for the unresolved velocity signature at the energy deposition site in Hinode observations

- Instrument length < spacecraft- Minimum number of reflection

Spatial resolution 0.28” (0.14” sampling) Coronal volume filling factor ~0.1 from Hinode observations of 2” spatial resolution

- Instrument length- Magnification of the concave

grating- Pointing control by instrument

Exposure cadence - 1 – 5 sec for 0.28” sampling- < 1sec for 1” sampling

- Rapid heating of coronal structures

- Effective area (Size of primary mirror, reflectance, grating efficiency, detector efficiency)

Cadence of raster scan obs. ~20s for 20” wide area ~200s for 200”wide area

- Local dynamics - Dynamics in active regions

- Readout speed of detector- Response time of mechanisms

Field of view Spectrometer:280” (along slit) ×300” (scan range)Slit jaw imager: > 300” ×200”

Full coverage of an active region

Alignment with imaging data of other instruments

- 2K pixel detector along the slit- Scanning range