Model Instruments Baseline Specification and Key Open Issues – X-ray Imaging Telescope (XIT) – Taro Sakao (ISAS/JAXA) 1Solar-C St Andrews2012/8/13

Imaging Observation of the Corona Phenomenological “connectivity” between the base of the corona and the chromosphere/transition region with EUV-line images Heating and activities of hot loops with broad-band soft X-ray images TRACE 171ÅEIS 195Å EIS 284ÅSXR (XRT) 2Solar-C St Andrews “What corona do we want to see?” 2012/8/13

Introduction X-ray Imaging (Spectroscopic) Telescope for Solar-C – Solar-C: Perform seamless observations of the solar atmosphere (photosphere, chromosphere, transition region and corona) with a suite of 3 telescopes. – Expected contributions from imaging observations of the corona Reveal forms and mechanisms of (storage and) dissipation of energy Quantitative understanding on the reconnection physics Connectivity with the lower atmosphere Two possibilities under study for the X-ray telescope – (1) Ultra-high-resolution normal incidence EUV telescope  Context information for LEMUR – (2) Photon-counting imaging-spectroscopic grazing incidence X-ray telescope 3Solar-C St Andrews2012/8/13

Current Concept of X/EUV Telescope for Solar-C A Pair of NI and GI Channels Normal Incidence – Ultra-high-resolution with high-cadence imagery in EUV wavebands Connectivity with lower atmosphere Context information for EUVST – ” angular resolution (0.1”/pixel) with cadence <10 s for AR/FL – 171, 94 and 304 (or 1548 UV) Å bands Grazing Incidence – Highest spatial-resolution soft X-ray imaging-spectroscopy Provide physical context (entire loop info.) for NI observations with its wide temperature coverage Photon-counting capability for reconnection structure etc. – ~< 1” angular resolution ( ”/pixel) – 0.9 o (~<2 keV) and 0.45 o (~ keV) grazing angles Photon-counting with 0.45 o 4Solar-C St Andrews2012/8/13

Preliminary Illustration of Solar-C X/EUV Telescope “Everything in a package” 3 NI Channels: 94, 171, 304 Å (or 1548 Å) 2 GI Channels: 0.9 deg & 0.45 deg graz. angles * 0.45 deg  Photon Counting 5Solar-C St Andrews (Figure courtesy of SAO) 2012/8/13

Ultra-High-Resolution EUV Telescope Solar-C St Andrews62012/8/13

Correspondence of low corona and chromosphere at ultra-fine scales Ji, Cao, and Goode 2012, ApJ - BBSO/NST He I 10830Å - SDO/AIA 171 Å Structure with diameter ~100 km AIA 193Å NST He I Å 7Solar-C St Andrews2012/8/13

Solar-C St Andrews8

Preliminary Features of Ultra-High- Resolution EUV Telescope ItemEUV TelescopeEUVS/LEMUR Telescope32cmφ primary mirror 3 sector coating (Ritchey-Chretien; ~4 m length) Tip-tilt control of the secondary Wavelength channel Temperature coverage 171 Å, 94 Å, and 304 Å or UV band (0.8MK / 1MK & 8MK(FL) / 0.05 MK) [some from 94/171/195/211/304/335Å] Spatial resolution0.2” – 0.3” (0.1” pixel)0.16” pixel Exposure cadence Exposure time ： AR (<3 MK) – 1 s, FL – 0.1 s Cadence ： < 10 s (for AR <3 MK) Exposure time ： AR – 1-5 s (w/ 0.33” spatial sampling) Field of view~400” x 400”200” nominal > 300” extended 9Solar-C St Andrews2012/8/13 Provide context for EUVST Image - Lower TR - Lower corona - Hot corona (with 1 MK)

NI Line Selection Science with NI telescope(s) largely depends on which wavelength bands are to be employed. In addition to 171 Å band: Will there be 304 Å (He II) band?  Yes (or UV-band?) Imaging of spicules and prominences can be made at spatial resolution similar to SOT-FG. (Joint observation with SUVIT.) Will there be science output beyond SOT-FG? – Temperature difference between 0.1 MK (lower TR with NI) and 0.02 MK (upper choromosphere with SOT) would be important? – Will there be wavelength bands with >5 MK contribution (94 Å and/or 335 Å) besides 1-2 MK bands?  Yes, 94 Å High-temperature bands would be useful in identifying heating sites. The current baseline NI bands (171, 304, 94 Å) are more oriented to take narrow-temperature-band (“single- temperature”) images, overlapping with EUVST temperatures. [171 (5.9), 304 (4.7), 94 (blend of 6.0 & 6.9 for flares)] 10

Grazing-Incidence X-ray Telescope with Photon-Counting Capability Solar-C St Andrews112012/8/13

Science Targets of the GI Telescope (Photon-Counting) Energy dissipation processes in the corona that lead to dynamic activities of the corona. MHD structures assoc. with magnetic reconnection during flares – Identify, e.g., shock structures (slow shock, fast shock) Plasma conditions (temperature, heating status) in the upstream/downstream regions of a shock – Electron temperatures from continuum spectra – Spatial distribution and evolution of supra-thermal electrons (which serve as the seed for accelerated electrons) Heating mechanism for active regions – In particular, for hot plasmas in the AR core: Spatial and temporal evolution of spectra with high time resolution by virtue of non-dispersive imaging-spectroscopy * Particularly powerful under the nano-flare-heating picture for ARs. – Spatial distribution of spectral features (Disk AR ・・ lateral, Limb AR ・・・ vertical ） 2012/8/1312Solar-C St Andrews

(Tsuneta, Ap. J. 1997) Possibilities: Shocks in the Reconnection Structure (Tsuneta, Ap. J. 1996) 13Solar-C St Andrews2012/8/13

(Tsuneta, Ap. J. 1997) Possibilities: Shocks in the Reconnection Structure (Tsuneta, Ap. J. 1996) e - distribution spectra outside diffusion region e - distribution spectra around reconnection point Imada et al. JGR 2011 Electron acceleration at Earth’s magnetotail 10 keV Supra-thermal electrons Thermal electrons Energy range covering up to ~10 keV should clearly identify presence of supra-thermal electron components 14Solar-C St Andrews2012/8/13

Expected Observation Target Regarding Reconnection Physics 2012/8/13Solar-C St Andrews15 (Tsuneta et al. 1997) 1% of Peak EM 20% of Peak EM (Aschwanden et al. 1996) Typ. Electron TOF distance ~ 1.43 x Loop half-length  Not much far from SXR loop main body May be able to perform proper photon-counting imagery around e - start point!

Expected AR Count Spectra ~15 s Integration for 1.2”-square Area Red: with 10MK component Black: without 10MK compo. (Attenuation filter: Be 2  m) 0.55 Fe lines sensitive to LogT=7 2 1% of 1-3 MK plasmas assumed 2012/8/1316Solar-C St Andrews

XRT Filter-Ratio Temperatures (Narukage et al. 2011) Ti/Poly – Al/Mesh Pair Med-Be – Thin-Be Pair (Texp = 20s / 4.3s) (Texp = 2.1s / 0.9s) Red: AR with 10MK component Black: AR without 10MK compo. No significant difference between with and without 10 MK component. 2012/8/1317Solar-C St Andrews

Key Features of the Photon-Counting Soft X-ray Telescope ItemDescription OpticsWolter I segment mirror (1/3 of entire circle), Ir-coated Grazing incidence angle: 0.45 deg Focal length: 4 m Plate scale: 0.4”-0.5”/pixel Focal-Plane Detector CMOS-APS. 2k x 2k  m pixel size Frame read-out rate: 1000 fps Energy resolution equivalent to CCD (Si detector) Energy range~0.5 – 10 keV Photon-counting areaBaseline: ~80” x 400” Goal: ~200” x 400” (cover NS x EW extent of ARs) [Photon integration: ~400” x 400”] Ang. res. & temporal res. for imaging spectroscopy Energy spectrum in each 1”-2” square area for every s.... Even faster for line imaging. Telescope envelope~40 cm x 40 cm x 4.5 m 18Solar-C St Andrews2012/8/13

FL (M2)ARQSCH  = 0.45° Electron rate (e - /s/pxl)1.2 x x x x 10 1 Exp. Time (s) *1 2.5 x ms1.1 s1.1 x 10 2 s6.0 x 10 2 s  = 0.9° Electron rate (e - /s/pxl)5.6 x x x x 10 2 Exp. Time (s) *1 5.4 x ms2.2 x s2.1 x 10 1 s1.1 x 10 2 s XRT (FW = Open-Open) Electron rate (e - /s/pxl *2 )8.2 x x x x 10 2 Exp. Time (s) *1 3.6 x ms1.7 x s1.4 x 10 1 s7.5 x 10 1 s *1: Time for accumulating 30 ke -. *2: GI telescope pixel size set to be 0.4” while XRT 1”. Exposure Times with Photon Integration Mode For  = 0.45° : Single mirror piece of 120 o opening angle, 8 cm paraboloid section For  = 0.9° : Single mirror piece of 68 o opening angle, 20 cm paraboloid section For  =0.45 o, good T exp for FL & AR while less performance for QS & CH, for full-res. imaging. For  =0.9 o, comparable T exp to XRT expected for all targets, even with full-res. imaging. 19Solar-C St Andrews2012/8/13

Issues (Personal View) If we can have both NI and GI as a telescope suite, it would be great. However, if it turns out not realistic, what would be the choice? NI scientific weaknesses – What is its own science? Little spectroscopic info. available Can sparse wavelength bands helpful? Can it be beyond a context imager? – Probably miss many temperature components in the corona such as AR core. Overall loop geometry not visible. GI scientific weaknesses – Base of the corona not well addressed Limited angular resolution (~1” vs ”) – Insufficient imagery performance particularly for QS and CH with the photon-counting GI. Question: What Solar-C can do for QS & CH ? Who is to do? 20Solar-C St Andrews2012/8/13

Backup Slides Solar-C St Andrews212012/8/13

XIT/GI ItemDescription Telescope Ritchey-Chretien telescope: diameter of aperture: ~30 cm Focal plane detector Back-illuminated CCD Wavelength range 9 – 34 nm (some from 9.4nm, 17.1nm, 19.5nm, 21.1nm, 30.4 nm, 33.5nm) Plate scale 0.1 arcsec/pixel sampling Spatial resolution 0.2 – 0.3 arcsec within 200 arcsec off-axis distance Exposure cadence < 10 sec Filed of view 400 arcsec × 400 arcsec ItemDescription Telescope Wolter-I telescope: diameter of aperture: ~25 cm Focal plane detector Back-illuminated CMOS-APS Energy range 0.5 – ~10 keV Energy resolution ~150 eV at 5.9 keV Plate scale 0.5 arcsec sampling Spatial resolution 1.0 arcsec within 200” off-axis distance Exposure cadence Photon integration mode: < 1 sec Photon counting mode: 10 (20) sec for 2” (1”) area Filed of view Photon integration mode: 400 arcsec × 400 arcsec Photon counting mode: ~80 arcsec × 400 arcsec (baseline) ~200 arcsec × 400 arcsec (goal; cover NS×EW extent of ARs) XIT/NI 22Solar-C St Andrews2012/8/13

XIT(GI, NI) ItemScience requirementsScience backgrounds Related hardware limitations Wavelength selection GI: soft X-rays 0.5 – 5 keV (baseline) 0.5 – 10 keV (goal) NI: some from 6 EUV bands GI: revealing the site of heating in the corona NI: image low corona as well as flare high temperature plasmas GI: photon-counting possible in soft X-rays NI: contribution of many other lines Wavelength resolution λ/Δλ GI: ΔE ~ 150 eV NI: λ/Δλ > 30 GI: obtain emission-line structure in energy spectrum NI: avoid confusion due to nearby emission lines GI: available energy resolution of Si NI: resolution of multi-layers < 40 Spatial resolution GI: 1.0” (0.5” sampling) NI: 0.2” (0.1” sampling) GI: ~1/3 scale size of known flare structures near reconnection site NI: coronal volume filling factor ~0.1 from Hinode observations of 2” spatial resolution GI: telescope length < spacecraft NI: trade between spatial resolution and wide field coverage Field of view GI: -integration mode: 400×400 arcsec -ph-counting mode: 80×400 arcsec NI: 400×400 arcsec GI & NI: Full coverage of an active region GI: - APS detector format of 2K×2K and spatial sampling - on-board ph-counting speed NI: CCD format of 4K×4K and spatial sampling Exposure cadence GI: ph-integration mode < 1 sec ph-counting mode 10 (20) sec for 2” (1”) area NI: < 10 sec GI: rapid heating of coronal structures NI: Faster cadence than LEMUR for providing context images GI: - Effective area NI: readout speed of 4K×4K (can be improved by CMOS) telemetry amount 23Solar-C St Andrews2012/8/13

Fig Imagery cadence ~<10 s for 171 and 304 Å 24Solar-C St Andrews2012/8/13

Three-Channel NI Layout Primary: Φ32 cm, efl=16 m Sector: A geom ≈ 100, 200, 300 cm 2 Channel selection via focal plane filters! 171Å UV or 304Å 94Å 25Solar-C St Andrews (Figure courtesy of SAO) 2012/8/13

Key Features of the Photon-Counting Soft X-ray Telescope ItemDescription OpticsWolter I segment mirror (1/3 of entire circle), Ir-coated Grazing incidence angle: 0.45 deg Focal length: 4 m Plate scale: 0.4”-0.5”/pixel Focal-Plane Detector CMOS-APS. 2k x 2k  m pixel size Frame read-out rate: 1000 fps,  RON ~ 5 e - rms Energy resolution equivalent to CCD (Si detector) Energy range~0.5 – 10 keV Photon-counting areamin.: 100 x 100 pixels goal: 512x512 pixels out of the 2k x 2k array Ang. res. & temporal res. for imaging spectroscopy Energy spectrum in each 1”-2” square area for every s.... Even faster for line imaging. Telescope envelope~40 cm x 40 cm x 4.5 m Photon counting ROI: > 80” x 400” Photon counting ROI: > 200” x 400” 26Solar-C St Andrews2012/8/13

GI Mirror Effective Area GI#2 (0.9°) GI #1 (0.45°) XRT(0.9°) GI #1 (0.45°) Similar Aeff as XRT even for <2 keV Larger Aeff than GI #1 (0.9°) for >~5 keV Photon Counting observation GI #2 (0.9°=XRT) Exp. time per pixel consistent with XRT by use of a large mirror 27Solar-C St Andrews2012/8/13

Summary ItmsPhoton-Counting X-ray TelescopeUltra-high-resolution EUV Telescope Angular resolutionModerateGood Temperature coverageHigh T OK, Not suited for low T T complementary to EUVST Low T OK, High T limited within EUVST range Temporal resolutionModerate - Low?Maybe OK? (Good for EUVST) * But matches with ang. res.? Spectroscopic capabilityYesNo, unless multiple channels equipped Scientific strengthCover all coronal T incl. flares jointly with EUVST Spectroscopy on high T plasmas Provide good context info. for EUVST to jointly investigate small-scale dynamics Technology maturenessNot high, but technology growing rapidly Maybe high (AIA etc. heritage) NI & GI under consideration for coronal imager 28Solar-C St Andrews2012/8/13