6/2/2015 Solar-B XRT XRT-1 A High Resolution Grazing Incidence Telescope for the Solar-B Observatory...

04/18/23 Solar-B XRT XRT-1

A High Resolution Grazing Incidence Telescope for the Solar-B Observatory

Solar-B XRT

Presenter: Leon GolubSmithsonian Astrophysical Observatory


XRT Team

U-Side• Leon Golub U.S.-P.I.• Jay Bookbinder P.M.• Peter Cheimets P.E.• Ed DeLuca P.S.• Alana Sette• Mark Weber

J-Side• Kiyoto Shibasaki P.I.• Taro Sakao Secretariat • Ryouhei Kano Secretariat

… and many others in US and Japan.


Talk Overview

• The Solar B Mission

• The X-Ray Telescope on Solar B– Science Requirements– Instrument Design

• Sample Observing Plans– XRT “firsts”


Solar B Spacecraft

• Mass: 875 kg

• Power: 1000W

• Telemetry: 4Mbps

• Data Recorder: 8Gbit

• Attitude: Solar pointed

• Stability: 0.3 arcsec per 1s

• Launch: Summer 2006

• Orbit: Polar, Sun-Sync, 600km


Solar-B XRT Flight Design

Front Door and Hinge Assembly

Electrical Box

Ascent Vents2 places

Graphite Tube Assembly

CCD Cameraand Radiator


XRT Instrumentation

• X-Ray Telescope– Mirror inner diameter: 35 cm

– Focal Length 2700 cm

– Geometric Area 5 cm2

• Shutter/Analysis Filters– τexp 1ms to 10s

– 9 X-ray, 1 WL filter

• Camera– 2Kx2K back-illuminated CCD

– 1 arcsec pixels (13.5μm)


Focal Plane Filter Wheels

Open

ThinBe

Ti/Poly

ThickAl

ThickBe

MedBe

Open

Med Al

WhiteLight

Al/Poly

Al/Mesh

C/Poly


XRT Exposure Times

Flare (Dere & Cook '79 M2)

Ph/s/pix FW/s/pix Max. Exp. Time (ms)

Thick Al 2.70E+05 570 1.8Medium Be 1.10E+06 2600 0.4

Thick Be 6.70E+04 300 3.3

Active Region Ph/s/pix FW/s/pix Max. Exp. Time Thin Al Mesh 23800 27 0.04 Al Polyimide 20000 29 0.03

Al/Ti Polyimide 15400 26 0.04 C Polyimide 13800 21 0.05 Ti Polyimide 10764 16 0.06

Thin Be 8280 14 0.07Thick Al 557 1 1.00

Medium Be 2330 4.6 0.22Thick Be 47 0.2 5.00

Focal Plane Intensities for XRT Passbands


XRT Science Goals

1. Coronal Mass Ejections

2. Coronal Heating

3. Reconnection and Jets

4. Flare Energetics

5. Photospheric-Coronal Coupling


XRT Science Goals 1

• Coronal Mass Ejections– How are they triggered?

• High time resolution– What is their relation to the magnetic structures?

• High spatial resolution– What is the relation between large scale instabilities

and the dynamics of small structures?• Large FOV• Broad temperature coverage


CME Movie


XRT Science Goals 2

• Coronal Heating– How do coronal structures brighten?

• High time resolution– What are the wave contributions?

• High Spatial Resolution– Do loop-loop interactions cause heating?

• Large FOV• Broad temperature coverage


Coronal Heating: Sample Observation

What needs to be explained:• Outflows• Motions along field• Separatrices and QSLs• Intermingled hot and cool plasma


XRT Science Goals 3

• Reconnection and Jets– Where and how does reconnection occur? Is it related to

slow CMEs?• High time resolution• Large FOV

– What are the relations to the local magnetic field?• High spatial resolution• Broad temperature coverage• Coordinated observing with EIS/SOT


Slow CME-associated Flare Events


XRT Science Goals 4

• Flare Energetics– Where and how do flares occur?

• High time resolution– What are the relations to the local magnetic field?

• High spatial resolution• Large FOV• Broad temperature coverage• High temperature response• Large dynamic range


Flare Energetics - Example


SXT Science Goals 5

• Photospheric-Coronal Coupling– Can a direct connection between coronal and

photospheric events be established?

• High time resolution

• High spatial resolution

– How is energy transferred to the corona ?

• Large FOV

– Does the photosphere determine coronal fine structure?

• Broad temperature coverage

• Coordinated observing with SOT-FPP/EIS


Example: Rotating Spot

The time has come to move beyond “loops”and “isolated mini-atmospheres”!

Courtesy A. Title


The XRT “Firsts”

1. Unprecedented combination of spatial resolution, field of view and image cadence.

2. Broadest temperature coverage of any coronal imager to date.

3. High data rate for observing rapid changes in topology and temperature structure.

4. Extremely large dynamic range to detect entire corona, from coronal holes to X-flares.

5. Flare buffer, large onboard storage and high downlink rate provide unique observing capability.

New XRT Instrumental Capabilities:


Anticipated XRT Science “Firsts”

• Flares & Coronal Mass Ejections. • How are they triggered, and what is their relation to the numerous small

eruptions of active region loops? • What is the relationship between large-scale instabilities and the dynamics of

the small-scale magnetic field?• XRT will determine the topology, physical parameters (T, ne) and

interrelatedness of the regions integral to flare/CME formation.

• Coronal heating mechanisms. • How do coronal loops brighten? TRACE has observed loop oscillations

associated with flares (Nakariakov et al. 1999). Are other wave motions visible? Are they correlated with heating?

• Do loops heat from their footpoints upward, or from a thin heating thread outward? Do loop-loop interactions contribute to the heating?

• XRT will exhibit the evolution and activity of both active and quiet inner coronal structures on MHD (seconds) to surface B diffusion (days) timescales.


Anticipated XRT Science “Firsts”

• Solar flare energetics. • Solar-B will observe many flare event. The XRT can test the reconnection

hypothesis that has emerged from the Yohkoh data analysis. • XRT will greatly extend the sample of observed flares in intensity, spatial and

temporal resolution, allowing stringent tests of flare theories.• Reconnection & Coronal Dynamics.

• Yohkoh observations of giant arches, jets, kinked and twisted flux tubes, and microflares imply that reconnection plays a significant role in coronal dynamics. With higher spatial resolution and with improved temperature response, the XRT will help clarify the role of reconnection in the corona.

• XRT will determine importance of flows, B-field–plasma interactions, relevance of null points, reconnection sites and separatrix (or QSL) surfaces.

• Photosphere/corona coupling. • Can a direct connection be established between events in the photosphere and a

coronal response? • To what extent is coronal fine structure determined at the photosphere?


Typical XRT Observing Plan

Assumptions:

•X-ray data compress to 3 bits/pixel•White light data compress to 5 bits/pixel•Filter move and settle time 1.2 s per step•Shutter prep time 0.2 s•Parallel shift @ 10krows/s read time 512kpixels/s• => 3.075 s to read 768x768 FOV• Exposure times: 1s for filters 1 & 2; 3s for filter 3

Data Rate: 53 kB/s Compressed data


Sample XRT Program

Emerging Flux Program

Understand the interaction of emerging magnetic flux into the existing coronal magnetic field.

Implementation: •Follow an AR as it crosses disk center (~1 week)•Use 768x768 FOV (13'x13')•Use 3 filters to obtain basic temperature coverage•Run at a 60-sec. cadence to follow coronal structures•Take WL images every 45 min for context & alignment


Use of On-Board Storage

Typical observing program requires >6 downlinks per day.


End Presentation


Parameter Value Driver Exposure Time 4 msec

3 sec Flare brightness Quiet sun

Cadence 2 sec (reduced FOV)

Flare variability

T-range 6.1 < log T < 7.5 Coronal DEM T-resolution Log T = 0.2 Transverse gradients X-ray image resolution

2 arc-sec (1 arc-sec pixel)

“moss” size scales

FOV >30 arcmin Global Variations White light rejection

>10**11 L_x/L_opt

Instrument Requirements


Analysis Filter Set FILTER

Material Thickness Material Thickness Material (Å) or % Trns. Front Back

Entrance: Al Polyimide Al 1200 Polyimide 2500 Al2O3 75 25

Focal Plane: Thin Al Mesh Al 1600 Mesh 82% Al2O3 75 75 Al Polyimide Al 1600 Polyimide 2500 Al2O3 75 25

C Polyimide C 7000 Polyimide 2500 0 0 Ti Polyimide Ti 3000 Polyimide 2500 TiO2 75 25

Thin Be Be 9um - 100% BeO 75 75

Medium Al Al 12.5um - 100% Al2O3 75 75Medium Be Be 30um - 100% BeO 75 75

Thick Be Be 1mm - 100% BeO 75 75Thick Al Al 25um - 100% Al2O3 75 75

White Light SiO2 2.5mm

Oxide LayersBackingThickness (A)


XRT Exposure Times

Quiet Sun Ph/s/pix Elec/s/pix Min. Exp. Time Thin Al Mesh 107 2400 1 Al Polyimide 17 664 6

Al/Ti Polyimide 12 540 8 C Polyimide 3 276 33 Ti Polyimide 3 262 33

Bright Points Ph/s/pix Elec/s/pix Min. Exp. Time Thin Al Mesh 348 7920 0.3 Al Polyimide 55 2320 2

Al/Ti Polyimide 40 1910 2.5 C Polyimide 11 1010 9 Ti Polyimide 10 935 10

Focal Plane Intensities for XRT Passbands


Diagnostics via Focal Plane Analysis Filters and Filter Ratios

Throughputvs. T for C,Al, and Ti

Filter ratios vs. T for some representativefocal plane filter pairs.


XRT DEM Widget Interface

No. knots isno. bands - 1

Initial guess:Flat (unit) DEM

No errors includedIn this example!


“Real” AR DEM

4 filters 7 filters

Solid line: Input DEM

Dashed lines: Best-fit Model DEMs 100×


Entrance Filter Design

PROTECTIVE COVERATTACHMENT POINTS

CAPTIVE SCREWATTACHMET

FILTER FRAME

BACK SURFACEFRONT SURFACE

LIGHT SUPRESSIONRIB

EN T ER AN C E F ILT ERASSEM BLY

1 01

SLR B-1001

FR AM E, EN T R AN C EFILT ER

1 01

C APT IVE SC R EW ,M 2X .40

1 01


XUV Filter Design

Aluminum-Nickel Mesh Aluminum-Polyimide

Beryllium-Nickel Mesh Titanium-Polyimide


Rear Assembly Overview

FOCUS MECHANISM

FILTER WHEEL ANDSHUTTER ASSEMBLY

CAMERA FOCUS INTERFACE

REAR ADAPTER FLANGE

GRAPHITE TUBE


Artist’s Conception

The Real Thing

Solar-B


Spot Size for Various Focus Positions

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