SolarB XRT

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Solar-B XRT
A High Resolution Grazing Incidence Telescope
for the Solar-B Observatory
Presenter Leon Golub Smithsonian Astrophysical
Observatory
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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.
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Talk Overview

• The Solar B Mission
• The X-Ray Telescope on Solar B
• Science Requirements
• Instrument Design
• Sample Observing Plans
• XRT firsts

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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

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Solar-B XRT Flight Design
Graphite Tube Assembly
Ascent Vents 2 places
CCD Camera and Radiator
Electrical Box

Front Door and Hinge Assembly
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XRT Instrumentation

• X-Ray Telescope
• Mirror inner diameter 35 cm
• Focal Length 2700 cm
• Geometric Area 5 cm2
• Shutter/Analysis Filters
• texp 1ms to 10s
• 9 X-ray, 1 WL filter
• Camera
• 2Kx2K back-illuminated CCD
• 1 arcsec pixels (13.5µm)

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Focal Plane Filter Wheels
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XRT Exposure Times
Focal Plane Intensities for XRT Passbands
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XRT Science Goals

• Coronal Mass Ejections
• Coronal Heating
• Reconnection and Jets
• Flare Energetics
• Photospheric-Coronal Coupling

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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

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CME Movie
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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

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Coronal Heating Sample Observation

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

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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

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Slow CME-associated Flare Events
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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

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Flare Energetics - Example
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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

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Example Rotating Spot
Courtesy A. Title
The time has come to move beyond loops and
isolated mini-atmospheres!
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The XRT Firsts
New XRT Instrumental Capabilities

• Unprecedented combination of spatial resolution,
  field of view and image cadence.
• Broadest temperature coverage of any coronal
  imager to date.
• High data rate for observing rapid changes in
  topology and temperature structure.
• Extremely large dynamic range to detect entire
  corona, from coronal holes to X-flares.
• Flare buffer, large onboard storage and high
  downlink rate provide unique observing capability.

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• 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.

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• 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-fieldplasma 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?

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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 _at_ 10krows/s read time 512kpixels/s
• gt 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

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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

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Use of On-Board Storage
Typical observing program requires gt6 downlinks
per day.
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End Presentation

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Instrument Requirements
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Analysis Filter Set
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Focal Plane Intensities for XRT Passbands
XRT Exposure Times
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Diagnostics via Focal Plane Analysis Filters and
Filter Ratios
Throughput vs. T for C, Al, and Ti
Filter ratios vs. T for some representative focal
plane filter pairs.
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XRT DEM Widget Interface
No. knots is no. bands - 1
Initial guess Flat (unit) DEM
No errors included In this example!
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Real AR DEM
4 filters
7 filters
Solid line Input DEM
Dashed lines Best-fit Model DEMs 100
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Entrance Filter Design
PROTECTIVE COVER ATTACHMENT POINTS
LIGHT SUPRESSION RIB
CAPTIVE SCREW ATTACHMET
FILTER FRAME
FRONT SURFACE
BACK SURFACE
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XUV Filter Design
Aluminum-Nickel Mesh
Aluminum-Polyimide
Beryllium-Nickel Mesh
Titanium-Polyimide
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Rear Assembly Overview
FILTER WHEEL AND SHUTTER ASSEMBLY
GRAPHITE TUBE
CAMERA FOCUS INTERFACE
FOCUS MECHANISM
REAR ADAPTER FLANGE
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Solar-B
Artists Conception
The Real Thing
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Spot Size for Various Focus Positions