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The Focusing Optics X-ray Solar Imager (FOXSI)

Steven Christe 1 , S. Krucker 2 , L. Glesener 2 , S. Ishikawa 3 , B. Ramsey 4 , T. Takahashi 3 , R.P. Lin 2 1 NASA GSFC, Greenbelt, MD 2 Space Sciences Lab, UCB, Berkeley, CA 3 Dept. of Physics, U. of Tokyo, Japan 4 NASA MSFC, Huntsville, AL. The Focusing Optics X-ray Solar Imager (FOXSI).

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The Focusing Optics X-ray Solar Imager (FOXSI)

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  1. Steven Christe1, S. Krucker2, L. Glesener2, S. Ishikawa3, B. Ramsey4,T. Takahashi3, R.P. Lin2 1 NASA GSFC, Greenbelt, MD 2 Space Sciences Lab, UCB, Berkeley, CA 3 Dept. of Physics, U. of Tokyo, Japan 4 NASA MSFC, Huntsville, AL The Focusing Optics X-ray Solar Imager (FOXSI)

  2. Basic Flare Model • Basic flare model. Upward beams Acceleration site Downward beams Chromospheric evaporation

  3. HXR observations of Flare Model • HXR observations of flare-acceleration electrons • Provide quantitative measurements • Depend on ambient density • Strongest from footpoints • Very faint emission from corona • RHESSI does not have high enough sensitivity or dynamic range • HXR focusing optics can provide it. Upward beams Acceleration site n = 109 cm-3 Downward beams n = 1011 cm-3 SXR Chromospheric evaporation HXR HXR n = 1011-12 cm-3

  4. HXR observations of Flare Model • HXR observations of flare-acceleration electrons • Provide quantitative measurements • Depend on ambient density • Strongest from footpoints • Very faint emission from corona • RHESSI does not have high enough sensitivity or dynamic range • HXR focusing optics can provide it. Upward beams Acceleration site n = 109 cm-3 HXR Downward beams n = 1011 cm-3 SXR Chromospheric evaporation HXR HXR n = 1011-12 cm-3

  5. HXR observations of Flare Model • HXR observations of flare-acceleration electrons • Provide quantitative measurements • Depend on ambient density • Strongest from footpoints • Very faint emission from corona • RHESSI does not have high enough sensitivity or dynamic range • HXR focusing optics can provide both Upward beams Acceleration site n = 109 cm-3 HXR Downward beams n = 1011 cm-3 SXR Chromospheric evaporation HXR HXR n = 1011-12 cm-3

  6. HXR observations of Flare Model • Present day observations show mostly footpoints. Upward beams Acceleration site n = 109 cm-3 RHESSI HXR Obs. Downward beams 60 arcsec n = 1011 cm-3 SXR Chromospheric evaporation HXR HXR n = 1011-12 cm-3

  7. HXR observations of Flare Model • HXR focusing optics provides imaging of the acceleration region • And track electrons in the corona. Upward beams n = 109 cm-3 Acceleration site Downward beams n = 1011 cm-3 SXR Chromospheric evaporation HXR HXR n = 1011-12 cm-3

  8. HXRs from up and down beams • ratio of footpoint to coronal emission depends on: • coronal density • electron spectrum • photon energy • trapping time • but it is generally large Acceleration site Dynamic range: ~400 HXR Flux Height above the photosphere [arcsec]

  9. HXRs from up and down beams • ratio of footpoint to coronal emission depends on: • coronal density • electron spectrum • photon energy • trapping time • but it is generally large Acceleration site Dynamic range: ~400 HXR Flux emission from acc. region? trapping? ? Height above the photosphere [arcsec]

  10. Optics Performance • Current Tech: slumped glass optics, replicated metal optics • Best resolution currently available by B. Ramsey (NASA MSFC) • Individual shell resolution: 7 arcsec (FWHM) • Telescope module resolution: 10-12 arcsec • Dynamic range: 30 arcsec: ~100 50 arcsec: ~500 Point Spread Function (PSF) 0 FWHM 10’’ Metal optics HPD 25’’ -1 -2 Log(relative flux) -3 -4 -5 -100 -50 0 50 100 150 arcsec

  11. Basic Flare Model • Dynamic range will allow us to image coronal HXR emission in the presence of HXR footpoints • Footpoints will be unresolved, but can be separated for larger flares Upward beams Dynamic Range Acceleration site n = 109 cm-3 Downward beams n = 1011 cm-3 SXR 60 arcsec HXR HXR n = 1011-12 cm-3

  12. HXRs from escaping electrons Dt=1 s 2-4 kg/cm2(e.g. 50 kg of optic = 100-200 cm2) Assuming 100 cm2 Dt=30 s • Assuming 100 cm2

  13. Energetic Electrons Jets CME Active Region Flares Type III radio bursts Quiet Sun network flares (coronal heating) Radio bursts from shocks

  14. Focal Plane Detectors • Position sensitive solid state (Si, CdTe, CZT) • Energy resolution 0.2 to 2 keV (1-100 keV) • Current Technology

  15. FOXSI Mission Concept This mission concept is based on existing technology. Currently FOXSI is a sounding rocket (launch Oct. ‘12). HEROES balloon launch in Sept ’13. The future may bring better spatial resolution, lighter optics, etc. FOXSI will observe electrons as they are being accelerated in the corona, along which field line they travel away from the acceleration site, where they are stopped, and how some electrons escape to be detected as SEPs at Earth.

  16. Fin

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