X-ray emission shape/size analysis at LLE F. J. Marshall, LLE

Transcription

1 NISP Workshop March 2016 X-ray emission shape/size analysis at LLE F. J. Marshall, LLE Outline of talk: Instruments used to image cryogenic target implosion cores: Time integrated: GMXI, KB3 Time resolved: KBFRAMED, SFC3 w/pinhole array Method of determining core size Comparison of sizes from different directions: Time integrated: GMXI, KB3, KBFRAMED(unframed mode) Time resolved: KBFRAMED, SFC3 Direct comparison of core size along common perpendicular lines of sight:

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6 KBFRAMED has a known response to soft x rays KBFRAMED (unframed) has the following sensitivity: f = s(e) * ε KB (E) * Ω / M 2 where f is the flux density at the image plane in kev/kev/cm 2 /s and s = surface flux density in kev/kev/cm 2 /s/sr ε KB = KB microscope efficiency (reflectivity * filter transmission) Ω = solid angle of the microscope M = magnification. For KBFRAMED: Ω = 9 x 10-8 sr M = 12.0 The counts seen in a particular image are given by: C = de * s(e) * ε KB (E) * Ω / M 2 where ε KB is the reflection efficiency times the filter transmission.

7 KBFRAMED (unframed response) Ir reflectivity with 1 mil Be filter (6.5 mils Be total) Efficiency +1 mil Al +2 mils Al Energy (kev) Note: Blast shield = 4 mils Be, vacuum Be window = 1 mil Be secondary debris shield = 0.5 mils Be (total filtration = 5.5 mils Be + filter at image plane, 6.5 mils Be in example above)

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9 The GMXI has a resolution of ~8 µm at best focus when images are recorded by CID cameras Backlit 500 mesh Cu grid image corrected to target plane OMEGA shot µm 8 µm Signal (kadus) 8 um fwhm gaussian Magnification: ave horizontal vertical verified to better than 1% Position (microns) F. J. Marshall and J. A. Oertel, Rev. Sci. Instrum. 68 (1), January 1997

10 Image-to-image timing is precisely determined from position and the use of measured cables (±2 ps).

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12 (SFC3 PSF 12 µm)

13 03/04/2016 OMEGA shot 77064: KBF image 7 PSF smoothed image Super-Gaussian Fit Image-Fit Lineout indicated by dotted line Inferred fit Ro (microns): maximum: exponent: a/b: phi (deg): background: / / / / / / mils Be, 2 mils Al 200. by 200. micron region psf(fwhm) = 6.0 microns Output of aq_gaussfit1.pro kadus Image, Fit(dots), Inferred(red) Position (microns) R 17 =21.4±0.3

14 05/06/2015 OMEGA shot 77064: SFC3T5, IMAGE 35 PSF smoothed image Super-Gaussian Fit Image-Fit Lineout indicated by dotted line Inferred fit Ro (microns): maximum: exponent: a/b: phi (deg): background: / / / / / / mils Be, 1.5 mils Al 200 by 200 micron region psf(fwhm) = 12.0 microns Output of aq_gaussfit1.pro intensity(a.u.) Image, Fit(dots), Inferred(red) Position (microns) R 17 =22.1±0.3

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18 The cryogenic target implosion cores have been measured with two KB microscopes in time integrated mode 50.0 KB3c vs GMXIc image sizes on cryo shots KB3C R17%(corr) KB3C vs GMXIC x = y Linear (KB3C vs GMXIC) y = 1.027x GMXIC R17%(corr) The two measurements infer a core size that agree within a few percent of each other from quasi-orthogonal views

19 Cryogenic target implosion cores have been measured with KBFRAMED, a framed pinhole array, and a time integrated KB z V SFC3 x V KB3 V GMXI y The larger time integrated core sizes place an upper limit on emission-region-size evolution of ~ 5 µm

20 The flux along common perpendicular lines of sight can be compared exactly by rotation and integration V z v ab In coordinates of image: va vb =, where vab is the common axis v v a b z vi v i q i vab p i q i =, pi =, αi = arctan, i= ab, z vi v i qi vab q i Flux along common line of sight: ( ) F p ' = f ( q ', p ' ) dq ', where v = q' = q' i i i i i ab a b v ab Assuming omnidirectional, optically-thin emission ( ' ) = ( ' ) F p F p a a b b x V KB3 V GMXI y

21 OMEGA cryogenic target shot Rotated to common perpendicular view p' 88.9 KB3 d image 100 µm p' GMXI d image V V Rotated images are summed in vertical direction to compare core shape V KB3 V GMXI

22 OMEGA cryogenic target shot Summations along common perpendicular lines of sight KB3 d GMXI d-image Normalized signal GMXI d KB3 d-image Distance (microns)

23 OMEGA cryogenic target shot Summations along common perpendicular lines of sight KBF 5 GMXI c image Normalized signal GMXI c KBFRAMED (unframed) Image 5 Distance (microns) Flux at image plane (KBF) was ~4000 photons/res el at peak of image from calibrated Biomax response assuming 5 kev

24 NISP Workshop March 2016 CONCLUSIONS X-ray emission shape/size analysis at LLE F. J. Marshall, LLE The size and shape of the cryogenic target implosion cores are being measured by multiple x-ray imaging diagnostics on OMEGA Simultaneous time-integrated images shown agreement within ~3% on average with large directional deviations on individual shots Time-resolved images at the peak of the stagnation agree closely as to the size of the core (within ~5%) Comparison of images along mutually perpendicular lines-of-sight confirm that only directional differences affect the measurements

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27 F. J. Marshall, et al., POP vol.4, 1118 (1998). with LANL framing camera