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Center for Radiative Shock Hydrodynamics Fall 2011 Review

Center for Radiative Shock Hydrodynamics Fall 2011 Review. Experimental data from CRASH experiments Carolyn Kuranz. CRASH experiments have produced data from shock breakout to 30 ns. Shock Breakout data (~450 ps ) Diagnostics Active Shock Breakout (ASBO) Streaked Optical Pyrometer (SOP)

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Center for Radiative Shock Hydrodynamics Fall 2011 Review

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  1. Center for Radiative Shock HydrodynamicsFall 2011 Review Experimental data from CRASH experiments Carolyn Kuranz

  2. CRASH experiments have produced data from shock breakout to 30 ns • Shock Breakout data (~450 ps) • Diagnostics • Active Shock Breakout (ASBO) • Streaked Optical Pyrometer (SOP) • Early-time data (~2 – 7 ns) • Diagnostic Techniques • Gated imaging x-ray radiography • Streaked x-ray radiography • Late-time data (~13 – 30 ns) • Diagnostic Technique • Ungated x-ray radiography • Preliminary Variations in Geometry • Elliptical Nozzle Tubes • Cylindrical Nozzle Tubes • Wide Cylindrical Tubes Nominal CRASH experiment

  3. ASBO and SOP can detect the shock breakout from a Be disk • Active Shock Breakout (ASBO) uses a probe beam to detect the rate of change in the derivative of the optical path to a surface • A Streaked Optical Pyrometer (SOP) passively detects the thermal emission from a surface

  4. Shock breakout time is observed on both diagnostics ASBO SOP Position Position shock breakout shock breakout Time Time

  5. We have obtained breakout data nominally 20 µm Be disks Systematic error is ± 50 ps

  6. Early-time data is obtained using gated x-ray radiography The detector can use a gated camera or streak camera

  7. Early-time data are obtained using gated x-ray radiography • A V foil and gated 4-strip camera are used • 16 (4x4) pinhole array is in front of the camera • We have obtained data at magnifications of 6 and 8 • Possible to obtain a time sequence and multiple data points • Can be done in 2 views or with streaked radiography • Target design yields highly accurate targets

  8. The strips on the camera can be pulsed at different delays corresponding to a long pulse backlighter (2,2) t = 5.0 ns t = 4.5 ns t = 4.0 ns The shock is at 606 ± 30µm at 4.5 ns t = 3.5 ns

  9. We have obtained data with this technique from ~ 3 - 7 ns

  10. Streaked radiographs provide shock position over several nanoseconds • Streak cameras are time-resolved detectors that convert x-ray signal to an electron pulse • Electrons are accelerated by an electric field and deflected by a voltage ramp • Resulting image is resolved in space and time • Can be done in conjunction with area radiography fiducial wire

  11. We used streaked radiographs to obtain early-time shock position shock front fiducial wire Time Space

  12. Late-time data can be obtained using ungated radiography • A pinhole backlighter is used to create one image onto ungated film • Technique requires large amount of shielding • Can observe target from 2 views • We have used varying tube geometries Tube is inserted in acrylic shield

  13. Ungated x-ray radiographic images of cylindrical tube experiments 13 ns 26 ns Doss, HEDP 2010 We have obtained data with this technique at ~13 ns and ~26 ns

  14. We have performed preliminary experiments to vary tube geometry to prepare for the 5th year experiment To fabricate the unique nozzle targets we utilized 2 methods

  15. All-polyimide tubes were almost good enough • Manufactured at General Atomics and Luxel with parts provided by Michigan • Copper mandrels were dipped in polyimide and rotated while heated • Desired thickness difficult to obtain (measured by interferometry) • However, both vendors learned a lot about the process and can improve it See SR Klein poster

  16. Acrylic nozzles with polyimide tubes is the approach that worked well • Acrylic nozzle is machined and elliptical or cylindrical tube is inserted into acrylic • Elliptical tube is formed by sandwiching between 2 plates and heating • A repeatable method has been achieved and results in within 3% of specification • Fairly easy to make so we make a large batch and choose the best See SR Klein poster

  17. Target tubes were secured with an acrylic cap Narrow view Wide view Acrylic nozzle

  18. Radiographic images from an elliptical nozzle target at 28 ns and 30 ns t = 28 ns t = 30 ns

  19. Radiographic images from a cylindrical nozzle target at 26 ns t = 26 ns t = 26 ns

  20. Radiographic images from a wide cylindrical target at 26 ns t = 26 ns t = 26 ns

  21. Shock positions of different tube geometries

  22. We have obtained a wide range of data with several diagnostic techniques • Differences among shots: • Geometry • Laser energy • Disk Thickness • Xe pressure • Tube material (acrylic/polyimide) Error bars are the size of the markers or smaller

  23. Conclusions and future directions • We have obtained over 100 data points from ~ 35 data shots • Data ranges from shock breakout (~450 ps) to 30 ns and is obtained with several diagnostics techniques • We use a new technique to measure the Be disks that reduces uncertainty in thickness • We have worked with the Omega Laser Facility to reduce timing uncertainty in backlighter pulse timing relative to the drive pulse • We plan to work with General Atomics and Luxel to improve polyimide tubes for Year 5 experiments • This will allow us to observe shock evolution in the nozzle

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