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) o Diagnostics Active Shock Breakout (ASBO) Streaked Optical Pyrometer (SOP) Early-time data (~2 – 7 ns) o Diagnostic Techniques Gated imaging x-ray radiography Streaked x-ray radiography Late-time data (~13 – 30 ns) o Diagnostic Technique Ungated x-ray radiography o Preliminary Variations in Geometry Elliptical Nozzle Tubes Cylindrical Nozzle Tubes Wide Cylindrical Tubes 2 Nominal CRASH experiment

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 3

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

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

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

Early-time data are obtained using gated x-ray radiography A V foil and gated 4-strip camera are used o 16 (4x4) pinhole array is in front of the camera o 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 7

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

We have obtained data with this technique from ~ ns 9

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 10

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

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

Ungated x-ray radiographic images of cylindrical tube experiments 13 ns26 ns We have obtained data with this technique at ~13 ns and ~26 ns Doss, HEDP

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

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) o However, both vendors learned a lot about the process and can improve it See SR Klein poster 15

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 o A repeatable method has been achieved and results in within 3% of specification o Fairly easy to make so we make a large batch and choose the best See SR Klein poster 16

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

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

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

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

Shock positions of different tube geometries 21

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) 22 Error bars are the size of the markers or smaller

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 o This will allow us to observe shock evolution in the nozzle 23