Measures the fast pulses seen with exploding bridge flyers by PD

Hanks, Roy

Hansen, Don

Hodgin, Ralph

May, Chadd

Strand, Ted

Whitworth, Tony

UNT Digital Library

UCRL-CONF-230794Fabry-Perot / PDV ComparisonRalph hodgin, Chadd May, Roy Hanks, DonHansen, Tony Whitworth, Ted StrandMay 8, 200751st Annual Fuze ConferenceNashville, TN, United StatesMay 22, 2007 through May 24, 2007Disclaimer   This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes.  UNCLASSIFIEDThis work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48UCRL-CONF-230794 UNCLASSIFIEDFabry Perot / PDV Comparison51st Annual FUZE ConferenceMay 24, 2007Ralph Hodgin, Chadd May, Roy Hanks, Don Hansen, Tony WhitworthUNCLASSIFIEDPage 2UNCLASSIFIEDRalph HodginObjective: will PDV measure the fast pulses seen with exploding bridge flyersEach test fired under same conditionsChange probes for Fabry-Perot  &  PDV1-2 shots for each setupParylene & Spun KaptonAll Shots into LiF under vacuum0.3 uF FiresetSix shots with PDVCompare Fabry-Perot  to  PDVUNCLASSIFIEDPage 3UNCLASSIFIEDRalph HodginWhat is a SlapperSubstrateGoldDielectric FlyerExploding Foil (al or cu)BarrelTargetSubstrateBridge MaterialFlyer MaterialBarrel LengthTargetH.E.LIFUNCLASSIFIEDPage 4UNCLASSIFIEDRalph HodginHow do you fire a Slapper?Exploding FoilFlyerBarrelhigh currentV TargetUNCLASSIFIEDPage 5UNCLASSIFIEDRalph HodginGeneral Layout of Two-Beam Fabry-Perot System for Diagnostic Measurements on Slapper Initiatorsm m+1SlitTargetPulsed Nd:YAGFast CavitySlow CavityFast Camera Down to 30ns Sweep WindowUNCLASSIFIEDPage 6UNCLASSIFIEDRalph HodginFabry-Perot in HEAFRoom Size2 Fabry-Perot2 Streak CamerasYag Laser UNCLASSIFIEDPage 7UNCLASSIFIEDRalph HodginPhotonic Doppler Velocimeter (PDV)•Portable system – rack mount•Doppler Velocimetry•Greater than 5 mm/µsec velocity•Limited by bandwidth onlyUNCLASSIFIEDPage 8UNCLASSIFIEDRalph HodginThe Fill-Time of the Fabry-Perot Cavity may Filter Sub-Nanosecond Data – PDV may be a Solution0.000.200.400.600.801.001.201.401.601.800 1 2 3 4Particle velocity  (km/s)Measured wave profileCalculated wave profile•Portable system – rack mount•Doppler Velocimetry•Greater than 5 mm/µsec velocity•Limited by bandwidth onlyExperimental and calculated velocity wave profilesinto LiF for a 50um flight distance.UNCLASSIFIEDPage 9UNCLASSIFIEDRalph HodginWhat is PDV  (Photonic Doppler Velocimeter)High speed detectors measure the difference in frequency, ‘the Beat’, between the original signal and Doppler-shifted return signal.LaserDetectorProbeMovingSurfacePortion ofOriginalSignalDoppler-shifted lightUNCLASSIFIEDPage 10UNCLASSIFIEDRalph HodginPDV  The ‘beat’ frequency is converted to amplitudeExpanded view40G sample digitizer25ps/point1550 nm laser wavelengthTed Strand UNCLASSIFIEDPage 11UNCLASSIFIEDRalph HodginFabry-Perot Measurements Conducted in Vacuum Provide Information on Slapper’s Pulse Duration and Equation of StateWorking in a vacuum eliminatesthe air cushion and the air flashat impact.Fabry-Perot  and  PDV SetupProbe for Fabry or PDVUNCLASSIFIEDPage 12UNCLASSIFIEDRalph HodginKowin Simulation of a 60.0um Parylene-C Flyer into LiF with Strong Shock Shows Stepped-Top as Seen with Fast Fabry-Perot Diagnostic024681012140.1 0.11 0.12 0.13 0.14 0.15Time (us)Pressure (GPa)For thick flyers (>40um) a shock wave builds in flyer materialShock causes a second jump in Up in LiF as shown hereFront Surface Velocity of 68.8um FlyerImpact into LIFUNCLASSIFIEDPage 13UNCLASSIFIEDRalph Hodgin68.6um Parylene - FabryComplex ReturnFront & Rear flyer surface producing separate returnsMultiple Returns are easily seen with fabry perotTransparent materialUNCLASSIFIEDPage 14UNCLASSIFIEDRalph HodginThe 60um Parylene-C Flyer Impact IrregularityTwo pressure pulses were measured with Fast Fabry-Perot SystemOriginally we believed that the flyer may have spalledAfter witnessing this effect in other thick flyers we hypothesize that the second step is the result of a strong shock in the thick flyer…UNCLASSIFIEDPage 15UNCLASSIFIEDRalph Hodgin68.8u Parylene Flyer6ns fft window3ns fft windowRaw Fabry-Perot DataPDV Spectrograph with 3ns windowReanalyzed with a 6ns FFT windowUNCLASSIFIEDPage 16UNCLASSIFIEDRalph HodginComparison for 68.6um Parylene-C FlyerAll PDV shots used a 3.2ns FFT WindowShould try faster window for pressure pulseOne of several methods for data analysisThe ‘step’ on the pressure pulse seen on both Fabry-Perot  and  PDV4ns fidPreliminary PDV/Fabry Comparison00.511.522.533.54-0.05 0 0.05 0.1 0.15 0.2Time (us)Veloicty (mm/us)PDV with 3ns FFT Window Shot 1PDV with 3ns FFT Window Shot 1PDV with 3ns FFT window Shot 2PDV with 3ns FFT Window Shot 2Fabry VelocityFabry UpUNCLASSIFIEDPage 17UNCLASSIFIEDRalph Hodgin50.4u Paralyne Flyer Spectograph & Fabry-PerotUNCLASSIFIEDPage 18UNCLASSIFIEDRalph HodginPDV/Fabry-Perot Comparison 50.4um Parylene-CPDV/Fabry Comparison00.511.522.533.544.50.24 0.26 0.28 0.3 0.32 0.34 0.36 0.38 0.4Time (us)Velocity (mm/us)PDV #1PDV # 1PDV #2PDV #2FabryFabryUNCLASSIFIEDPage 19UNCLASSIFIEDRalph Hodgin12.3u Spun Kapton Flyer1880Thin flyers produce a very narrow pulse on impactUNCLASSIFIEDPage 20UNCLASSIFIEDRalph Hodgin12.3um Flyer Fabry to PDV Comparison ShotPDV 3ns window did see the pulse Same Velocity profile12.3 um Parylene-C Flyer into LiF0123456-0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18Time (us)Velocity (mm/us)FabryFabryPDV #1PDV #1PDV #2PDV #212.3 um Parylene-C Flyer into LiF00.511.522.50.06 0.065 0.07 0.075 0.08Time (us)Velocity (mm/us) FabryPDV #2PDV #2UNCLASSIFIEDPage 21UNCLASSIFIEDRalph Hodgin12.3um Flyer Fabry to PDV Comparison ShotPDV – Hand Read of the pulse found 5 data points on this 1.2ns impact pulse12.3um Parylene 00.511.522.50.063 0.065 0.067TimePartical Velocity 1889 pulseHand ReadFP-1881UNCLASSIFIEDPage 22UNCLASSIFIEDRalph HodginConclusionsFabry-PerotGraphic – instantly see the velocity/time dataComplex returns easily seenSpeed limited by the fabry cavity (.5ns)Expensive, Room sizePDVMust be analyzed to see the dataComplex returns are seen with additional analysisSpeed limited only by the recording digitizerPortable, less expensive

Fabry-Perot / PDV Comparison

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Fabry-Perot / PDV Comparison

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