Author Institution: Lawrence Livermore National LaboratorySlides presented at the 2nd Annual Photonic Doppler Velocimetry (PDV) Workshop held at Lawrence Livermore National Laboratory, Livermore, California, August 16-17, 2007

Bonner, Randy

Hester, Daron

Solberg, Jerome

Strand, Oliver T.

White, Dan

Whitworth, Tony L.

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Processing Oscillatory Data with the PDV (U)Ted Strand, Randy Bonner,Daron Hester, Jerome Solberg,Dan White, Tony Whitworth Lawrence Livermore National LaboratoryThis work was performed under the auspices of the U.S. Department of Energy by the University ofCalifornia, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.2nd Annual PDV WorkshopAugust 16-17, 2007UNCLASSIFIEDUNCLASSIFIEDWe recently fielded the PDV on a series ofpulsed power testsUNCLASSIFIEDUNCLASSIFIED UNCLASSIFIEDUNCLASSIFIEDcurrentx x x x x x x x x x x x x x x x x x x xcurrentLarge magnetic pressuretends to collapse inner tubeThe test fixture provides validation datafor new ALE3D codesWe had 4 probes mounted at the mid-planeat 90 degree anglesUNCLASSIFIEDUNCLASSIFIED This portable rack holds a 4-channelPhotonic Doppler Velocimeter System2 W CW laserCustomfiber/detectorchassisFastDigitizingScopeShock-mountedcarrying casewith wheelsUNCLASSIFIEDUNCLASSIFIEDWe were told to expect low velocities(less than 100 m/s)UNCLASSIFIEDUNCLASSIFIEDPDVDetectorChassisDigitizerLaserScreenRoomHi-BayTriggerTimingFid12 34Note: the probe numbering schemeis as seen from the high-current cables.40 µs/div100 ps/pt100 mV/divThe beat amplitude goes to zero at zero velocitywhen the moving surface changes directionUNCLASSIFIEDUNCLASSIFIED-0.2-0.10.00.10.2Beat Amplitude (volts)100usec806040200Time (µs)The spectrogram looks empty becausethe velocities are so lowUNCLASSIFIEDUNCLASSIFIED30002000100000 100 200 300 µsm/sProcessed with 1.64 µs FT windowsExpand the image near f = 0UNCLASSIFIEDUNCLASSIFIED30002000100000 100 200 300 µsm/sProcessed with 1.64 µs FT windowsThe spectrogram shows the oscillatory behaviorUNCLASSIFIEDUNCLASSIFIED10864200 50 100 150 200 (µs)Velocity (m/s)Analyzing this is very cumbersomeradiallyinwardradiallyoutwardetc….This laser has a sideband at 1.5 GHzExpand the image around the sidebandUNCLASSIFIEDUNCLASSIFIED30002000100000 100 200 300 µsm/sProcessed with 1.64 µs FT windowsUNCLASSIFIEDUNCLASSIFIED1165 m/sWe see the sum and difference velocitieson either side of the 1.5 GHz sidebandUse the analysis code to extractthe desired velocitiesUNCLASSIFIEDUNCLASSIFIEDUse the analysis code to extractthe desired velocitiesUNCLASSIFIEDUNCLASSIFIEDExtract the velocity time historyfrom the spectrogramUNCLASSIFIEDUNCLASSIFIED11751170116511601155Apparent Velocity (m/s)160140120100806040200Time (µs)Sideband velocity= 1164.62 m/sSubtract the sideband  velocity and integrateto obtain displacement vs timeUNCLASSIFIEDUNCLASSIFIED-10-50510Velocity (m/s)160140120100806040200Digitizer Time (µs)-150-100-50050100Displacement (µm)160140120100806040200Time (µs)This analysis is much easierthan working withthe baseband solutionVelocity vs TimeDisplacement vs TimeintegrateConclusionsWe used the PDV to obtain data from oscillatory motionsAnalyzing the baseband velocity is cumbersomeFortunately, our laser has a 1.5 GHz sidebandAnalyzing the data around the sideband is much easierMoral: a sideband in your laser is not always bad, but we will sendthe laser to the shop after this series of experiments is overUNCLASSIFIEDUNCLASSIFIED

Processing Oscillatory Data with PDV

https://kb.osu.edu/bitstream/1811/52672/1/PDV_2007_Strand_OscillatoryVelocities.pdf

Processing Oscillatory Data with PDV

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