Optical filters to exclude non-Doppler-shifted light in fast velocimetry

Goosman, D.R.; Avara, George R.; Wade, James T.; Rivera, Anthony T.

doi:10.1117/12.516818

Cited by 4 publications

(3 citation statements)

References 2 publications

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“…In 2003 David Goosman from LLNL [4] used a single optical fiber (go and return) embedded either in an inert material or in a high explosive connected to a Fabry-Pérot velocimeter in order to measure shock or detonation wave velocity. With PDV technique, this kind of experiment is much easier.…”

Section: Methodsmentioning

confidence: 99%

Nitromethane ignition observed with embedded PDV optical fibers

Mercier

Bénier

Frugier

et al. 2010

EPJ Web of Conferences

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Abstract. For a long time, the nitromethane (NM) ignition has been observed with different means such as high-speed cameras, VISAR or optical pyrometry diagnostics. By 2000, David Goosmann (LLNL) studied solid high-explosive detonation and shock loaded metal plates by measuring velocity (Fabry-Pérot interferometry) in embedded optical fibers. For six years Photonic Doppler Velocimetry (PDV) has become a major tool to better understand the phenomena occurring in shock physics experiments. In 2006, we began to use in turn this technique and studied shock-to-detonation transition in NM. Different kinds of bare optical fibers were set in the liquid; they provided two types of velocity information; those coming from phenomena located in front of the fibers (interface velocity, shock waves, overdriven detonation wave) and those due to phenomena environing the fibers (shock or detonation waves). We achieved several shots; devices were composed of a high explosive plane wave generator ended by a metal barrier followed by a cylindrical vessel containing NM. We present results.

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Section: Methodsmentioning

confidence: 99%

Nitromethane ignition observed with embedded PDV optical fibers

Mercier

Bénier

Frugier

et al. 2010

EPJ Web of Conferences

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“…The tip is shocked and cut continuously with the detonation. In order to get a clear signal, the front curvature of the shocked silica at the end of the fiber needs to be concave [4] and a Fabry-Pérot filter needs to be put in place to filter non Doppler-shifted light [5]. If the front curvature is convex, as at low detonation velocity, no signal is collected.…”

Section: Introductionmentioning

confidence: 99%

Optimization of detonation velocity measurements using a chirped fiber Bragg grating

et al. 2015

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Dynamic measurements of detonation velocity profiles are performed using long Chirped Fiber Bragg Gratings (CFBGs). Such thin probes, with a diameter of typically 150 µm, are inserted directly into a high explosive sample or simply positioned laterally. During the detonation, the width of the reflected optical spectrum is continuously reduced by the propagation of the wave-front, which physically shortens the CFBG. The reflected optical intensity delivers a ramp down signal type, which is directly related to the detonation velocity profile. Experimental detonation velocity measurements were performed on the side of three different high explosives (TNT, B2238 and V401) in a bare cylindrical stick configuration (diameter: 2 inches, height: 10 inches). The detonation velocity range covered was 6800 to 9000 m/s. The extraction of the detonation velocity profiles requires a careful calibration of the system and of the CFBG used. A calibration procedure was developed, with the support of optical simulations, to cancel out the optical spectrum distortions from the different optical components and to determine the wavelength-position transfer function of the CFBG in a reproducible way. The 40-mm long CFBGs were positioned within the second half of the three high explosive cylinders. The excellent linearity of the computed position-time diagram confirms that the detonation was established for the three high explosives. The fitted slopes of the position-time diagram give detonation velocity values which are in very good agreement with the classical measurements obtained from discrete electrical shorting pins.

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“…The velocimetry system used in these experiments is a custom dual-cavity Fabry-Perot velocimeter equipped with a special Fabry-Perot filter to preferentially reduce the nonDoppler shifted component relative to the Doppler-shifted signal. This system has been previously described in some detail [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Propagation or failure of detonation across an air gap in an LX-17 column: continuous time-dependent detonation or shock speed using the Embedded Fiber Optic (EFO) technique

Hare¹,

Chandler²,

Compton³

et al. 2008

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The detailed history of the shock / detonation wave propagation after crossing a roomtemperature-room-pressure (RTP) air gap between a 25.4 mm diameter LX-17 donor column and a 25.4 mm diameter by 25.4 mm long LX-17 acceptor pellet is investigated for three different gap widths (3.07, 2.08, and 0.00 mm) using the Embedded Fiber Optic (EFO) technique. The 2.08 mm gap propagated and the 3.07 mm gap failed and this can be seen clearly and unambiguously in the EFO data even though the 25.4 mm-long acceptor pellet would be considered quite short for a determination by more traditional means such as pins.

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Optical filters to exclude non-Doppler-shifted light in fast velocimetry

Abstract: This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author.

Cited by 4 publications

References 2 publications

Nitromethane ignition observed with embedded PDV optical fibers

Nitromethane ignition observed with embedded PDV optical fibers

Optimization of detonation velocity measurements using a chirped fiber Bragg grating

Propagation or failure of detonation across an air gap in an LX-17 column: continuous time-dependent detonation or shock speed using the Embedded Fiber Optic (EFO) technique

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