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Title: Examining the temporal evolution of hypervelocity impact phenomena via high-speed imaging and ultraviolet-visible emission spectroscopy

The temporal evolution of a previously observed hypervelocity impact-induced vapor cloud [Mihaly et al., Int. J. Impact Eng. 62, 13 (2013)] was measured by simultaneously recording several full-field, near-IR images of the resulting emission using an OMA-V high-speed camera. A two-stage light-gas gun was used to accelerate 5 mg Nylon 6/6 right-cylinders to speeds between 5 km/s and 7 km/s to impact 1.5 mm thick 6061-T6 aluminum target plates. Complementary laser-side-lighting [Mihaly et al., Int. J. Impact Eng. 62, 13 (2013); Proc. Eng. 58, 363 (2013)] and front-of-target (without laser illumination) images were also captured using a Cordin ultra-high-speed camera. The rapid expansion of the vapor cloud was observed to contain a bright, emitting exterior, and a darker, optically thick interior. The shape of this phenomenon was also observed to vary considerably between experiments due to extremely high-rate (>250 000 rpm) of tumbling of the cylindrical projectiles. Additionally, UV-vis emission spectra were simultaneously recorded to investigate the temporal evolution of the atomic and molecular composition of the up-range, impact-induced vapor plume. A PI-MAX3 high-speed camera coupled to an Acton spectrograph was utilized to capture the UV-vis spectra, which shows an overall peak in emission intensity between approximately 6–10 μs after impact trigger, corresponding to an increased quantitymore » of emitting vapor/plasma passing through the spectrometer slit during this time period. The relative intensity of the numerous spectral bands was also observed to vary according to the exposure delay of the camera, indicating that the different atomic/molecular species exhibit a varied temporal evolution during the vapor cloud expansion. Higher resolution spectra yielded additional emission lines/bands that provide further evidence of interaction between fragmented projectile material and the 1 mmHg atmosphere inside the target chamber. A comparison of the data to down-range emission spectra also revealed differences in the relative intensities of the atomic/molecular composition of the observed vapor clouds.« less
Authors:
 [1] ; ; ;  [2]
  1. Department of Chemistry, University of Leicester, Leicester LE1 7RH (United Kingdom)
  2. Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States)
Publication Date:
OSTI Identifier:
22308503
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM; CAPTURE; CYLINDRICAL CONFIGURATION; EMISSION; EMISSION SPECTRA; EMISSION SPECTROSCOPY; EXPANSION; INTERACTIONS; PLASMA; RESOLUTION; SPECTROMETERS; TARGET CHAMBERS; ULTRAVIOLET RADIATION; ULTRAVIOLET SPECTRA; VISIBLE RADIATION; VISIBLE SPECTRA