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In an explosive experiment, the effects of extra covers of thin plane plate, hollow wedge or cone placed in the front of the cassette protector assembly which consisted of three layers of interspaced aluminum plates were analyzed by comparing the optical densities of the x-ray films inserted between the layers. With the plate cover, all the plates of the protector assembly were severely deformed. And all the films were severely darkened owing to the impacts of deformed plates as well as the transmitted shock waves. With wedge or cone cover, no apparent deformation of the assembly plates was observed, and only the first film showed slight darkening owing to the shock waves. When a large amount of explosive has to be used or the film plane has to be placed very close to an explosion source, the cone type of extra cover can protect the film cassette from the explosive blast without degrading the radiographic image quality.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In high speed x-ray cineradiography, recording individual image frames separately is as important as generating successive flash x-ray pulses. Some researchers resolved the problem by employing multiple pairs of source-camera configuration. In this arrangement each pair of source and camera produces one separate image. So fast decaying image intensifying screens must be used to avoid the overlaps of the images exposed by different sources. Fast decaying screens, however, are not either easily available commercially, nor manufacturable at laboratory. This study proposes a cineradiographic technique which utilizes a conventional long decaying high speed image intensifying screen. The images exposed successively on the screen by multiple flash x-ray sources are sequentially recorded by multiple single frame MCP cameras. The first frame is singly exposed, the second doubly, and so on. The multi-exposed images are reconstructed to a singly exposed one by subtracting the images in the previous frame which contains one less image. Static test results with two-channel configuration revealed that the maximum frame rate of 105 fps could be attainable for shadow radiography.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Detonation waves propagating in a cylindrical high explosive initiated peripherally at one end were photographed by using multislit steak technique. The slit plane consisted of several concentric circular slits and a linear one lying on the center of the circles. One of the interesting facts observed with this multislit configuration was that the detonation wave which appeared symmetric in linear slit streak might not be a circular one. And more details of the wave shapes were recorded in the streak of circular slit with smaller diameter.

Flash radiographic and high speed photographic observations have been made on the particulated shaped charge jets penetrating into water. As a foregoing jet particle impacted water and delivered its kinetic energy to water, the water expanded radially to produce a bubble around the penetrating jet particle and a shock wave ahead of the bubble. This kind of penetration process was succeeded by the next particle and continued until all the jet particles were consumed. Since the jet particles had different velocities and lengths, the contour of the bubbles was not smooth curved but wave packeted. And several discontinuities in the contour were found on the flash radiographs. Based on the hydrodynamic theory of jet penetration, penetration processes of jet particles into water have been calculated. The calculation agreed well with the experiments for short penetration depths, but predicted more at larger depths.

Precise timing for x-ray bursts is crucial in acquiring useful information from flash radiographic experiments. Triggering the flash x-ray system near the muzzle is a difficult task because of the intrinsic nature of the muzzle blast. In this work a compact and reliable triggering method for near muzzle flash radiography is introduced; a piezoelectric pin probe attached at the end of the barrel. These types of probes have not been activated by the precursor shock wave, but they have been activated by the main blast wave only. Reliability in triggering the flash x-ray system has been confirmed throughout a series of flash radiographic experiments near the muzzle for gun barrels with calibers up to 105 mm.