The ignition element of the Raufoss Multipurpose projectile is an incendiary charge situated in the nose end of the projectile. As the ignition mechanism is influenced by the density distribution of the charge within the ignition cap, it is of vital importance to be able to measure the actual density distributions within test caps, resulting from different nose cap construction parameters, and filling procedures. The authors have used a medical computed tomography (CT) scanner to measure the density profile of such charges. As the projectile cap consists of aluminium, and the charge itself contains elements with atomic numbers close to 20, the task of imaging the cap interior with a medical scanner is close to the limit of what is achievable, and the present work deals with such problems as limited resolution, noise, beam hardening, linearity, calibration, etc. The conclusion is that a medical X-ray scanner is indeed capable of analysing the density distribution for a compacted charge surrounded by a aluminium cap. The CT scanner used in this study was a General Electric, model Pace. The X-ray tube voltage was set at 120 or 140 kV, with currents of 130/160 mA. Scan times were from 4 to 8 seconds. The detector width was set to 1-2 mm and they used a reconstruction filter designed for slightly elevating high image frequencies (a filter called 'bone'). The Multipurpose nose caps are approx. 30-40 mm long, have a maximum diameter of approx. 15 mm, and are made from an aluminum alloy (Z nearly equal 13, p nearly equal 2,8 kg/dm3). The test charge is a powder with a mean atomic number Z nearly equal 15, and densities ranging from 1 to 2 kg/dm3 depending on the filling compression.
Computed tomography in ordnance. Measuring charge density profiles in projectile head caps
Computertomographie in der Waffentechnik. Messung von Sprengstoffdichteprofilen in Geschoßköpfen
1995
8 Seiten, 5 Bilder, 1 Tabelle, 4 Quellen
Conference paper
English
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