A LINEAR SHAPED CHARGE NEUTRON RADIOGRAPHY PRECISE DETECTION SCHEME
Neutron radiography was researched to detect the linear density of explosive in linear shaped charge (LSC), to determine its distribution uniformity and defective. The clear images of some samples were obtained by neutron radiography, and were processed to obtain the linear density of inner explosive. The defectives such as sparseness, discontinuity and cavity were shown clearly in the images. The method, with more intuitive and more reliable results, is more direct and simpler than existing quality testing methods for LSC, and most important, the method is a non-destructive one. This new method is of significance to the precise test of LSC and its application in precise blasting; in addition, it could be used in quality test of cord type explosive device.
Degradation mechanisms in shaped charge jet penetration
The mechanisms governing the penetration of shaped charge jets over the full range of stand-offs remain only partially understood. This paper explores various potential degradation mechanisms with the aim of identifying those that are most significant to the penetration process. The mechanisms addressed are: particle shape effects, particle separation, the extent of necking, the deposition of jet material and the effects of collisions of the particles with the crater wall. The study consists primarily of hydrocode simulations using the DERA Eulerian code cAst-Euler. In each case the effects of one or more copper particles impacting upon a semi-infinite Rolled Homogeneous Armour target are modelled. It is concluded from the study that particle shape and impact speed can be significant factors contributing to penetration degradation. Collisions at the side of the crater and tumbling of the particles are also likely to be adverse factors.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.