摘要:

A shaped charge warhead, designed to produce an ideal jet, always has at least some small manufacturing flaws that degrade jet formation. This degradation is reflected in a vague or fuzzy sense when its effect in turn degrades penetration performance. Fuzzy logic was used to relate warhead performance to manufacturing errors. Fuzzy penetration versus standoff points are predicted to lie within a confidence band with boundaries perpendicular to a linear least-squares fit (LLSQ) to 13 well-distributed experimental data points for a shaped charge penetrating semi-infinite S2 Glass composite. On a penetration versus standoff plot, the LLSQ line at zero standoff intercepts the penetration axis at 8.01 charge diameters (CD), and at 20.00 CD standoff (the outer experimental limit) the penetration is 2.89 CD. For any standoff over the experimental range, predicted penetration is within ±11&percent; of the least-squares value at that standoff. This percentage interval forms the upper and lower boundary for the confidence band. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55627

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We demonstrate a new mechanism for annealing silicon that does not involve the direct application of heat as in conventional thermal annealing or pulsed laser annealing. A laser pulse focused to high power on a small surface spot of a neutron-transmutation-doped silicon slab is shown to anneal regionsfar outsidethe illuminated spot where no heat was directly deposited. Electrical activation of donors throughout the slab was uniform and comparable to that of thermally annealed control samples. We conjecture that the annealing was caused by mechanical energy introduced by the laser pulse. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55511

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Debonding of coatings on a substrate is currently achieved by the so-called laser spallation technique. Here, we give an interpretation of the debonding by laser shock based on the impedance mismatch between the substrate and the coating rather than on the spallation process. An analysis in the (pressure-particle velocity) plane coupled with (space-time) diagrams provides the stress history at the interface and shows the possible traction history, depending on the applied pressure loading and the nature of the target. From this study, the different configurations that can lead to a separation of the layers under laser confined irradiation are evidenced according to the impedance mismatch between both components. A case of this analytical survey is experimentally studied. Free surface velocity measurements by the electro-magnetic technique are performed on a 75 &mgr;m-thick aluminum coating stuck on a 1.5 mm-thick copper plate irradiated by various laser intensities in water confined geometry. A debonding threshold is observed on the records. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55512

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The pressure dependence of laser induced decomposition of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) and RDX-d6 has been studied from ambient pressure to 5.2 GPa. RDX samples were loaded in Merrill-Bassett anvil cells and cooled to a minimum of 23 K at the desired starting pressure. Individual samples were each exposed to a single 8 ns pulse of 532 nm light from a Nd:YAG laser. Thermal transport from the decomposing RDX and RDX-d6 into the anvils arrested the decomposition, enabling the identification of intermediates and products formed under high pressure-high heating rate conditions. A two dimensional finite elements model was employed to estimate the quenching rates and heat flow within the samples. Single crystals, pressed powders, and solutions were studied to determine the effect of mechanical stress on the sensitivity towards laser initiation. The threshold energy for reaction initiation and product distribution is given as a function of pressure. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55513

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A high density Z-discharge plasma in a tapered capillary tube was electro-magnetically accelerated by a phased implosion of a capillary Z-pinch. The implosion was just about timed to the plasmoid drift by the shaped capillary wall. The feasibility of high energy acceleration was experimentally demonstrated using a 100 mm long thin capillary and a fast pulse power generator. For filling gas of 100 Pa of Ar, the axial drift velocity of the plasma was7×107&hthinsp;cm/s,which corresponds to 70 keV argon atoms. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55628

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Recent developments have demonstrated the use of pulsed power for producing intense radiation sources (z-pinches) that can drive planar shock waves in samples with spatial dimensions significantly larger than possible with other radiation sources. In this paper, we will discuss the use of z-pinch sources for shock wave studies at multi-Mbar pressures. Experimental plans to use the technique for absolute shock Hugoniot measurements and with accuracies comparable to that obtained with gun launchers are discussed. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.55685

出版商:AIP    

年代:1998

数据来源: AIP