Three experiments done over twenty years on gaps in LX‐17 are described. For the detonation front moving parallel to the gaps, jets of gas products were seen coming from the gaps at velocities 2 to 3 times greater than the detonation velocity. A case can be made that the jet velocity increased with gap thickness but the data are scattered. For the detonation front moving transverse to the gap, time delays were seen. The delays roughly increase with gap width, going from 0–70 ns at “zero gap” to around 300 ns at 0.5–1 mm gap. Larger gaps of up to 6 mm width almost certainly stopped the detonation, but this was not proved. Real‐time resolution of the parallel jets and determination of the actual re‐detonation or failure in the transverse case needs to be achieved in future experiments.
No abstract
An introduction to streak camera geometry, experimental techniques, and limitations are presented. Equations, graphs and charts are includ_ed to provide useful data for optimizing the associated optics to suit each experiment. A simulated analysis is perfonned on simultaneity and velocity measurements. An error analysis is also perfonned for these measurements,,..-utilizing the Monte Carlo method to simulate the distribution of uncertainties associated with simultaneity-time measurements.
Bigplate is an advanced explosive equation of state. (EOS) test. It consists of a point detonator driving a large disc (100 mm radius) of explosive, which pushes a 0.5 mm thick copper or tantalum plate. The plate is observed by a five-beam Fabry-Perot interferometer, which has beams at 0, 10, 20,40 and 80 mm on the plate. A short Fabry gives the jump-off to high accuracy: a long Fabry runs out to IO-15 us. A detailed error analysis is given, with the final velocity measurments considered good to iO.066 mm&s. Jump-offs are measured to 0.01-0.02 ps. Spall is seen in all shots, which creates a time delay on both the first and second velocity plateaus. A 0.1 ps delay in jump-off of unknown origin is also seen at 80 mm. In brder of decreasing explosive ideality, the explosives tired have been LX-14, LX-04 and LX-17. To partially negate the time delays, the data and code runs are overlaid at each radial position between the frst and second plateaus. Traditional JWL's model LX-14 and LX-04 within accuracy, but not so for LX-17. The spa11 may be partly modeled using the pmin model but high resolution zoning is required. At longer times, spall does not appear to affect the explosive energetics. Because it includes diagonal zone crossing, Bigplate occupies a location between simple plate and cylinder tests and truly complex geometries. Hence, an EOS that fails Bigplate is not likely to move on to more complex issues. Bigplate is an excellent testbed for radically new EOS's, and the initial LX-17 mns done with Equilibrium and KINETIC CHEETAH are promising.
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