Plane wave generator

Various other explosive plane-wave generators have been designed (Deal, 1962 Fowles, 1972), but they all make use of an angular relation which... 

The peak pressures attainable with explosive facilities can be greatly enhanced, and the initial peak pressure can be better sustained by using a plane-wave generator to accelerate a flyer plate, which then impacts a flat specimen as shown in Fig. 3.2. This technique will generate peak pressures up to a few hundred GPa. (McQueen and Marsh, 1960 McQueen et al., 1970). 

Figure 3.2. Explosive plane-wave generator used to accelerate a flyer plate for planar impact on a specimen.

The high explosives, baratol or Composition B-3, are used to produce the plane wave loading into the driver plates. These explosives have been widely studied in substantial work at Los Alamos. Plane waves are introduced into the explosive pads with either P-22 or P-40 plane-wave generators developed at Los Alamos. The Bear system is based on the 56 mm diameter of the P-22, while the larger sample size Bertha system is based on the 102 mmdiam of the P-40. More details on sample dimensions are reported by Graham [87G03]. 

By measuring the terminal velocity of a plate driven by a planar detonation one can, in principle, obtain y/2E for the driver expl by using Eqn (14). In practice, this approach is complicated by the necessity of using a plane wave generator to produce a planar detonation in the driver expl... 

Usually a plane wave generator (PWG) consists of several different expl components, some or all of which are likely to be different expls from the main driver charge. Obviously the PWG contributes energy to projecting the plate, and an estimate of its contribution must be made before one can determine y/2E for the main driver charge. The procedure adopted in Ref 14 for correcting for the presence of a PWG is as follows. Let and h be the respective thicknesses of the main driver charge and the metal plate and pc and pm their respective densities. 

Application of force to a solid puts the solid under stress. Stress results in strain within the solid atoms or molecules of which the solid is composed are displaced from their unstressed locations. When a solid is deformed, the displacement of each particle from its original position is represented by a displacement vector u(x,y,z,t). In general, the displacement has components, which vary continuously from point to point in the solid, in the x, y, and z directions. A plane wave generates displacements that vary harmonically in the direction of wave propagation if this is the x direction, for example, it may be represented as [1] ... 

Figure 5.1. (a) Plane wave generator and recovery system (b) cross-sectional view of the cylindrical capsule. The arrow shows the direction of shock wave propagation... 

Fig. 10.3 Generation of high dynamic pressures with chemical explosives (a) cylindrical scheme, (b) planar direct-contact scheme, (c) planar scheme with explosively accelerated impactor plate. 1 detonator, 2 explosive, 3 ampoule, 4 sample, 5 plane wave generator, 6 layer of inert material, 7 impactor plate...

Fig. 7.2 Schematic of plane wave generation for acoustic measurement using 2-microphone impedance tube...

Figure 1.8. Plane wave generator with two explosives of differs detonation velociti ...

Three types of plane wave generators for explosive systems used in generating dynamic material properties make use of the properties of Baratol and Composition B to form effective lenses. Baratol s slow detonation velocity and Composition B s high detonation velocity, if used in the proper configuration, can convert a spherically diverging wave into an approximate plane wave. The P-40, P-081, and P-120 lenses were used until the middle 1990 s. 

Each plane wave generator is designed to produce a plane shock wave at the upper Baratol surface of the device. The generators use the lens effect of a Baratol cone, and the lower transit velocity therein, to mold the somewhat spherical spreading detonation waves into planar patterns as they proceed. 

Thus the calculated pressure gradients across the lens are probably less steep than those actually present in most plane wave generators. 

George H. Pimbley, Charles L. Mader, and Allen L. Bowman, Plane Wave Generator Galculation , Los Alamos National Laboratory report LA-9119 (1982). 

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