Examining the X-Ray radiographs of the linear collapse and the jet formation processes it can be seen that the space between the end of the straight and continuous jet and the slug is usually filled with small particles that do not look like an integral part of the jet. This section of the jet is named the Appendix. This is the transition zone between the jet and the slug. The experimental evidences as well as the numerical simulation results are presented. It was found that the Appendix is a stand-alone section of the jet, as it can be characterized by a specific collapse angle and velocity gradient. In addition, the Appendix breaks up time is much shorter than that of the main jet and the average velocity difference between each two particles in the Appendix is much higher than that of the main stream of jet droplets. By conducting a detailed 2D numerical simulation it was found that there is a way to define this transition zone. By defining this zone the tail of the jet is also well defined. As the tail of the jet is well defined it is easier to design more efficient shaped charges. Once the lowest jet velocity needed for a given penetration is known the tail of the jet can be designed to meet this speed.
Meir Mayseless, Meir Mayseless,
"Appendix: a new section of a shaped-charge jet", Proc. SPIE 4183, 24th International Congress on High-Speed Photography and Photonics, (17 April 2001); doi: 10.1117/12.424349; https://doi.org/10.1117/12.424349