https://www.fdd.org/analysis/2019/05/08/shock-wave-generator-for-irans-nuclear-weapons-program/

Shock Wave Generator

Iran was developing and building a nuclear weapons production complex in the early 2000s under the “Amad Plan,” with the goal of manufacturing five nuclear weapons by 2004. This program had moved beyond performing feasibility and scientific studies. Iran had a nuclear weapons design small enough to fit on the Shahab-3 ballistic missile and was creating the wherewithal to develop and make the subcomponents of that design. Some of the components were innovative and complex. The primary subject of this report is one of those subcomponents, the “shock wave generator.”1 This component, which is represented as the green layer under the outer casing in the nuclear explosive schematic (Figure 1), contributed importantly to the miniaturization of Iran’s nuclear weapon design. Its purpose is to uniformly initiate the high explosives, or “main charge,” which in turn compress the nuclear core made from weapon-grade uranium to achieve a supercritical mass and a nuclear explosion. This component falls under the general category of a multi-point initiation (MPI) system.

Information provided to the Agency by the same Member State referred to in the previous paragraph [not included here] describes the multipoint initiation concept referred to above as being used by Iran in at least one large scale experiment in 2003 to initiate a high explosive charge in the form of a hemispherical shell. According to that information, during that experiment, the internal hemispherical curved surface of the high explosive charge was monitored using a large number of optical fibre cables, and the light output of the explosive upon detonation was recorded with a high speed streak camera. It should be noted that the dimensions of the initiation system and the explosives used with it were consistent with the dimensions for the new payload which, according to the alleged studies documentation, were given to the engineers who were studying how to integrate the new payload into the chamber of the Shahab 3 missile re-entry vehicle (Project 111).