Cygnus Trigger System

The Cygnus Dual Beam Radiographic Facility consists of two radiographic sources (Cygnus 1 and 2), each with a dose rating of 4 rd at 1 m, and a 1-mm-diameter spot size. The electrical specifications are the following: 2.25 MV, 60 kA, and 60 ns. This facility is located in an underground environment at the Nevada Test Site (NTS). These sources were developed as a primary diagnostic for subcritical experiments (SCEs), which are single-shot high-value events. The SCE program was initiated after the 1992 moratorium on underground nuclear testing in support of stockpile stewardship. In such an application, there is an emphasis on reliability and reproducibility. A robust low-jitter trigger system is a key element for meeting these goals. The trigger system was developed with both commercial and project-specific equipment. Although not a trigger element, Marx is included in the analysis since it is the target of the final trigger and is a source of jitter. In addition to the traditional function of a trigger system, there are novel features added to the Cygnus Trigger System to protect the investment of a high-value shot. Details of the trigger system, including elements designed specifically for a subcritical test application, will be presented. The individual electronic components have their nominal delay, and when assembled, they have a system delay with a measured range of jitter. The shot-to-shot jitter will be assessed both individually and in combination. Trigger reliability and reproducibility results will be presented for a substantial number of shots executed at the NTS.