8.1 Seed Sources Basics

FCGs act as energy amplifiers and as such require some initial energy source. In the case of helical FCGs, this initial energy is in the form of magnetic flux between the stator and the armature. Although generator performance is relatively independent of how the initial flux was generated, it is important to note that only the magnetic flux in this region can be utilized during the generator operation. For instance, the magnetic flux within the armature will not be compressed as it expands and in fact is lost. Because the location of the initial magnetic flux is so important, special care must be taken in the design of the seed source to ensure optimal performance. This includes not only spatial considerations but also time of application and duration of seeding flux.

One of the most common ways of seeding a flux compression generator is to apply a current pulse to the stator windings directly or alternately to an outer seed winding. This current pulse can be derived from a simple capacitor discharge into the windings, or from another explosively driven device such as a ferroelectric or ferromagnetic generator. Regardless of the seed generator used, the current rise-time should be short relative to the magnetic flux diffusion into the armature to achieve optimal energy efficiency.

Another consideration in the seeding of FCGs is the timing of the main detonation wave. The main detonation must be time such that the armature...