9.1 Dual Stage Generator

As we have outlined in Chap. 5 and also Chap. 7.2, the flux or energy multiplication of single stage FCGs is severely limited. This is in particular true if a load with rather high impedance, say several micro Henries or tens of Ohms is connected to the FCG output. The performance of a single stage FCG would be dismal if fired into such a load. Typically, a single stage FCG would exhibit only acceptable performance if fired into a load with an impedance of two orders of magnitude lower (several 10 nano Henries or hundreds of milli Ohms).

Experiments on the performance of dual stage FCGs with respect to utilizing them as a driver for inductive energy storage with a fuse open switch were carried out in the 90s, e.g. [Leo96], or more recently [Neu03]. We will present in Chap. 9.1 what it takes to drive 40 kA through a 3 ?H load utilizing a dual stage FCG with a 25 mm armature diameter.

9.1.1 Performance by Stage

The smallest wire pitch used for the staged FCG was set to 1.25 mm. Following the relationship between the armature's expansion angle, ?, and the pitch, p,

(9.1)

partial turn-skipping can be avoided [Che86] if the armature is round and centered with respect to the helix within ? a ~ 0.08 mm, cf. Chap. 4. We consider this required level of accuracy as only moderate so that we...