Current Collectors Operating in High Magnetic Fields

An air core, superconducting field coil, self-motored, pulsed homopolar generator has been built and tested. This device uses multiple voltage generating passes and five Tesla magnetic field density to develop open circuit voltage of 500 V. Early testing of this machine showed that the original designs for the motoring and armature current collection systems failed during operation in high external fields. Because this generator is similar to self excited, air core, improved energy devices in the requirement for current collection in high magnetic fields, new designs for both the motoring and armature brushgear systems were developed. A hinged mechanism is used to support the motoring brush, where the current is conducted by a laminated shunt. This design results in significant improvement in sensitivity to contact wear. The armature brushes are compensated in the region of the sliding contact itself, in order to minimize the effect on contact load. An idle (non-current carrying) trailing arm provides dynamic stability. Both designs have been analyzed for thermal and mechanical stability. Static prototypes have been built to verify overall spring rate and fabrication procedures. Dynamic testing of the motoring brush system is scheduled on a high speed contact test system, at slip speed, current density, and duration similar to rated performance in the high voltage homopolar generator