High Current and High Current Density Pulse Tests of Brushes and Collectors for Homopolar Energy Stores

The incentive exists to use high collector current densities in pulsed duty homopolar generators, the current densities of interest being in the range of 15--45 MA/m2. Tests have been conducted in which current pulses of up to 0.25 MA with an equivalent pulsewidth of 0.3 s have been passed between pancake brush assemblies and fiat plate collectors with collector current densities of up to 78 MA/m²and current densities in the brush fingers of 570 MA/m2. The currents carried per brush have been a comparatively low 800 A. These tests have been successful and are providing the data necessary for the design of the all-iron-rotating homopolar pulse generators.