High-Current Brushes, Part I: Effect of Brush and Ring Materials

Experiments were conducted to assess the potential for extending the excellent performance of conventionally loaded brushring current collection systems which operate in inert gas environments to much higher current densities. Recent advanced design machines require current collection systems capable of efficient continuous operation at densities to at least 150 A/cm². Based on screening test data presented here, the present state-of-the-art practice of 10 A/cm²brush current density is extendible to at least 80 A/cm², the limit of our test range. Commercially available graphite brushes containing 65 to 75 weight percent (w/o) silver combined with high-strength highconductivity copper alloy slip rings are recommended for more extensive testing at higher current densities in more sophisticated test machines.