Sliding contact performance of multiple brush armatures

In a previous paper experiments (muzzle velocity v₀<1200 m/s, applied energy per shot E_prim<0.7 MJ) concerning the contact transition of multiple brush armatures were presented and a corresponding physical model was proposed. This work deals with the continuation of these experiments performed at the ISL-railgun facility EMA3 (l=3 m, regular caliber=15×30 mm²). This time, E_prim was increased up to 0.9 MJ. The use of both, quasisegmented rails allowing a higher acceleration due to an increased inductance gradient L´ and a new sabot-technique resulted in v₀ up to 1900 m/s. The contact behavior in the velocity range between 1200 m/s and 1900 m/s is qualitatively clarified and some integral quantities describing the armature performance are given. The quantitative analysis of the armature mass loss shows both, friction and Joule losses playing an important role. The multiple brush armatures used might be designed to show excellent sliding behavior and their contact transition velocities might be greater than 1700 m/s.