Experiments with brush armatures: new technical solutions

This work presents experimental solutions developed recently at the French-German Research Institute of Saint-Louis (ISL) railgun facility EMA3 (muzzle velocity v₀<1900 m/s, applied energy per shot E_prim<0.9 MJ, l=3 m, cal.=15×30 mm²). New quasi-segmented rail configurations: one advantage of multiple brush armatures is the possibility of developing new armature-rail configurations, which vary the width of the rail as a function of the rail length in order to maximize the multiple brush armature performance. Improved Doppler radar measurements of the projectile dynamics in the launcher: the overall performance of a Doppler system might be limited by the decrease of the signal-to-noise ratio due to the formation of plasma arcs during the shot. A new approach, circumventing this problem, is presented. Parasitic mass is considered as a key problem of railgun technology in general, and of the use of brush armatures in particular. A new idea using the force behavior of multiple brush armatures is presented. Whereas X-ray flash radiographs provide useful information about the force distribution between multiple brushes, the measurement of the current distribution is more difficult. A method to measure the latter by benefiting from the discontinuity of the armatures is presented.