Experimental Investigation of a UHF Radio Link to a Railgun Projectile

Railguns are electrical accelerators with the experimentally proven capability to accelerate masses in the range from milligrams to tens of kilograms to velocities in excess of several kilometers per second. A railgun projectile connects via its armature to the current-carrying rails, thus providing a short circuit. To understand the processes during the acceleration, it is highly desirable to measure parameters such as current density, magnetic field strength and distribution, instantaneous acceleration, voltage drop across the armature rail interface, etc., directly in the vicinity of the short circuit. A radio link to the projectile is therefore an attractive option to allow the access to data from sensors placed inside the projectile during the acceleration. In this paper, a UHF radio link from the laboratory to the accelerated projectile is studied using a railgun being installed at the French-German Research Institute of Saint-Louis.