This paper reports on a new concept for the sabot-armature configuration of a rail accelerator. The concept is especially useful in the context of a future space launch application. The idea is to use multiple conducting armatures that are incorporated into a non-conducting separable sabot. The latter may be designed in such a manner that like in the rocket technology parts of it that are no longer subjected to the propelling force will be decoupled from the rest leading to a decrease of the total mass to be accelerated. Results of experiments demonstrating the feasibility of the concept on a laboratory scale (Ekin <100 kJ, l <3 m) are presented. First some basics about rail accelerators and the design of solid armatures in particular in order to emphasize the usefulness of intelligent sabot concepts in the case of large masses are given. The functional principle of a rail accelerator is explained as follows: Two stationary rails and a movable sabot including a conducting part (armature) carry a (pulsed) current. The performance of rail launchers is limited by several causes. The most important are sliding electric contact armature-rails, mechanical stability, thermal load wear. The mechanical stability and the thermal load set a limit to the acceleration of a rail accelerator. Once the magnitude of the current density exceeds 1 kA/mm2 the resulting forces reach the yield strengths of the rails and the armatures. Moreover, at greater acceleration duration the thermal load becomes a problem for the armatures being subjected to the current continuously, as well as for the rails due to the high velocities. The experiments show that the velocity of solid armatures is limited to about 2 km/s. At higher velocities the sliding electric contact undergoes a transition to a contact mode characterised by the existence of plasma, either between both rails or between the armature and the rails.
Launch to space using rail accelerators: a new approach to improve the launch efficiency
Abschuß in den Weltraum mithilfe eines Schienenbeschleunigers - ein neuer Ansatz zur Erhöhung der Effizienz beim Weltraumstart
2004
5 Seiten, 11 Bilder, 2 Tabellen, 8 Quellen
Conference paper
English
Antriebskraft , Beschleunigung , elektromagnetisches Feld , elektromagnetisches Triebwerk , experimentelles Ergebnis , Feldverteilung , Führungsschiene , Gasplasma , Gleitkontakt , Hochstromanlage , hohe Geschwindigkeit , kinetische Energie , Konferenzbericht , Laborversuch , Machbarkeitsstudie , magnetische Permeabilität , Magnetohydrodynamik , mechanische Stabilität , Plasmadynamik , Plasmaschalter , pulsierender Strom , Raumfahrttechnik , Raumfahrzeug , Streckgrenze , Stromdichte , Verschleiß , Wärmebelastung
Macroparticle launch velocity control in rail accelerators
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