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High-Efficiency Helical Coil Electromagnetic Launcher

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Final rept. 1 Jun 2003-30 Jun 2006

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Technical progress during the reporting period includes the development of new theory for electromagnetic launcher efficiency which is applicable to all constant inductance gradient launcher geometries. This theory also develops methods to predict the performance of different geometry electromagnetic launchers and compare them to each other. A theoretical analysis is also presented to design a helical electromagnetic launcher for a specific volt- amp characteristic. Experimentally measured performance is reported for a 40 millimeter bore helical electromagnetic launcher which is subsequently compared to a one-turn augmented railgun and a conventional railgun operating at comparable scale. Experimental results are also given that demonstrate significant launcher performance benefits by super-cooling the conductor in the armature i.e., liquid nitrogen temperatures Efficiency and scaling relationships for DC i.e., non-induction constant inductance gradient electromagnetic launchers are presented and discussed. Expressions for electromagnetic force, efficiency, back-voltage, and kinetic power are derived and given in terms of electrical circuit parameters. Launcher efficiency is shown to be a simple function of armature velocity and the launchers characteristic velocity. The characteristic velocity characterizes the launcher and is the product of two new parameters the mode constant and launcher constant. Mathematically, the launcher must operate at its characteristic velocity for 50 maximum efficiency. The mode constant reflects the manner in which the launcher is powered and its maximum efficiency. The launcher constant reflects the geometry of the launcher. The two modes of operation presented in this investigation include constant current and zero exit current operation. The ideal electromagnetic launcher concept is developed and defined by operation at 100 maximum efficiency at all velocities.

Subject Categories:

  • Electrical and Electronic Equipment
  • Numerical Mathematics
  • Ammunition and Explosives

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