The Transactions of the Korean Institute of Electrical Engineers B (대한전기학회논문지:전기기기및에너지변환시스템부문B)

The Korean Institute of Electrical Engineers (대한전기학회)
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A Study on Effect on Current Density Distribution, Inductance Gradient, and Contact Force by Variation of Armature and Rail Structure

아마츄어 및 레일의 구조 변화에 따른 전류 밀도, 인덕턴스 경도 및 접촉력의 영향 연구

  • Published : 2001.02.01
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Abstract

The distribution of current in the conductors influenced by the armature geometry and velocity is an important parameter for determining performance of an electromagnetic launcher(EML). the electric current in the early launching stage tends to flow on the outer surfaces of the conductors, resulting in very high local electric current density. However, the tendency for current to concentrate on the surface is driven by the velocity skin effect later in launching stage. The high current density produces high local heating and, consequently, increases armature wear which causes several defects on EML system. This paper investigates the effects of rail/armature geometry on current density distribution, launcher inductance gradient (L'), and contact force. Three geometrical parameters are used here to characterize the railgun system. These are the ratio of contact length to root length, relative position of contact leading edge to root trailing edge, and the ratio of rail overhang to the rail height. The distribution of current density, L', contact force between various configurations of the armature and the rail are analyzed and compared by using the EMAP3D program.

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References

  1. G. C. Long, 'Fundamental limits to the velocity of solid armatures in railguns,' The University of Texas at Austin, Dissertation, pp. 171, August 1987
  2. R. A. Marshall, C. Persad, K. A. Jamison, and M. J. Matyac, 'Observation of solid armature behavior,' IEEE Transactions on Magnetics, vol. 31, no. 1, pp. 214-218, January 1995 https://doi.org/10.1109/20.364699
  3. J. J. Price and H. D. Yun, 'Design and testing of integrated metal armature sabots for launch of armor penetrating projectiles from electric guns,' IEEE Transactions on Magnetics, vol. 31, no. 1, pp. 219-223, January 1995 https://doi.org/10.1109/20.364698
  4. F. Kerrisk, 'Current distribution and inductance calculation for railgun conductors,' Los Alamos National Laboratory Report LA-9092-MS, October 1980
  5. K. T. Hsieh, 'A Lagrangian formulation for mechanically, thermally coupled electromagnetic diffusive processes with moving conductors,' IEEE Transactions on Magnetics, vol. 31, no. 1, pp. 604-609, January 1995 https://doi.org/10.1109/20.364626
  6. Scott Levinson, Jerald V. Parker Kuo-ta Hsieh & Bok-ki Kim, 'Electrical and thermal effects of rail cladding,' IEEE Transactions on Magnetics, vol. 35, no. 1, pp. 417-422, January 1999 https://doi.org/10.1109/20.738443