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Current Distribution and Contact Mechanisms in Static Railgun Experiments With Brush Armatures | IEEE Journals & Magazine | IEEE Xplore

Current Distribution and Contact Mechanisms in Static Railgun Experiments With Brush Armatures


Abstract:

The use of brush armatures for accelerating railgun projectiles allows muzzle velocities in excess of 2.5 km/s and contact transition velocities of at least 1.8 km/s in m...Show More

Abstract:

The use of brush armatures for accelerating railgun projectiles allows muzzle velocities in excess of 2.5 km/s and contact transition velocities of at least 1.8 km/s in middle-caliber launchers to be obtained. The technology developed at ISL is based on the use of multiple brush armatures. Asymmetric wear has been observed in dynamic launch experiments when the brushes were separated in shot direction. This indicates the presence of asymmetric current distribution. In this paper, mechanisms determining the current distribution of multiple brush armatures are investigated using a static approach. Experiments were performed using a section of the ISL EMA3 railgun with 270-mm-long rails. It had a caliber of 15 mm \times 30 mm and was connected to a 150-kJ capacitor bank. Three series of experiments focusing on specific parameter variations are presented. The current distributions were recorded using small Rogowski coils placed around the brushes. Magnetoresistive sensors were used for highly local measurements of magnetic fields in the vicinity of the brushes. Results reveal insight into the contact behavior of multiple brush armatures. More specifically, phase transitions at the brush–rail interfaces can be observed. This is typical in dynamic experiments when the current commutates from one brush to another. The experiments are discussed with the help of PSPICE simulations.
Published in: IEEE Transactions on Plasma Science ( Volume: 39, Issue: 1, January 2011)
Page(s): 431 - 436
Date of Publication: 20 September 2010

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