EM gun bore life experiments at the Naval Research Laboratory

Meger, R. A.; Cairns, Richard L.; Douglass, S.R.; Huhman, B. M.; Neri, J. M.; Jones, H.N.; Cooper, K. P.; Feng, J.; Brintlinger, Todd; Sprague, J.A.; Michopoulos, John G.; Young, Marcus; DeGiorgi, Virginia G.; Leung, Alan C.; Baucom, Jared N.; Wimmer, Stephanie A.

doi:10.1109/eml.2012.6325173

Cited by 10 publications

(3 citation statements)

References 13 publications

(18 reference statements)

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“…Ref. [2] uses streamer propagation in the conduction channel, however recent post fire analysis [14][15][16] shows the depths of wear are usually within tens of μm, whether there is enough space and time for streamer to develop is questionable. Furthermore, [2] assumes the far field radiation is caused only by the arc formed between the rails, neglecting the contribution from the rails themselves which should be the most dominant antenna like structure.…”

Section: B Simulation Environment and Time Consumedmentioning

confidence: 99%

Electromagnetic radiation of railgun and shielding effects from its structures

Chung¹,

Chuang

2015

2015 Asia-Pacific Symposium on Electromagnetic Compatibility (APEMC)

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The Navy railgun propels its projectile with Lorentz force, and is capable of delivering Mach 7-8 speed for ~15kg weight projectiles. The source of the Lorentz force is a GW pulsed power supply (PPS) that delivers ~1MA current with ~10KV voltage into the railgun load. The electromagnetic radiation of railgun, though most shielded by its metallic cover, leaks out at the final stage when the projectile leaves the barrel and can be a possible EMC issue for on board electronics. We analyse the EM radiation coming from rails and armature of the railgun, and evaluate the shielding effectiveness of various components, also present the far and near field radiation patterns at the final stage of firing. We found most of the forward far field radiation is concentrated at the bore-sight direction due to outside metal casing shielding, and a strong backward far field exists in breech direction due to impedance mismatch between PPS and railgun.

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Section: B Simulation Environment and Time Consumedmentioning

confidence: 99%

Electromagnetic radiation of railgun and shielding effects from its structures

Chung¹,

Chuang

2015

2015 Asia-Pacific Symposium on Electromagnetic Compatibility (APEMC)

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“…Tests show that the high current, high speed, and high pressure cause poor inner environment of the rail, leading to rail damage. In general, the main forms of rail damage are edge grooving, central erosion, planing, and ablation . Erosion is a serious damage, which has the effect of accumulation .…”

Section: Introductionmentioning

confidence: 99%

Analysis of current characteristics of the electromagnetic rail gun based on HHT

Cao

Zhang

2017

IEEJ Transactions Elec Engng

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In this paper, using the B-dot probe at the end of the gun, the B-dot's voltage waveform is measured when the armature is being launched. During the launch process, the magnetic field around the probe changes. According to the change of the magnetic field, the probe generates an induced voltage. The Hilbert spectrum of voltage signal is obtained by the Hilbert-Huang transform (HHT). Based on the Hilbert spectrum, the rail states of the launch system are compared. The results show that the waveforms obtained from the B-dot probes at the rail-gun breech can be used to analyze the whole process of the launch based on HHT.

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“…A large number of launching experiments show that a big chunk of aluminum deposition can be found on the rail surface at the armature-rail contact start-up position. Sometimes, even erosion emerges and generates a back-jet at the rail breech, seriously reducing the bore lifetime [3], [4]. Excessive loss of armature material can lead to transition from a good sliding metal-to-metal contact to a damaging arcing contact in solid-armature railguns.…”

Section: Introductionmentioning

confidence: 99%

Study of Some Influencing Factors of Armature Current Distribution at Current Ramp-Up Stage in Railgun

Tang

Chen

et al. 2015

IEEE Trans. Plasma Sci.

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Current ramp-up is an important stage for a railgun electromagnetic launch system. In lots of launching experiments, a big chunk of deposit aluminum can be found on the rail surface at the start-up position of the armature-rail contact area, sometimes, erosion is even emerged. The transition at current ramp-up is mainly related to local degradation of armature. The larger value of maximum current densities at the rail/armature (A/R) interface would lead to armature local temperature increasing rapidly, which deteriorates the material property of armature, degrades the static electrical contact performance, and reduces the railgun lifetime significantly. In this paper, for restraining start-up transition, several influencing factors of armature degradation and melt are studied based on current concentration. Rail resistivity, rail dimensions, armature resistivity, and the shape of current supply are considered and simulated. At current startup, skin effect and induced current are analyzed, which are considered as the direct factors of armature's current distribution. Armature current distribution and the maximum current density are obtained and compared for each factor. Finally, launching experiments are carried out as the same condition with simulation. On the rail surface at the start-up position of the A/R interface, the depositions reflect the current distribution on armature with different factors influence at the current ramp-up. The results of experiments are in reasonable agreement with simulation description.Index Terms-Armature current distribution, current ramp-up, influencing factors, the maximum current density.

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EM gun bore life experiments at the Naval Research Laboratory

Cited by 10 publications

References 13 publications

Electromagnetic radiation of railgun and shielding effects from its structures

Electromagnetic radiation of railgun and shielding effects from its structures

Analysis of current characteristics of the electromagnetic rail gun based on HHT

Study of Some Influencing Factors of Armature Current Distribution at Current Ramp-Up Stage in Railgun

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