Static and quasi-static models for the magnetic field of a railgun

Coburn, William O.

doi:10.1109/20.364609

Cited by 9 publications

(8 citation statements)

References 3 publications

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“…The railgun inductance gradient, L', is taken as, L divided by I, or 0.52 pWm. This leads to a muzzle exit velocity of 668 &sec, whereas the measured value (averaged over eight shots) is 562 &sec [2]. A rigorous derivation of the force,& shows that an efficiency factor is required to account for that part of L which is involved in the armature acceleration process [6].…”

Section: Resultsmentioning

confidence: 98%

“…Fig. 8 shows fair agreement where the discrepancy after the peak can be reduced by using L' = 0.39 pH/m [2]. Fig.…”

Section: B H;fieldmentioning

confidence: 87%

“…armature current distributions can be readily described by the analytic model; however, the armature field is not as well predicted. An immediate refinement is to use the experimental armature position, which is measured every two inches down the length of the barrel [2]. Although this leads to a model that is not completely analytic, it should reproduce the time history of the measured data and under-predict the amplitude.…”

Section: Discussionmentioning

confidence: 99%

“…A capacitor-based railgun, accelerating an 11.1-gm projectile, is used as a test bed to validate theoretical models [l], [2]. An analytical solution is used to predict the transient H-field for the railgun parameters.…”

Section: Introductionmentioning

confidence: 99%

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Electromagnetic field measurements near a railgun

Coburn

DeTroye

et al. 1995

IEEE Trans. Magn.

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Abstmct-Electromagnetic (EM) field measurements were conducted near a 15-mm squarebore railgun accelerating a metal armature. Under shorted rail conditions the EM environment is quasi-static and directly related to the rail environment is more complex and can indude nonlinear effects such as muzzle arcing. Electric and magnetic field measurements were designed to characterize the transient EM environment external to a capacitor-based railgun. Selected data are presented to demonstrate the time history and the spatial variation of the measured EM environment. Analytical results, assuming a quasi-static armature acceleration, are induded for comparison. Good agreement in amplitude, waveform, and spatial variation is obtained with a filament current model. with a dielectric %ore-rider," as shown in Fig. I@) of [2]. The power supply is composed of four capacitors discharged into a load plate (roughly 2 m behind the breech), which is connected to the rails with a "hempolar" CUTent distribution. under Operational conditions the EM (ips, sh-conductor) cable. H-field measurements near this Power Supply d

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Section: Resultsmentioning

confidence: 98%

“…Fig. 8 shows fair agreement where the discrepancy after the peak can be reduced by using L' = 0.39 pH/m [2]. Fig.…”

Section: B H;fieldmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electromagnetic field measurements near a railgun

Coburn

DeTroye

et al. 1995

IEEE Trans. Magn.

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“…Since the calibre and length of the electromagnetic railgun are far shorter than the wavelength of the electromagnetic field, the displacement current can be ignored. The railgun can be considered a quasi-static system [18]. Combined with the differential form of Maxwell's equations and Ohm's law, the magnetic diffusion equation during electromagnetic launch can be obtained as follows [19]:…”

Section: Mathematical Model Of the Magnetic Field Environment For An ...mentioning

confidence: 99%

The Influence of projectile shielding on the internal magnetic field during an electromagnetic launch

Yang¹,

Liu²,

Li³

et al. 2022

J. vibroeng.

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Compared with a conventional propulsion system, an electromagnetic railgun is characterized by an in-bore pulsed high magnetic field. However, the dynamic distribution of the magnetic field in the projectile has rarely been experimentally studied. To this end, this paper discusses the possibility of utilizing magnetic field environment information. An equivalent model of an electromagnetic railgun is established by using the finite element method. Based on the magnetic diffusion equation and the Biot-Savart law, the in-bore magnetic induction is determined. The velocity skin effect and projectile shielding are considered in the model. Furthermore, the magnetic measurement method is presented to validate a simulation result. The results obtained from the simulation and experiment show that package shielding affects the pulse width and amplitude of the internal value. The peak magnetic induction of low carbon steel and copper is reduced by 33.6 %, and the pulse width lags by 2.7 ms. Moreover, projectile shielding has a substantial influence on the timing accuracy during launch, and the time error reaches approximately 18 %. Therefore, the in-bore magnetic field is a practical signal for the control module since it considers the influence of different projectile shields.

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