Emack electromagnetic launcher commissioning

Deis, D. W.; Scherbarth, D.W.; Ferrentino, G.

doi:10.1109/tmag.1984.1063096

Cited by 21 publications

(4 citation statements)

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“…This is the famous mass-energy relation of special relativity. For the railgun shot published in [3] the field energy required is E = 3.99 X 10l1 J, whereas the energy actually available in the homopolar generator was only 16.3 X lo6 J. The huge discrepancy rules out explanations in terms of experimental errors.…”

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confidence: 94%

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Railgun recoil and relativity

Graneau

1987

J. Phys. D: Appl. Phys.

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confidence: 94%

“…The railgun provides another opportunity to test relativistic momentum conservation. Let us consider an actual railgun shot reported in [3] in which a mass of m = 0.317 kg was accelerated to a velocity of U = 4200 m s-l with E = 16.3 MJ of kinetic energy stored in the rotor of a homopolar generator. The equation for balance of the projectile momentum p is…”

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confidence: 99%

Railgun recoil and relativity

Graneau

1987

J. Phys. D: Appl. Phys.

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“…Several techniques for EM launch have been studied in the past, but recent successes with a rail-type launcher [2] have spurred interest in EM guns in general and especially in rail guns. The Westinghouse EMACK launcher has accelerated a 3 17-gm armature to 4.2 km/s in a distance of 5 m.…”

Section: Introductionmentioning

confidence: 99%

“…It is an extremely useful quantity that arises in propagation studies [ 13 (e.g., it provides the degree of coherence of the field at two points, the angular distribution of the field, and the field's mean energy) and it determines the signal-to-noise ratio (SNR) in an optical heterodyne receiver [2], [3].…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic field near rail guns

Soper

1989

IEEE Trans. Antennas Propagat.

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meteorological conditions would be more uniform. The similarity in the curve shape indicates that the fluctuations in the 10 min averages are related to atmospheric effects and are not due to random instrument fluctuations.As before, the standard deviations in refractivity obtained from the meteorological instruments are about a factor of four larger than those derived from the receiver fluctuations measured. This is attributed to the path-averaging experienced by the propagating microwave signals.v. RESULTS AND DISCUSSION OF COMPARISONS OF PREDICTED AND MEASURED SIGNAL STRENGTH FLUCTUATIONSMeteorological measurements at eight heights plus the surface made at one location near the RF signal propagation path provided the information required to calculate the refractive index profile and its time variations. The 10 min averaged data sampled on the hour provided the refractivity profile needed by the RF signal prediction model. Calculations were made to estimate the expected signal intensity changes from hour-to-hour at the ten receivers. The predicted changes were compared with the hour-to-hour changes obtained from the averaged 10 min data at each receiver.There was also significant interest in evaluating the ground plane effects on the signal distribution at the receivers. The long term averaged receiver pattern did not correspond to the theoretical model using a ground reflection coefficient of -1. The peak in the measured signal distribution occurred at about 0.8 of the predicted height. The lowered peak could be the result of variations in the grazing angle over the Fresnel zone and the associated variations in reflection phase. The absence of sharp nulls could result from additional multipath signals and the fact that short term refractive changes would tend to cause rapid and extreme changes at the expected null points. The time averaging process used would result in null filling.To establish a reference profile for the prediction model, the reflection coefficient was varied with grazing angle to obtain a best fit to the measured profile "unperturbed" by atmospheric inhomogenities. Variations about this reference profile were then used for comparison of the predicted and measured effects of atmospheric inhomogenities. This is shown in Fig. 6 for eight different levels. The shape of the curves compare best during the evening hours when there is usually less mixing. In addition, the predicted changes are generally a factor of two or more larger than the measured changes. This latter effect can be attributed to the fact that the model predictions are based on meteorological measurements made at one point, but the propagating signal experiences the average meteorological conditions existing over the propagation path.It should be noted that the measured intensity changes at levels 2 and 10 are almost identical in shape and that the measured intensity changes at levels 2 and 6 are mirror images. This indicates that the dominant effect of the refractive change is to shift and stretch or compress the theoretica...

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