Experimental observation of nonspherically-decaying radiation from a rotating superluminal source

Ardavan, Arzhang; Hayes, W.; Singleton, John; Ardavan, H.; Fopma, J.; Halliday, Dorothy

doi:10.1063/1.1787591

Cited by 17 publications

(40 citation statements)

References 12 publications

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“…The analysis is based upon current practical devices for investigating emission from accelerated superluminal sources [1, 5,6]; these devices (Appendix A) produce polarization currents whose distribution patterns rotate and oscillate with two incommensurate frequencies (ω and Ω). Although the only frequencies entering the production of the emitting currents are mω and Ω (see Table 1), we find that the broadband signals from such devices contain frequencies that are higher than the oscillation frequency Ω by a factor of the order of (Ω/ω) 2 .…”

Section: Discussionmentioning

confidence: 99%

“…(7) can be implemented by an experimentally-viable device [5,6] whose construction and operation only entail oscillations at the two frequencies mω and Ω (see Appendix A). As a source of radiation at frequencies which cannot be normally generated in the laboratory, except by means of large-scale facilities such as synchrotrons or free electron lasers, the potential practical significance of such a device is clearly enormous [1]; as we have shown in Section VIII, the efficiency is large enough for many spectroscopic applications to be viable.…”

Section: Discussionmentioning

confidence: 99%

“…(7) can be implemented by an experimentally viable device [5,6] whose construction and operation only entail oscillations at the two frequencies mω and Ω.…”

Section: Appendix A: Practical Implementation Of the Sourcementioning

confidence: 99%

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Frequency spectrum of focused broadband pulses of electromagnetic radiation generated by polarization currents with superluminally rotating distribution patterns

Ardavan

Singleton

2003

J. Opt. Soc. Am. A

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We investigate the spectral features of the emission from a superluminal polarization current whose distribution pattern rotates with an angular frequency ω and oscillates with an incommensurate frequency Ω > ω. This type of polarization current is found in recent practical machines designed to investigate superluminal emission. Although all of the processes involved are linear, we find that the broadband emission contains frequencies that are higher than Ω by a factor of the order of (Ω/ω)2 . This generation of frequencies not required for the creation of the source stems from mathematically rigorous consequences of the familiar classical expression for the retarded potential. The results suggest practical applications for superluminal polarization currents as broad-band radiofrequency and infrared sources.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Frequency spectrum of focused broadband pulses of electromagnetic radiation generated by polarization currents with superluminally rotating distribution patterns

Ardavan

Singleton

2003

J. Opt. Soc. Am. A

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“…In order that the flux of energy remain the same across all cross sections of the subbeam, therefore, it is essential that the Poynting vector associated with this radiation correspondingly decay more slowly than that of a conventional, spherically decaying radiation: as R P −1 , rather than R P −2 , within the bundle of cusps that emanate from the constituent volume elements of the source and extend into the far zone. This result, which also follows from the superposition of the Liénard-Wiechert fields of the constituent volume elements of a rotating superluminal source [9,10], has now been demonstrated experimentally [2].…”

Section: Introductionmentioning

confidence: 85%

“…Moving sources of electromagnetic radiation whose speeds exceed the speed of light in vacuo have already been generated in the laboratory [1][2][3][4]. These sources arise from separation of charges: their superluminally moving distribution patterns are created by the coordinated motion of aggregates of subluminally moving particles.…”

Section: Introductionmentioning

confidence: 99%

Fundamental role of the retarded potential in the electrodynamics of superluminal sources

Ardavan

Singleton

et al. 2008

J. Opt. Soc. Am. A

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We calculate the gradient of the radiation field generated by a polarization current with a superluminally rotating distribution pattern and show that the absolute value of this gradient increases as R 7/2 with distance R, within the sharply focused subbeams that constitute the overall radiation beam from such a source. In addition to supporting the earlier finding that the azimuthal and polar widths of these subbeams become narrower (as R −3 and R −1 , respectively), with distance from the source, this result implies that the boundary contribution to the solution of the wave equation governing the radiation field does not always vanish in the limit where the boundary tends to infinity (as is commonly assumed in textbooks and the published literature). There is a fundamental difference between the classical expression for the retarded potential and the corresponding retarded solution of the wave equation that governs the electromagnetic field: while the boundary contribution to the retarded solution for the potential can always be rendered equal to zero by means of a gauge transformation that preserves the Lorenz condition, the boundary contribution to the retarded solution of the wave equation for the field may be neglected only if it diminishes with distance faster than the contribution of the source density in the far zone. In the case of a rotating superluminal source, however, the boundary term in the retarded solution for the field is by a factor of the order of R 1/2 larger than the source term of this solution, in the limit where the boundary tends to infinity. This result is consistent with the prediction of the retarded potential that the radiation field generated by a rotating superluminal source decays as R −1/2 , instead of R −1 , and explains why an argument based on the solution of the wave equation governing the field in which the boundary term is neglected (such as that presented by J. H.Hannay) misses the nonspherical decay of the field. Given that the distribution of the radiation field of an accelerated superluminal source in the far zone is not known a priori, to be prescribed as a boundary condition, our analysis establishes that the only way one can calculate the free-space radiation field of such sources is via the retarded solution for the potential. Finally, we discuss the applicability of these findings to pulsar observational data: the more distant a pulsar, the narrower and brighter its giant pulses should be. * Electronic address: jsingle@lanl.gov 2

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Light in Free-Space and the Cosmos

Vanderwerf

2017

The Story of Light Science

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Experimental observation of nonspherically-decaying radiation from a rotating superluminal source

Abstract: Lepton flavor violating rare muon decays and future prospects AIP Conf. Proc. 435, 261 (1998); 10.1063/1.56196 J/ψ radiative decay to two pseudoscalar mesons from Mark III AIP Conf.

Cited by 17 publications

References 12 publications

Frequency spectrum of focused broadband pulses of electromagnetic radiation generated by polarization currents with superluminally rotating distribution patterns

Frequency spectrum of focused broadband pulses of electromagnetic radiation generated by polarization currents with superluminally rotating distribution patterns

Fundamental role of the retarded potential in the electrodynamics of superluminal sources

Light in Free-Space and the Cosmos

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