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Axial radiation reception

Published online by Cambridge University Press:  24 October 2008

Lim Chee-Seng
Affiliation:
Department of Mathematics, University of Malaya, Kuala Lumpur, Malaysia

Abstract

A radiating point source is abruptly switched on and, thereupon, constantly maintained while immersed within a multi-dimensional, non-dispersive, originally uniform, unbounded, propagative medium with transverse isotropy, equivalent to an intrinsic axisymmetry. The number of spatial dimensions concerned is odd. The pertinent radiation problem is posed as a partial differential equation coupled with a preactivation zero condition. This problem is, first, resolved by a Fourier integral, which is then ‘frozen’ onto (i.e. evaluated at points on) the axis of symmetry. Postulating appropriate hyperbolic-type as well as elliptic-type conditions, a systematic reduction of the ‘frozen’ integral is carried out, enabling an analytic exact solution to be constructed with reference to certain phase curves in a phase plane. Away from the source, this solution is valid throughout the symmetry axis except at certain discrete, moving singularities. These fall into three different categories. The behaviour near each typical singularity is estimated. Three significant physical features are demonstrated (as corollaries); namely, the implicit compliance with a radiation principle, the linear interception of the symmetry axis by a Petrow sky's lacuna (associated with the instantaneous point impulse), and, the eventual attainment of either a steady or quiet state after an infinite period. Interpretations are provided in terms of the group velocity. To assist in probing into these various aspects, two appendices are separately included. An application is made to consider magnetically aligned, radiation reception within a field permeated, electrically conducting gas.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1973

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References

REFERENCES

(1)Bazer, J. and Yen, D. H. Y.Comm. Pyre Appl. Math. 22 (1969), 279.CrossRefGoogle Scholar
(2)Bers, L., John, F. and Schechter, M.Partial differential equations (New York, Interscience, 1964).Google Scholar
(3)Bretherton, F. P. and Garrett, C. J. R.Proc. Rop. Soc. (London) Ser. A 302 (1969), 529.Google Scholar
(4)Burridge, R.Proc. Cambridge Philos. Soc. 63 (1967), 819.CrossRefGoogle Scholar
(5)Carrier, G. F., Krook, M. and Pearson, C. E.Functions of a complex variable (New York, McGraw-Hill, 1966).Google Scholar
(6)Courant, R. and Hilbert, D.Methods of mathematical physics, volume 2 (New York, Interscience, 1962).Google Scholar
(7)Duff, G. F. D.Phil. Trans. Roy. Soc. (London) Ser. A 252 (1960), 249.Google Scholar
(8)Gårding, L.Acta Math. 85 (1951), 1.CrossRefGoogle Scholar
(9)Gårding, L.Hyperbolic equations and waves (ed. Froissart, M. –Battelle Seattle 1968 Recontres), pp. 1321. (Berlin, Springer, 1970).CrossRefGoogle Scholar
(10)John, F.Plane waves and spherical means. (New York, Interscience, 1955).Google Scholar
(11)Jones, D. S.Generalized functions. (New York, McGraw-Hill, 1966).Google Scholar
(12)Kulikovskiy, A. G. and Lyubimov, G. A.Magnetohydrodynamics. (Addison–Wesley: Reading, Massachusetts, 1965).Google Scholar
(13)Lighthill, M. J.Fourier analysis and generalized functions (Cambridge, 1958).Google Scholar
(14)Lighthill, M. J.Phil. Trans. Roy. Soc. London Ser. A 252 (1960), 397.Google Scholar
(15)Lighthill, M. J.J. Inst. Math. Appl. 1 (1965), 1.CrossRefGoogle Scholar
(16)Lighthill, M. J.J. Fluid Mech. 27 (1967), 725.CrossRefGoogle Scholar
(17)Miller, G. F. and Musgrave, M. J. P.Proc. Roy. Soc. London Ser. A 236 (1956), 352.Google Scholar
(18)Petrowsky, I. G.Rec. Math. (Mat. Sb.) 17 (1945), 289.Google Scholar
(19)Yen, D. H. Y. and Bazer, J.Comm. Pure Appl. Math. 20 (1967), 329.CrossRefGoogle Scholar