caa a22 4500 386367728 CHVBK 20180307111942.0 cr unu---uuuuu 161130e198912 xx s 000 0 eng 10.1017/S0022377800014501 doi S0022377800014501 pii (NATIONALLICENCE)cambridge-10.1017/S0022377800014501 Larsson Jonas Department of Plasma Physics, Umeå University, S-90187 Umeå, Sweden Linear and nonlinear geometric optics. Part 1. Constitutive relations and three-wave interaction [Elektronische Daten] [Jonas Larsson] In a weakly dissipative and weakly space-time-varying plasma the propagation of electromagnetic waves may be described by geometric optics. The local tensors governing geometric optics possess approximate symmetries, which become exact in the limit of zero dissipation. These symmetries, which are well known from explicit expressions obtained in various plasma models assuming a homogeneous background, have not previously been created satisfactorily, either with respect to their appearance or to their derivation for an inhomogeneous medium. As an example of the implications of these symmetries, the coupled mode equations for the resonant interaction between three geometric-optics modes are derived in a form such that, in the dissipationless limit, the linear part of the equations conserves wave action. When nonlinear interaction terms are included, the waves are shown to exchange wave action in accordance with the Manley—Rowe relations. Copyright © Cambridge University Press 1989 Journal of Plasma Physics Cambridge University Press 42/3(1989-12), 479-493 0022-3778 42:3<479 1989 42 PLA https://doi.org/10.1017/S0022377800014501 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0022377800014501 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Larsson Jonas Department of Plasma Physics, Umeå University, S-90187 Umeå, Sweden NATIONALLICENCE 773 0- Journal of Plasma Physics Cambridge University Press 42/3(1989-12), 479-493 0022-3778 42:3<479 1989 42 PLA CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge