Forced oscillations generated by a point antenna in a drifting plasma

Drift effects on forced oscillations generated by an oscillating antenna are analysed in two cases: (i) For the first a Water Bag model is considered with temperature T => O (with a special treatment for T = 0). A mixed analytical and numerical method is used. Radiation diagrams at different distances from the antenna give the behaviour of the potential. The existence of a radiation cone of Cherenkov type is pointed: outside a cone centered on the drift direction with angle α given by α = Arcsin √ 3p, the potential is strictly independent of the temperature. On the other hand, the bulk of thermal effects are concentrated in an inner cone of smaller angle given by Bohm and Gross relation. Between these two cones, precursor effects appear. (ii) In the second case for which the normalisation of the distances is made classically in term of Debye length, a Maxwellian plasma is represented by a Multi Water Bag model with 60 bags. The integration is performed by the same analytico-numerical method. The topology of the poles is discussed and the problems introduced by the choice of the model are pointed out. The difficulties lessen with increasing drift velocity. Radiation diagrams for low drift velocity (Vsub(D) = 0.35 Vsub(T)) and ω 1.2 ωsub(p) are given at various distances from the source. (author)