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Standing cyclotron harmonic waves below the second harmonic are observed using the noise radiation of a mercury discharge tube a t 1465 MHz. From the positions of the Buchsbaum-Hasegawa resonances the density profile and the electron temperature are derived, these parameters agree quite well with the behaviour of the collision-free, magnetized plasma column.X onedimensional model applicable to our waveguide geometry is developed taking into account linear excitation of cyclotron harmonic waves by a quasistationary external field in a bounded plasma.Absorption and excitation are controlled by the scale length L, a t the hybrid point and a coupling length 1, introduced by Eq. (20); the electron gyration radius re, scale length L,, coupling length 1, and slab thickness 2a obeying the relation I , < I, = L, < 2a. The main absorption is caused by enhanced collisional damping a t the upper hybrid region and only a small fraction being dissipated in the wave mode, though its field strength is largecompared with that at the plasma boundary An estimation of the mean field strength within the coupling region shows, that such a low power as 1 mW/cmz absorbed in the hybrid region may produce fieldstrength exceeding the typical threshold values for non-linear excitation mechanism.(4dW F w 6).

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