Анотація:
The resonance properties of plasma cylinder are carried out for nonzero axial wave vector. Waves with frequency greater then ion cyclotron frequency but less then electron frequency are considered. From Maxwell equations we get the system of two coupling differential equations of second order for these waves. There exist two types of coaxial waves in the vacuum gap. One of them has zero axial electric field (TE-mode). This is the analog of azimuthal surface waves. Another one has zero axial magnetic field (TB-mode). As it is shown, in the broad range of plasma and device parameters the resonance frequencies of TB-mode are close to resonance frequencies of TEmode. This leads to effective coupling of these modes and energy transfer from one mode to another. The time of transfer is much shorter, then collisional absorption time. As an consequence, the wave fields change significantly in plasma and vacuum.