[en] Plasma discharge induced by surface-waves in a compact cavity-type microwave ion source is investigated and the model is built up. The axial density profile and the dispersion property of the plasma column are described systematically in consideration of the geometric parameters and the discharge parameters of the discharge tube, such as: the gas pressure, flow rate, the wave angular frequency, and so on. The numerical calculations show that the axial density curve and the wave dispersion acutely depend on the number γ(γ = 1 + d/R, R is the radius of the plasma column, d is the thickness of the tube), the permittivity ε_d and the gas flow and direction. The model is tested with the experimental data determined by A. Sola and S. Davlaud and agreement is achieved