Bohm criterion in a magnetized plasma sheath is investigated with a fluid model.The upper and lower limits for the sheath criterion in different states of applied magnetic field are studied. The results from numerical simulation reveal that the magnetic field affects significantly the ion Mach number. The variation of the ion Mach number with the incident angle of the ions is also presented.

The Bohm criterion for a collisinal plasma sheath in an oblique magnetic field is investigated with a two-fluid model. It is shown that the upper and lower limits for the sheath criterion exist. And the range of the ion Mach number depends on the magnetic field and the incidence status of the ions.