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 sheath criterion for an electronegative plasma composed of hot electrons,hot negative ions and cold positive ions in an oblique magnetic field is investigated.We discuss the effects of negative ions and external magnetic field on the sheath criterion.We find that the ion Mach number is of relatively low value because of Coulomb attraction between positive and negative ions.Also the ion Mach number depends on the magnitude and the angle of the magnetic field as well as the initial velocity of ion flow.
