The Bohm-sheath criterion in plasmas containing electrons and multiply charged ions

Using the multi-fluid model of plasmas, we have analytically obtained a generalized Bohm criterion in the plasma, including hot electrons and multiply charged ions, and have numerically examined its validity. The new Bohm-sheath criterion shows that increasing the charge number of positive ions and decreasing the charge number of negative ions would increase the minimum ion speed that is required for the Bohm criterion to satisfy.