  Most plasmas have a very thin sheath compared with the plasma dimension. This
necessitates separate calculations of the plasma and sheath. The Bohm criterion
provides the boundary condition for calculation of plasma profiles. To
calculate sheath properties a value of electric field at the plasma-sheath
interface has to be specified in addition to the Bohm criterion. The value of
the boundary electric field and robust procedure to approximately patch plasma
and collisionless sheath with a very good accuracy are reported.
