Voltage drops associated with the collisional sheath of nonemitting, MHD electrodes are investigated. The problem is described by a set of coupled nonlinear partial differential equations which are solved by finite differencing in a computer. The sheath and ambipolar regions form in a selfhyphen;consistent way obviating the need to match boundaries. A twohyphen;dimensional model with periodic active sites on a flat plate is used. The current constricts at these sites in order to satisfy the controlling equations for frozen charge flow. The effects of a magnetic field as well as of Joule heating are included in the model; convection can be shown to be negligible in the sheath. Joule heating is assumed to have no effect on the bulk temperature of the gas. Changes in the currenthyphen;voltage characteristics due to Joule heating are small since the effect is extremely localized; the presence of a magnetic field has a slight influence on the size of the sheath but alters noticeably the currenthyphen;voltage characteristics.
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