Experimental results have shown that a beam power density of 1667 wattssq cm can be dissipated in an electrode which consists of a narrow bore tubing, if the tubing is filled with copper mesh to a 20 density and water at a low rate is passed through the tubing. It is shown that this high power density can be dissipated because the mesh surface area is sufficient to drop the power density at the point of transfer to the coolant to a density less than or equal to 135 wattssq cm. The surface of the mesh is effective due to some combination, yet to be determined, of thermal conductivity of the mesh and vapor transport. An experiment designed to verify the proposed mechanism and determine the contribution of the mesh thermal conductivity is planned for the next phase of the study. The results of this experiment will allow the extrapolation of the results to other electrode geometries.