Abstract: Ring gap nozzle for distributing a fluid medium over a plate, comprising an axial channel passing through the plate, a cap which covers the channel, leaving a ring gap between it and the plate, and a connecting member extending coaxially through the channel for holding the cap in place. A wall which defines a rotationally symmetrical flow space extends from the connecting member to the outlet edge of the totally free ring gap. The annular flow space comprises a region of the channel, of a deflection space and of the ring gap. All the walls which bound it are arranged so that, starting at least in the deflection space, the flooded area of cross section of the annular flow space decreases continuously in the direction of the flow of medium towards the outlet edge of the ring gap.