Cylinder having a partially gas-permeable surface

A cylinder comprising a cylindrical body, characterized in that a first proportion of a circumferential face of the cylindrical body is of porous and gas-permeable configuration and a second proportion of the circumferential face of the cylindrical body is of gas-impermeable configuration, where the porous, gas-permeable first proportion of the circumferential face is in communication with at least one gas supply line and where the first proportion of the circumferential face amounts to at least 0.1% and at most 50%, characterized in that the porous, gas-permeable first proportion of the circumferential face is divided into at least one porous region, wherein the at least one porous region is configured as a ring circulating in the peripheral direction or as a plurality of subregions which are configured and disposed in the form of an interrupted ring circulating in the peripheral direction.