Abstract: Disclosed is a gas inlet device comprising a gas reservoir (5), which is connected via a supply line (11) via a supply flow restrictor (10) which can be closed by a supply valve 13). The gas can be supplied into the antechamber (5) via a control valve (6) and a control flow restrictor (4). As the control valve (6) and the supply valve (13) close the antechamber from the outside, there are only minimal fluctuations in pressure during switching. By this means the pressure in the antechamber (5) can be controlled precisely and the gas flow from the antechamber (5) into the supply line (11) can be set with great precision.