Abstract: A gas injection subsystem for use in an inspection system serves to inspect a sample by use of charged particles. At least one gas duct of the gas injection subsystem guides a gas flow from a gas reservoir to a sample inspection region. The gas duct has in the vicinity of the sample inspection region a diameter which is less than 5 mm. At least one flow control valve of the gas injection subsystem controls the gas flow through the gas duct. The valve is switchable between an open valve state in which a nominal gas flow through the gas duct is enabled and a closed valve state in which the gas duct is closed to inhibit a gas flow through the gas duct. The valve is designed such that a switching time between the open and the closed state is 100 ms at most. A gas injection subsystem results which facilitates a reproducible gas injection to the sample inspection region.