Method and device (10) for suppressing sputtering glow in a gas to be transported across a voltage drop region (X-Y) under conditions where the gas would otherwise tend to support a glow discharge. The device includes an insulating member, such as a plastic tube (70), having a passage for transporting the gas across the voltage drop, the passage being packed with a porous insulating material, such as fiberglass strands (71), arranged so as to suppress glow discharge in the gas. Preferably, the insulating material is arranged so that there is very little pressure drop across the insulating member. In specific embodiments, the suppression device is used in a gas feed line (11) for supplying a sputtering gas, such as argon or a mixture of argon and nitrogen, or argon and oxygen, to a negatively charged cathode cell (12) of a sputtering machine (13), at very low absolute pressure.