A dielectric arrestor insert for use in a chamber wafer processing system having a gas input line, an arrestor housing and a wafer processing space. The input line is able to provide gas to the arrestor housing. The arrestor housing is able to house the dielectric arrestor insert. The dielectric arrestor insert comprises a gas entry portion, a non-linear channel and a gas exit portion. The gas entry portion is arranged to receive the gas from the input line. The non-linear channel is arranged to deliver the gas from the gas entry portion to the gas exit portion. The gas exit portion is arranged to deliver the gas from the non-linear channel to the wafer processing space.