A method for configuring a plasma processing chamber for preventing a plasma un-confinement event during processing of a substrate from occurring outside of a confined plasma sustaining region is provided. The confined plasma sustaining region is defined by a set of confinement rings surrounding a bottom portion of an electrode is provided. The method includes determining a worst-case Debye length for a plasma generated in the plasma processing chamber during the processing. The method also includes performing at least one of adjusting gaps between any pair of adjacent confinement rings and adding at least one additional confinement ring to ensure that a gap between the any pair of adjacent confinement rings is less than the worst-case Debye length.