Abstract: A magnet assembly for a plasma process chamber has a hollow collar comprising a cross-section that is absent seams. The hollow collar has an open end face and a cap is provided to seal the open end face of the collar. A plurality of magnets are in the hollow collar, the magnets being insertable through the open end face. The collar is capable of being snap fitted onto the chamber wall. The magnet assembly can also comprise one or more of the collars such that the collars, when installed, form a substantially continuous ring about a chamber wall.