Review of plasma-impurity sources during tokamak operation

A general review is given on the present status of understanding plasma impurity sources which occur during non-disruptive tokamak operation. Included in the review are the processes of arcing, physical sputtering, neutron sputtering, desorption, chemical erosion, blistering, and backscattering. Excluded from the study are vaporization sources which are associated with the breakdown and initial startup phases of the plasma burn and major disruptions. The aspects of each impurity source which is discussed cover the theoretical and empirical models, the significance of the impurity yield, and the relevance of the process in consideration of near-term and future tokamak plasma-edge conditions