On the mechanisms of light and heavy impurity release during RF plasma heating in the Uragan-3 Torsatron

Mechanisms of light (oxygen, carbon) and heavy (metal atoms) impurity production have been studied in the URAGAN-3 torsatron, where the RF method is the only one to produce and heat the plasma. The study of the impurity amount in the edge plasma versus the average density ne and the input RF power has shown that the metal and carbon impurities arise due to physical sputtering of metal and carbon-containing materials. Yet, the mechanism of oxygen release is different, and originates from a chemical hydrogen-metal oxide interaction on the surface.