Operating principle of the plasma beam ion source

The plasma beam ion source is a high current ion source of the plasmatron family. It was originally designed for the injection of low energy proton beams into RFQ accelerators. The source consists of a duoplasmatron and one or two adjacent chambers, where the plasma from the primary DP‐discharge is guided and compressed by an inhomogeneous solenoidal field. A high density plasma column of 200 mm length and 1–4 mm diameter is formed. In this second stage the plasma can be manipulated with a great degree of independence from the primary discharge, thus allowing, for instance, the adjustment of the electron energy to enhance a certain ionization process (e.g., a proton fraction >90% can be obtained). With argon as an auxiliary gas in the primary discharge the production of oxygen ions in the second stage is possible. By the insertion of a probe into the fringe of the plasma beam and the subsequent evaporation, ions from various solids including carbon, iron, copper, or tungsten have been produced.