Refractory rf ovens and sputter probes for electron cyclotron resonance ion source

Abstract

Beams from electron cyclotron resonance ion source (ECRIS) with radio frequency ovens for refractory material (using a Mo coil) were recently demonstrated; results for Ti and V are here discussed, with temperature T(s) > or = 2300 K stably maintained and extracted current of about 1000 nA for V(8+) and V(9+). The status of sputter probes is also reported, and the reason why trapping efficiency may be lower than in the oven case are investigated. The simple tubular probe concept show typical currents of Sn(18+) about 250 nA, for the most abundant isotopes, but an operating pressure of about 300 microPa may be required. Some preliminary experiments were performed with Penning probes, showing that transmission of Sn or Pr from Penning cathode to ECRIS plasma is limited. Placement of tin onto anticathode and use of collimator between Penning and ECRIS are also discussed.